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Universe and Solar System PYQs – Geography, SSC & Railway

93 Universe and Solar System (Geography) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 93 questionsSSC 77 · Railway 16
SSC Stenographer 2026 – 15 September 2026 Shift 2 · Planets and their features

Q1. Which planet is closest to the Sun?

  1. (a) Venus
  2. (b) Earth
  3. (c) Mercury
  4. (d) Mars
Answer & solution

Answer: (c) Mercury

Answer: Option 3 — Mercury
Mercury is the innermost planet, orbiting the Sun at an average distance of about 58 million km (roughly 0.39 AU).
The order outward is Mercury, Venus, Earth, Mars, then the four giant planets.
Revision note — Mercury and the inner planets
• Mercury is the smallest planet of the solar system and the fastest — one revolution takes only 88 Earth days.
• It rotates slowly, once in about 59 Earth days, and has no moon and almost no atmosphere, so its day side is scorching and its night side freezing.
• It is not the hottest planet — that is Venus (about 465 °C), whose thick carbon dioxide atmosphere traps heat by the greenhouse effect.
• Venus is the brightest planet in our sky, the Morning and Evening Star, and rotates east to west with a day longer than its year.
• Earth is the fifth largest planet and the only one with liquid surface water — the Blue Planet; Mars is the Red Planet, coloured by iron oxide, with two moons, Phobos and Deimos.
• The four inner planets — Mercury, Venus, Earth, Mars — are the rocky terrestrial planets; the outer four are the gaseous Jovian planets.
Do not mix these up
• Closest vs hottest — Mercury is closest to the Sun but Venus is hotter, because Mercury has no atmosphere to hold the heat.
• Smallest planet vs smallest body — Mercury is the smallest planet; Pluto is smaller but has been a dwarf planet since 2006.
Also asked from this topic: why Venus is hotter than Mercury (greenhouse effect of its atmosphere); the planet with the longest day (Venus); Earth's rank by size among the planets (fifth largest).
SSC Stenographer 2026 – 11 September 2026 Shift 1 · Planets and their features

Q2. Which phenomenon explains the apparent retrograde motion of planets as seen from Earth?

  1. (a) Precession
  2. (b) Gravitational lensing
  3. (c) Orbital resonance
  4. (d) Relative planetary motion
Answer & solution

Answer: (d) Relative planetary motion

Answer: Option 4 — Relative planetary motion
No planet actually reverses. The Earth, on a faster inner orbit, overtakes an outer planet, and for a few weeks that planet appears to slide backwards (east to west) against the fixed stars.
It is a line-of-sight effect of relative motion, exactly like a slower car seeming to drift backwards as you pass it.
Revision note — Retrograde motion and the solar system
• Mars, Jupiter and Saturn show apparent retrograde loops around opposition; Mars does so about once every 26 months.
• The heliocentric model of Nicolaus Copernicus (De revolutionibus, 1543) explained retrograde motion naturally; Ptolemy's geocentric model had needed epicycles.
• All eight planets revolve around the Sun in the same direction, west to east, anticlockwise as seen from above the Earth's north pole.
• Venus and Uranus rotate in the opposite sense — a real retrograde rotation, not an apparent one. On Venus the Sun rises in the west.
• Precession is the slow wobble of the Earth's axis, one full cone in about 25,800 years, first noted by Hipparchus.
• Gravitational lensing is the bending of light by mass, predicted by Einstein's General Theory of Relativity (1915) and confirmed by Eddington in 1919.
• Orbital resonance is a periodic tug between bodies whose periods form a simple ratio — Neptune and Pluto at 3:2, and Io, Europa and Ganymede at 1:2:4.
Do not mix these up
• Apparent retrograde motion vs retrograde rotation — the first is an illusion of relative motion; the second is the genuine backward spin of Venus and Uranus.
• Precession vs retrograde motion — precession moves the Earth's axis over millennia; retrograde motion is a planet's apparent path over weeks.
Also asked from this topic: the planet whose rotation axis lies nearly in its orbital plane (Uranus, tilted about 98 degrees); the two small irregular moons of Mars (Phobos and Deimos).
SSC Stenographer 2026 – 11 September 2026 Shift 1 · Moons and dwarf planets

Q3. As of July 2025, what is the Earth’s only natural satellite?

  1. (a) Mars
  2. (b) Moon
  3. (c) Venus
  4. (d) Ganymede
Answer & solution

Answer: (b) Moon

Answer: Option 2 — Moon
A natural satellite is a body that orbits a planet without having been made by people, and the Earth has exactly one — the Moon.
It lies about 3,84,400 km away and circles the Earth once in about 27.3 days.
Revision note — The Moon and the satellites of the solar system
• Mean Earth–Moon distance 3,84,400 km; moonlight reaches us in about 1.3 seconds.
• Sidereal month = 27.3 days (one orbit measured against the stars); synodic month = 29.5 days (new moon to new moon), which is what the lunar calendar counts.
• The Moon rotates in the same time it revolves — synchronous rotation — so the same face always points at us; about 59 per cent of the surface becomes visible over time because of libration.
• Diameter about 3,474 km, roughly a quarter of the Earth's; surface gravity about one-sixth of the Earth's; no atmosphere, hence no sound, no weather and extreme day-night temperatures.
• Other satellites worth knowing: Ganymede is the largest moon in the solar system and belongs to Jupiter; Titan is Saturn's largest; Mars has two — Phobos and Deimos; Mercury and Venus have none.
• Chandrayaan-1 (2008) first confirmed water molecules on the Moon; Chandrayaan-3 soft-landed near the lunar south pole on 23 August 2023, making India the first country to do so.
Do not mix these up
• Natural vs artificial satellite — the Moon orbits the Earth on its own; Aryabhata (1975), INSAT and GSAT were launched by people.
• Planet vs satellite — a planet goes round the Sun (Mars, Venus); a satellite goes round a planet (the Moon, Ganymede).
Also asked from this topic: natural versus artificial satellite (the Moon is natural); the Moon's daily motion (about 13.3 degrees); the mission that first found lunar water (Chandrayaan-1).
SSC Stenographer 2026 – 10 September 2026 Shift 1 · Moons and dwarf planets

Q4. What is the most accepted explanation for the Moon's origin?

  1. (a) Capture theory
  2. (b) Co-formation theory
  3. (c) Giant impact hypothesis
  4. (d) Fission theory
Answer & solution

Answer: (c) Giant impact hypothesis

Answer: Option 3 — Giant impact hypothesis
The accepted explanation is that a Mars-sized body called Theia struck the young Earth about 4.5 billion years ago.
The debris flung into orbit gathered together to form the Moon.
Revision note — The Moon and its origin
• The giant impact hypothesis (also called the Big Splash) explains why lunar rock matches the Earth's mantle in oxygen isotopes, and why the Moon has only a very small iron core.
• The older fission theory (George Darwin) said the Moon was flung out of a fast-spinning Earth.
• The capture theory said a passing body was trapped by Earth's gravity; the co-formation theory said the two condensed side by side from one cloud.
• All three older models fail on the angular momentum and composition evidence, which is why the impact model is preferred.
• The Moon is Earth's only natural satellite, about 3,474 km across and about 3,84,400 km away on average.
• It is in synchronous rotation (tidally locked) — rotation period and orbital period are both about 27.3 days, so the same face always turns towards us.
• Gravity on the Moon is about one-sixth of the Earth's, and moonlight takes about 1.3 seconds to reach us.
• Chandrayaan-1 (2008) confirmed water on the lunar surface; Chandrayaan-3 landed near the south pole on 23 August 2023.
Do not mix these up
• Giant impact vs fission theory — in the impact model the Moon forms from debris of a collision with another body; in the fission model it is thrown off the Earth itself by rapid spin.
• Capture vs co-formation — capture makes the Moon a stranger caught by Earth's gravity; co-formation makes it a twin born from the same cloud at the same time.
Also asked from this topic: why we always see one face of the Moon (its rotation period equals its orbital period); the Moon's orbital period (about 27 days); the mission that found water (Chandrayaan-1).
SSC Stenographer 2026 – 10 September 2026 Shift 2 · Planets and their features

Q5. Which of the following accurately explains the reason Mars loses its atmosphere to space over time?

  1. (a) Excess greenhouse gases causing evaporation
  2. (b) High levels of sulfuric acid clouds
  3. (c) Lack of a global magnetic field to deflect solar wind
  4. (d) Presence of ozone destroying UV shield
Answer & solution

Answer: (c) Lack of a global magnetic field to deflect solar wind

Answer: Option 3 — Lack of a global magnetic field to deflect solar wind
Mars has no global magnetic field today, so the solar wind strikes its upper atmosphere directly and strips the gas away into space.
NASA's MAVEN orbiter was sent in 2013 precisely to measure this escape.
Revision note — Mars and the loss of planetary atmospheres
• Mars's internal dynamo shut down about 4 billion years ago as its small core cooled; only weak crustal magnetism survives in patches.
• The Earth keeps its air because the liquid iron-nickel outer core runs a geodynamo, and the resulting magnetosphere deflects the solar wind.
• Mars's atmosphere is now thin — surface pressure about 6 millibar against 1,013 millibar on Earth — and about 95 per cent carbon dioxide.
• Weak gravity helps the loss: Mars has about 38 per cent of Earth's surface gravity and an escape velocity of only 5.0 km/s, against 11.2 km/s for Earth.
• Venus also lacks a global magnetic field, yet keeps a dense atmosphere because it is far more massive; its clouds are of sulphuric acid (H₂SO₄).
• India's Mars Orbiter Mission (Mangalyaan), launched on 5 November 2013, made India the first country to reach Mars orbit on its maiden attempt.
Do not mix these up
• Magnetic shielding vs the greenhouse effect — a missing magnetic field lets the atmosphere escape; the greenhouse effect only traps heat in whatever air is left.
• Mars vs Venus — sulphuric acid clouds and a runaway greenhouse belong to Venus; Mars is cold and nearly airless.
Also asked from this topic: the layer that generates the Earth's magnetic field (outer core); the acid in the atmosphere of Venus (H₂SO₄); India's first interplanetary mission (Mangalyaan).
SSC Stenographer 2026 – 10 September 2026 Shift 3 · Universe, galaxies and Big Bang

Q6. Which of the following statements about the ΛCDM (Lambda Cold Dark Matter) cosmological model is incorrect?

  1. (a) The ΛCDM model incorporates the cosmological constant (Λ) to explain the observed accelerated expansion of the universe.
  2. (b) It assumes that dark matter is composed of hot, relativistic particles that decouple early in the universe's evolution.
  3. (c) The model successfully explains the large-scale structure formation and the cosmic microwave background (CMB) anisotropies observed by missions like Planck.
  4. (d) Ordinary baryonic matter constitutes only about 5% of the total energy density of the universe according to the ΛCDM model.
Answer & solution

Answer: (b) It assumes that dark matter is composed of hot, relativistic particles that decouple early in the universe's evolution.

Answer: Option 2 — It assumes that dark matter is composed of hot, relativistic particles that decouple early in the universe's evolution
The CDM in ΛCDM stands for cold dark matter — slow-moving, non-relativistic particles.
Hot dark matter is the rival idea the observations rejected, so this is the statement that is incorrect.
Revision note — The ΛCDM (Lambda Cold Dark Matter) model
• ΛCDM is the standard model of cosmology: Λ is the cosmological constant, that is dark energy, and CDM is cold dark matter.
• Its energy budget is roughly 68 to 69 per cent dark energy, 26 to 27 per cent dark matter and only about 5 per cent ordinary baryonic matter, so option 4 is a correct statement.
• Cold means the particles were already non-relativistic when they decoupled, so small clumps formed first and merged upward — bottom-up structure formation.
• Hot dark matter, made of fast light particles such as neutrinos, would have streamed out of small clumps and wiped them out, which the observed galaxy distribution rules out.
• Λ was introduced by Einstein in 1917, dropped, then revived after 1998, when distant supernovae showed the expansion is accelerating (Nobel Prize in Physics, 2011).
• The Planck satellite (ESA, 2009-2013) mapped the CMB anisotropies and fixed the age of the universe at about 13.8 billion years.
Do not mix these up
• Dark matter vs dark energy — dark matter attracts and holds galaxies and clusters together; dark energy acts as a repulsion that accelerates the expansion of space.
• Cold vs hot dark matter — cold is slow and heavy and gives bottom-up structure; hot is relativistic and light, gives top-down, and is ruled out by the data.
Also asked from this topic: the accepted account of the origin of the universe (Big Bang theory); the evidence for it (redshift of galaxies); the project studying dark matter (Square Kilometre Array).
SSC Stenographer 2026 – 10 September 2026 Shift 3 · Universe, galaxies and Big Bang

Q7. What does the discovery of Cosmic Microwave Background Radiation primarily support?

  1. (a) The existence of black holes in all galaxies.
  2. (b) The Big Bang theory of the universe's origin.
  3. (c) The Steady-State theory of constant cosmic density.
  4. (d) That space is completely cold and inert.
Answer & solution

Answer: (b) The Big Bang theory of the universe's origin.

Answer: Option 2 — The Big Bang theory of the universe's origin
The cosmic microwave background is the relic heat of a hot, dense early universe.
That is precisely what the Big Bang predicts, and it is something the rival Steady-State theory cannot produce at all.
Revision note — Cosmic Microwave Background Radiation
• The CMB was discovered accidentally in 1965 by Arno Penzias and Robert Wilson at Bell Laboratories, using a horn antenna at Holmdel; they shared the Nobel Prize in Physics in 1978.
• It had been predicted in the late 1940s by George Gamow, Ralph Alpher and Robert Herman as the leftover radiation of a hot beginning.
• Its temperature today is about 2.725 K, it fills the whole sky almost uniformly, and it peaks in the microwave part of the spectrum.
• It was released when the universe first cooled enough for atoms to form and became transparent to light — about 3,80,000 years after the Big Bang, which NCERT rounds to about 3,00,000 years.
• The tiny ripples in it, the anisotropies, were mapped by COBE (1989), WMAP (2001) and Planck (2009), and are the seeds from which galaxies grew.
• It is the single strongest piece of evidence against the Steady-State theory of Hoyle, Bondi and Gold, which held that the universe has no beginning and a constant density.
Do not mix these up
• CMB vs redshift — the redshift of galaxies (Hubble, 1929) shows the universe is expanding; the CMB shows it was once hot and dense. Both support the Big Bang, by different routes.
• Big Bang vs Steady-State — the Big Bang has a definite beginning about 13.8 billion years ago; Steady-State claims continuous creation of matter and no beginning at all.
Also asked from this topic: the accepted explanation of the origin of the universe (Big Bang theory); the evidence for it (redshift of galaxies); when the universe became transparent (about 3,00,000 years).
SSC Stenographer 2026 – 9 September 2026 Shift 1 · Moons and dwarf planets

Q8. What term is used for a moon that occurs on the second full moon within a calendar month?

  1. (a) Blood moon
  2. (b) Blue moon
  3. (c) Super moon
  4. (d) Harvest moon
Answer & solution

Answer: (b) Blue moon

Answer: Option 2 — Blue moon
A second full moon inside the same calendar month is called a Blue Moon. The name is only a calendar label — the Moon does not actually turn blue.
Revision note — The names given to the Moon
• A Blue Moon is possible because the lunar (synodic) month is about 29.5 days, slightly shorter than most calendar months, so a month can just hold two full moons.
• It recurs roughly once in 2.5 years, which is where the phrase once in a blue moon comes from.
• An older, seasonal definition calls the third full moon in a season that has four full moons a blue moon.
• Blood moon — the coppery-red Moon of a total lunar eclipse. Blue light is scattered out of the sunlight bent through the Earth's atmosphere, so mainly red light reaches the Moon.
• Supermoon — a full moon at perigee, the Moon's nearest point to Earth, so it looks larger and brighter. A micromoon is the opposite, at apogee.
• Harvest moon — the full moon nearest the autumn equinox, around late September.
• A lunar eclipse can occur only on a full moon, a solar eclipse only on a new moon.
Do not mix these up
• Blue moon vs blood moon — the blue moon is a calendar event (a second full moon in one month); the blood moon is an optical one (a total lunar eclipse).
• Blue moon vs supermoon — a blue moon is about when the full moon falls; a supermoon is about how near the Moon is.
Also asked from this topic: the phenomenon caused by the Earth blocking sunlight from reaching the Moon (lunar eclipse);
the phase on which a lunar eclipse can occur (full moon); the phase on which a solar eclipse occurs (new moon).
SSC Stenographer 2026 – 9 September 2026 Shift 2 · Universe, galaxies and Big Bang

Q9. Which of the following statements about quasars is most accurate?

  1. (a) They are dying stars emitting intense gamma rays.
  2. (b) They are neutron stars with strong magnetic fields.
  3. (c) They are active galactic nuclei powered by supermassive black holes.
  4. (d) They are regions of low gravity near wormholes.
Answer & solution

Answer: (c) They are active galactic nuclei powered by supermassive black holes.

Answer: Option 3 — They are active galactic nuclei powered by supermassive black holes.
A quasar, short for quasi-stellar radio source, is the blazing nucleus of a distant galaxy, lit by matter spiralling into a supermassive black hole.
Revision note — Quasars and active galaxies
• Quasars were identified in 1963 by Maarten Schmidt, who measured the large redshift of 3C 273 and showed it was billions of light years away, not a nearby star.
• The power comes from the accretion disc around a black hole of millions to billions of solar masses; a quasar can outshine every star of its host galaxy together.
• Quasars, blazars, Seyfert galaxies and radio galaxies are all active galactic nuclei; what mainly differs is the angle from which we see the disc and its jets.
• Being so far off, quasars are seen as they were in the early universe, which makes them useful cosmological beacons.
• A pulsar, by contrast, is a rapidly rotating, highly magnetised neutron star sending out regular radio pulses — found by Jocelyn Bell Burnell in 1967.
• Above the Chandrasekhar limit of about 1.4 solar masses a white dwarf cannot survive; the star ends as a neutron star or a black hole.
Do not mix these up
• Quasar vs pulsar — a quasar is a galactic nucleus with a supermassive black hole; a pulsar is a single spinning neutron star.
• Black hole vs event horizon — the event horizon is only the boundary beyond which light cannot escape, so the X-rays we detect come from the hot accretion disc outside it.
Also asked from this topic: the telescope that first imaged a black hole (Event Horizon Telescope, 2019); the Chandrasekhar limit (about 1.4 solar masses); what pulsars are (rapidly rotating neutron stars).
SSC Stenographer 2026 – 9 September 2026 Shift 2 · Eclipses, seasons, day and night

Q10. During which event does the Moon come between the Earth and the Sun, casting a shadow on Earth?

  1. (a) Lunar Eclipse
  2. (b) Solar Eclipse
  3. (c) Equinox
  4. (d) Meteor Shower
Answer & solution

Answer: (b) Solar Eclipse

Answer: Option 2 — Solar Eclipse
A solar eclipse happens at new moon, when the Moon passes between the Sun and the Earth and its shadow falls on the Earth's surface.
Revision note — Eclipses
• Solar eclipse: the order is Sun — Moon — Earth; it can occur only on a new moon day, and the Moon's shadow falls on the Earth.
• Lunar eclipse: the order is Sun — Earth — Moon; it can occur only on a full moon day, and the Earth's shadow falls on the Moon.
• The Moon's shadow has a dark inner cone, the umbra, which gives a total eclipse, and a lighter outer cone, the penumbra, which gives a partial one.
• An annular solar eclipse leaves a bright ring of fire because the Moon is near apogee and looks too small to cover the Sun's disc.
• An eclipse does not happen every month because the Moon's orbit is tilted about 5 degrees to the plane of the Earth's orbit; eclipses occur only when the Moon is near a node.
• A solar eclipse is seen only along a narrow track and lasts a few minutes; a lunar eclipse is seen from the whole night side of the Earth and lasts for hours.
Do not mix these up
• Solar vs lunar eclipse — in a solar eclipse the Moon is in the middle and it is a new moon; in a lunar eclipse the Earth is in the middle and it is a full moon.
• Umbra vs penumbra — the umbra produces the total phase, the penumbra only a partial dimming.
Also asked from this topic: the eclipse in which the Moon casts its shadow on the Earth (solar eclipse, at new moon, SSC Stenographer 2025); the alignment of Sun, Earth and Moon in which one casts a shadow on another (an eclipse, SSC Selection Post 2025).
SSC Stenographer 2026 – 9 September 2026 Shift 2 · Eclipses, seasons, day and night

Q11. What astronomical event marks the longest day in the Northern Hemisphere?

  1. (a) Autumnal Equinox
  2. (b) Winter Solstice
  3. (c) Vernal Equinox
  4. (d) Summer Solstice
Answer & solution

Answer: (d) Summer Solstice

Answer: Option 4 — Summer Solstice
On the summer solstice, about 21 June, the Sun's rays fall vertically on the Tropic of Cancer, so the Northern Hemisphere gets its longest day and shortest night.
Revision note — Solstices and equinoxes
• Summer solstice, 21 June: the Sun is overhead at the Tropic of Cancer (23½° N) — longest day in the Northern Hemisphere, shortest in the Southern.
• Winter solstice, 22 December: the Sun is overhead at the Tropic of Capricorn (23½° S) — shortest day in the Northern Hemisphere.
• Vernal equinox, 21 March and autumnal equinox, 23 September: the Sun is overhead at the Equator and day and night are equal everywhere.
• At the June solstice every place at and north of the Arctic Circle (66½° N) has 24 hours of daylight — the midnight Sun.
• Seasons occur because the Earth's axis is tilted 23½° from the perpendicular to its orbital plane and keeps pointing the same way through the year.
• The Earth is actually farthest from the Sun (aphelion, about 4 July) during the northern summer, so distance is not the cause of the seasons.
Do not mix these up
• Solstice vs equinox — a solstice is the extreme position of the overhead Sun, giving the longest or shortest day; an equinox is its crossing of the Equator, when day and night are equal.
• Summer solstice vs aphelion — the solstice depends on the tilt, the aphelion on distance; the two are unrelated.
Also asked from this topic: the longest day in the Northern Hemisphere (summer solstice, 21 June, SSC GD 2026); the overhead-Sun latitude at that solstice (Tropic of Cancer, RRB NTPC 2026); the latitude with the longest June daylight (66½° N, RRB NTPC 2026).
RRB Group D 2025-26 – 19 August 2026 Shift 2 · Eclipses, seasons, day and night

Q12. A climate modeler wants to explain why polar regions have long periods of darkness and light during the year. Which factor is most responsible for this phenomenon?

  1. (a) Atmospheric composition blocks sunlight at the poles
  2. (b) Earth’s axial tilt and spherical shape affect sunlight distribution
  3. (c) Ocean currents change the amount of sunlight received
  4. (d) Only latitude determines day length at the poles
Answer & solution

Answer: (b) Earth’s axial tilt and spherical shape affect sunlight distribution

Correct Answer:
Correct Answer: Option 2 – Earth's axial tilt and spherical shape affect sunlight distribution
Explanation:
The Earth is tilted at about 23.5° on its axis and revolves around the Sun. This combination, together with its spherical shape, causes polar regions to receive continuous sunlight (polar day) for part of the year and no sunlight (polar night) during another part, as the poles alternately tilt toward or away from the Sun.
Important Facts:
• This is why the Arctic and Antarctic experience 'midnight sun' and long polar nights.
• Without axial tilt, day length would not vary seasonally at any latitude.
RRB Group D 2025-26 – 6 August 2026 Shift 1 · Planets and their features

Q13. Venus is hotter than Mercury, even though Mercury is closer to the Sun. Based on Earth’s atmospheric science, which is the most plausible explanation?

  1. (a) Venus receives more sunlight due to its size
  2. (b) Mercury lacks any significant atmospheric layers
  3. (c) Venus's atmosphere creates a strong greenhouse effect
  4. (d) Mercury’s proximity to the Sun creates rapid heat loss
Answer & solution

Answer: (c) Venus's atmosphere creates a strong greenhouse effect

Answer: Option 3 — Venus's atmosphere creates a strong greenhouse effect
Venus's thick CO₂ atmosphere causes an intensegreenhouse effect, making it hotter than Mercury → Option 3.
RRB NTPC UG CBT-1 2025-26 – 13 June 2026 Shift 3 · Eclipses, seasons, day and night

Q14. Which latitude experiences the longest daylight during the June solstice?

  1. (a) Equator
  2. (b) 23½° S
  3. (c) 23½° N
  4. (d) 66½° N
Answer & solution

Answer: (d) 66½° N

June Solstice (Summer Solstice in Northern Hemisphere)
Sun is directly overhead at23½° N (Tropic of Cancer)
Northern Hemisphere receives maximum sunlight
Daylight duration increases from Equator towards North Pole
At66½° N (Arctic Circle): 24 hours daylight
At 23½° N: ~13-14 hours daylight
At Equator: ~12 hours daylight
At 23½° S: ~10-11 hours daylight
Answer: Option 4 → 66½° N
SSC GD 2026 – 26 May 2026 Shift 1 · Eclipses, seasons, day and night

Q15. When is the longest day in the Northern Hemisphere?

  1. (a) Spring Equinox
  2. (b) Autumnal Equinox
  3. (c) Winter Solstice (South Solstice)
  4. (d) Summer Solstice (North Solstice)
Answer & solution

Answer: (d) Summer Solstice (North Solstice)

Correct Answer: Summer Solstice (North Solstice) — Option (d)
The longest day in the Northern Hemisphere occurs on the Summer Solstice ( उत्तर अयनांत ), which falls around June 21 each year. About the Summer Solstice: Summer Solstice (June Solstice): Occurs around June 20-21 each year; The Sun reaches its northernmost position — directly overhead the Tropic of Cancer (23.5°N); The Northern Hemisphere is tilted maximally TOWARD the Sun; This gives the maximum number of daylight hours in the Northern Hemisphere — the LONGEST DAY; The Arctic Circle experiences 24 hours of daylight (Midnight Sun); The Antarctic Circle experiences 24 hours of darkness; About the four key astronomical events: Spring Equinox (March 20-21): Day and night are equal (approximately 12 hours each) in both hemispheres; Sun is directly overhead the Equator; Autumnal Equinox (September 22-23): Again, day and night are approximately equal; Sun again directly over the Equator; Winter Solstice/South Solstice (December 21-22): The Sun is at its southernmost position (overhead Tropic of Capricorn); Northern Hemisphere has the SHORTEST day; Southern Hemisphere has the LONGEST day; Summer Solstice/North Solstice (June 20-21): The Sun is at its northernmost position (overhead Tropic of Cancer); Northern Hemisphere has the LONGEST day ← CORRECT ANSWER; Southern Hemisphere has the shortest day.
Option (a) Spring Equinox — Incorrect: At the Spring Equinox (around March 21), day and night are approximately equal (12 hours each) in both hemispheres — this is NOT the longest day; the longest day in the Northern Hemisphere is the Summer Solstice (June 21). The candidate selected this incorrect option.
Option (b) Autumnal Equinox — Incorrect: At the Autumnal Equinox (around September 23), day and night are again approximately equal — this is NOT the longest day in the Northern Hemisphere; the longest day is the Summer Solstice.
Option (c) Winter Solstice (South Solstice) — Incorrect: The Winter Solstice (around December 22) gives the SHORTEST day in the Northern Hemisphere (and the longest night) — it is the OPPOSITE of the longest day; the longest day in the Northern Hemisphere is the Summer Solstice (June 21).
SSC GD 2026 – 26 May 2026 Shift 2 · Eclipses, seasons, day and night

Q16. When Earth blocks sunlight from reaching the Moon, a lunar eclipse occurs. If Earth were twice its current size, what change would occur in the lunar eclipse?

  1. (a) The eclipse will last longer
  2. (b) The eclipse will become shorter
  3. (c) There will be no change in the eclipse duration
  4. (d) The frequency of eclipses will decrease
Answer & solution

Answer: (a) The eclipse will last longer

Correct Answer: The eclipse will last longer — Option (a)
If Earth were twice its current size, the lunar eclipse would last longer. About Lunar Eclipse and Earth's Size: A lunar eclipse occurs when Earth comes between the Sun and the Moon, blocking sunlight from reaching the Moon; Earth's shadow has two parts: Umbra (complete shadow) — the region where Earth completely blocks sunlight; Penumbra (partial shadow) — the region where Earth partially blocks sunlight; During a total lunar eclipse, the Moon passes through Earth's umbra; The duration of the eclipse depends on: The size of Earth's shadow (umbra) — larger Earth = larger shadow; The distance of the Moon from Earth; The speed of the Moon's orbital motion; Effect of doubling Earth's size: If Earth were twice its current size, its shadow (umbra) would be significantly larger; A larger shadow means the Moon would take MORE TIME to pass through Earth's shadow; Therefore, the lunar eclipse would last LONGER; This is a direct consequence of geometry — larger blocking object = larger shadow = longer time for the Moon to traverse the shadow; Key insight: The duration of the eclipse is proportional to the size of Earth's shadow — NOT to the frequency of eclipses (which depends on orbital alignment); Therefore, doubling Earth's size would increase the duration of each lunar eclipse without necessarily changing the frequency of eclipses.
Option (b) The eclipse will become shorter — Incorrect: If Earth were twice its current size, its shadow would be larger (not smaller), which means the Moon would take LONGER to pass through Earth's shadow — the eclipse would last LONGER, not shorter.
Option (c) There will be no change in the eclipse duration — Incorrect: The size of Earth directly determines the size of its shadow; a larger Earth casts a larger umbra; therefore, a Moon-sized object would take longer to cross this larger shadow — the eclipse duration would definitely change (increase). The candidate selected this incorrect option.
Option (d) The frequency of eclipses will decrease — Incorrect: The frequency (how often) lunar eclipses occur depends on the orbital alignment of Sun, Earth, and Moon — it is governed by the Moon's orbital period and the tilt of its orbit relative to Earth's orbit; doubling Earth's size would not significantly affect orbital mechanics or frequency of eclipses; the primary effect would be on the DURATION of each eclipse (it would last longer).
SSC GD 2026 – 26 May 2026 Shift 3 · Moons and dwarf planets

Q17. Why do we always see the same face/side of the Moon from Earth?

  1. (a) The Moon does not rotate on its own axis
  2. (b) The Moon takes the same time to orbit Earth as it takes to complete one rotation on its axis
  3. (c) Earth's rotation cancels out the Moon's rotation
  4. (d) The Moon is tidally locked with the Sun
Answer & solution

Answer: (b) The Moon takes the same time to orbit Earth as it takes to complete one rotation on its axis

Correct Answer: The Moon takes the same time to orbit Earth as it takes to complete one rotation on its axis — Option (b)
We always see the same side of the Moon because the Moon's rotational period equals its orbital period — this is called synchronous rotation or tidal locking. About Synchronous Rotation (Tidal Locking): Orbital period of Moon around Earth: approximately 27.3 days (sidereal month); Rotational period of Moon on its axis: approximately 27.3 days; Since both periods are EQUAL, the same face of the Moon always faces Earth; This phenomenon is called 'Synchronous Rotation' or 'Tidal Locking'; How tidal locking occurred: Earth's gravitational pull created tidal forces on the Moon; These tidal forces gradually slowed the Moon's rotation over billions of years; Eventually, the Moon's rotation synchronized with its orbital period — this is now the stable configuration; The near side vs the far side: Near side (facing Earth): Always visible from Earth; explored by many landers including Apollo missions; Far side (facing away): Never visible from Earth; first photographed by Soviet Luna 3 (1959); first landing by China's Chang'e-4 (2019); Key facts: The Moon does not completely hide its far side — it wobbles slightly ( libration ), so about 59% of the Moon's surface is visible over time; Libration is caused by: the elliptical shape of Moon's orbit, tilt of Moon's axis, and Earth's position in Moon's orbit.
Option (a) The Moon does not rotate on its own axis — Incorrect: This is a common misconception; the Moon DOES rotate on its own axis — it completes one full rotation approximately every 27.3 days; the reason we see the same face is that this rotation period equals its orbital period (synchronous rotation), NOT that it doesn't rotate.
Option (c) Earth's rotation cancels out the Moon's rotation — Incorrect: Earth's rotation does NOT cancel the Moon's rotation; they are independent; the reason we always see the same face of the Moon is synchronous rotation — the Moon's rotational period equals its orbital period due to tidal locking by Earth's gravity.
Option (d) The Moon is tidally locked with the Sun — Incorrect: The Moon is NOT tidally locked with the Sun — it is tidally locked with EARTH; the Sun's tidal effect on the Moon is much weaker than Earth's; the synchronous rotation of the Moon is due to Earth's gravitational tidal forces, not the Sun's.
SSC GD 2026 – 25 May 2026 Shift 1 · Planets and their features

Q18. Which of the following planets is the fifth largest planet in our solar system by size?

  1. (a) Mercury
  2. (b) Venus
  3. (c) Earth
  4. (d) Uranus
Answer & solution

Answer: (c) Earth

Correct Answer: Earth — Option (c)
Earth is the fifth largest planet in our solar system by size. Planets of the Solar System ranked by size (largest to smallest): 1st — Jupiter (largest): Diameter ~142,984 km; 2nd — Saturn: Diameter ~120,536 km; 3rd — Uranus: Diameter ~51,118 km; 4th — Neptune: Diameter ~49,528 km; 5th — Earth: Diameter ~12,742 km; 6th — Venus: Diameter ~12,104 km; 7th — Mars: Diameter ~6,779 km; 8th — Mercury (smallest): Diameter ~4,879 km; Key fact: Among the terrestrial planets (Mercury, Venus, Earth, Mars), Earth is the LARGEST; Among all 8 planets, Earth ranks 5th in size; Earth vs Venus: Earth and Venus are similar in size ('sister planets') — Earth is slightly larger than Venus; Mnemonic to remember planet sizes: 'My Very Educated Mother Just Served Us Nachos' (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) — but remember this is orbital order, not size order; About Earth: Average radius: 6,371 km; Mass: 5.972 × 10²⁴ kg; Only known planet with life; Atmosphere: Nitrogen (78%), Oxygen (21%), Argon (0.9%); Has one natural satellite — the Moon.
Option (a) Mercury — Incorrect: Mercury is the SMALLEST planet in the solar system (8th by size), not the 5th largest; Earth is the 5th largest planet.
Option (b) Venus — Incorrect: Venus is the 6th largest planet in the solar system — slightly smaller than Earth; Earth is the 5th largest. The candidate selected this incorrect option.
Option (d) Uranus — Incorrect: Uranus is the 3rd largest planet in the solar system (diameter ~51,118 km) — much larger than Earth; Earth is the 5th largest.
SSC GD 2026 – 25 May 2026 Shift 3 · Planets and their features

Q19. Which of the following planets is NOT made of gases and liquids?

  1. (a) Saturn
  2. (b) Uranus
  3. (c) Jupiter
  4. (d) Venus
Answer & solution

Answer: (d) Venus

Correct Answer: Venus — Option (d)
Venus is NOT made of gases and liquids — it is a terrestrial (rocky) planet. Classification of planets in the Solar System: Terrestrial (Rocky) planets — made of rock, metal, and silicates: Mercury, Venus, Earth, Mars; These planets have solid surfaces; Gas Giants — primarily made of hydrogen and helium gases: Jupiter, Saturn; These planets have no definite solid surface — they have gaseous outer layers and liquid/metallic hydrogen interiors; Ice Giants — primarily made of water ice, ammonia ice, and methane ice along with gases: Uranus, Neptune; These have a thick mantle of ices over a rocky core; About Venus: Venus is a terrestrial planet (like Earth); Composition: Rocky/silicate mantle and a metallic (iron-nickel) core; Has a solid surface (though extremely hot ~465°C due to extreme greenhouse effect); Venus has a dense CO2 atmosphere (96.5% CO2), but the planet ITSELF is made of rock and metal — not gases and liquids; It is sometimes called Earth's 'twin' due to similar size and composition; About Saturn, Uranus, Jupiter (the incorrect options): Saturn: Gas giant — primarily hydrogen and helium; famous for its ring system; Uranus: Ice giant — made of water, ammonia, methane ices and gases; also has a ring system; Jupiter: Gas giant — largest planet; primarily hydrogen and helium; both are made of gases and liquids (no solid surface).
Option (a) Saturn — Incorrect: Saturn IS a gas giant made of gases (primarily hydrogen and helium) and liquids; it has no solid surface and is specifically categorized as a planet made of gases and liquids; Saturn is NOT the answer to 'NOT made of gases and liquids.'
Option (b) Uranus — Incorrect: Uranus IS an ice giant made of water, ammonia, methane ices and gases — it IS composed of gases and icy liquids; it has no solid surface to stand on; Uranus is not the correct answer.
Option (c) Jupiter — Incorrect: Jupiter IS a gas giant — the largest planet, made primarily of hydrogen and helium in gaseous and liquid states; it has no solid surface; Jupiter is definitely made of gases and liquids.
SSC GD 2026 – 9 May 2026 Shift 3 · Space measurements (light year, astronomical unit)

Q20. A light year is a measure of _____.

  1. (a) Time
  2. (b) Distance
  3. (c) Speed
  4. (d) Mass
Answer & solution

Answer: (b) Distance

Correct Answer: Distance — Option (b)
A light year is a unit of Distance — it is defined as the distance that light travels in one year in a vacuum. Since light travels at approximately 3 × 10⁸ metres per second, one light year equals approximately 9.461 × 10¹⁵ metres (about 9.46 trillion kilometres or 5.88 trillion miles). Light years are used to measure vast astronomical distances between stars and galaxies. For example, the nearest star system to Earth (Proxima Centauri) is about 4.24 light years away. Despite containing the word 'year' (a unit of time), a light year is emphatically a unit of distance.
Option (a) Time — Incorrect: Although the word 'year' appears in 'light year', it is NOT a unit of time; it is a unit of distance (the distance light travels in one year).
Option (c) Speed — Incorrect: The speed of light is measured in metres per second (or km/s); a light year is the distance covered at the speed of light in one year.
Option (d) Mass — Incorrect: Mass is measured in kilograms; a light year measures astronomical distances, not mass.
SSC GD 2026 – 8 May 2026 Shift 2 · Earth - shape, size and motions

Q21. What does 'Geoid' mean?

  1. (a) It means a large shape like the Sun
  2. (b) It means a planet without a moon
  3. (c) It means Earth-like shape
  4. (d) It means a black hole of large size
Answer & solution

Answer: (c) It means Earth-like shape

Correct Answer: It means Earth-like shape — Option (c)
The term 'Geoid' comes from the Greek word 'geo' meaning Earth and 'eidos' meaning shape/form — literally meaning 'Earth-shaped.' In geodesy, the geoid is the hypothetical shape of the Earth defined by mean sea level and its extension under land surfaces. It represents the true physical shape of the Earth based on gravitational and rotational forces, which is an oblate spheroid (slightly flattened at the poles and bulging at the equator).
Option (a) It means a large shape like the Sun — Incorrect: The Sun is a star and has no relation to the meaning of 'geoid'; geoid specifically means Earth-like shape.
Option (b) It means a planet without a moon — Incorrect: 'Geoid' has nothing to do with the presence or absence of a moon; it refers to Earth's shape.
Option (d) It means a black hole of large size — Incorrect: Black holes are collapsed stars; they have no relation to the concept of geoid.
SSC GD 2026 – 8 May 2026 Shift 2 · Moons and dwarf planets

Q22. _____ is the point on the orbit where the vertical distance of the satellite from Earth's surface is minimum.

  1. (a) Apogee
  2. (b) Perigee
  3. (c) Inclination
  4. (d) Lagrange Point
Answer & solution

Answer: (b) Perigee

Correct Answer: Perigee — Option (b)
Perigee is the point in the orbit of a satellite (or any object orbiting Earth) where it is closest to Earth — i.e., where the vertical distance from Earth's surface is minimum. Conversely, the point farthest from Earth is called the Apogee. For orbits around other celestial bodies, similar terms are used: Perihelion (closest to the Sun), Perilune (closest to the Moon), etc.
Option (a) Apogee — Incorrect: Apogee is the point where the satellite is farthest from Earth (maximum distance), opposite to Perigee.
Option (c) Inclination — Incorrect: Inclination refers to the angle between the orbital plane of a satellite and Earth's equatorial plane; it is not a specific orbital point.
Option (d) Lagrange Point — Incorrect: Lagrange Points are specific positions in space where the gravitational forces of two large bodies and the centrifugal force balance each other; they are not the closest orbital point to Earth.
SSC GD 2026 – 7 May 2026 Shift 1 · Space measurements (light year, astronomical unit)

Q23. How can the term 'light year' best be defined?

  1. (a) Time taken by light to travel one hour
  2. (b) Distance travelled by light in one year
  3. (c) Speed of light × time
  4. (d) Time taken by Earth to complete one revolution
Answer & solution

Answer: (b) Distance travelled by light in one year

Correct Answer: Distance travelled by light in one year — Option (b)
A light year is a unit of distance (not time), defined as the distance that light travels in one year in a vacuum. Since the speed of light is approximately 3 × 10⁸ m/s (300,000 km/s), one light year equals approximately 9.461 × 10¹⁵ metres (about 9.46 trillion km). Light years are used to express astronomical distances — for example, the nearest star (Proxima Centauri) is about 4.24 light years away. The term contains 'year' but it is a measure of distance, not time.
Option (a) Time taken by light to travel one hour — Incorrect: A light year is not a unit of time and is not defined in terms of one hour; it is the distance covered in one full year.
Option (c) Speed of light × time — Incorrect: While distance = speed × time, 'light year' specifically means the distance light covers in one year (not an arbitrary time), making this definition incomplete.
Option (d) Time taken by Earth to complete one revolution — Incorrect: Earth's orbital period (one year) is used to define the time frame, but a light year is the DISTANCE light travels in that time, not the time itself.
SSC GD 2026 – 7 May 2026 Shift 3 · Planets and their features

Q24. Which planet is called the 'stormy planet'?

  1. (a) Mercury
  2. (b) Jupiter
  3. (c) Mars
  4. (d) Venus
Answer & solution

Answer: (b) Jupiter

Correct Answer: Jupiter — Option (b)
Jupiter is called the 'stormy planet' due to its extreme and persistent atmospheric storms. The most famous is the Great Red Spot — a massive anticyclonic storm larger than Earth that has been raging for over 350 years. Jupiter's atmosphere features powerful wind jets, enormous storm systems, and lightning activity far exceeding Earth's. The planet has no solid surface, consisting of swirling gas layers (primarily hydrogen and helium) with constant turbulent weather patterns. Jupiter is also the largest planet in our solar system.
Option (a) Mercury — Incorrect: Mercury has virtually no atmosphere and therefore no storms; it is known for extreme temperature fluctuations.
Option (c) Mars — Incorrect: While Mars experiences dust storms (some global in scale), it is not called the 'stormy planet'; Jupiter earns this title due to the Great Red Spot and constant giant storms.
Option (d) Venus — Incorrect: Venus has thick sulfuric acid clouds and strong winds, but it is known as the 'hottest planet' or 'Earth's twin', not the 'stormy planet'.
SSC GD 2026 – 5 May 2026 Shift 2 · Moons and dwarf planets

Q25. If the Moon takes 27 days to complete one orbit around Earth,
how many degrees does it move in its orbit per day?

  1. (a) 13.3°
  2. (b) 27°
  3. (c) 360°
  4. (d) 7°
Answer & solution

Answer: (a) 13.3°

Correct Answer: 13.3° — Option (a)
The Moon completes one full orbit of 360° around Earth in approximately 27 days (sidereal month). To find the daily orbital movement: 360° ÷ 27 days = 13.33° per day. This means the Moon moves approximately 13.3° along its orbit each day. This is also why the Moon rises about 50 minutes later each day — it has moved 13.3° further along its orbit relative to the Sun.
Option (b) 27° — Incorrect: 27° would be the daily movement if the Moon completed its orbit in about 13 days, which is incorrect.
Option (c) 360° — Incorrect: 360° is the total angle of one complete orbit, not the daily movement.
Option (d) 7° — Incorrect: 7° would correspond to an orbital period of about 51 days (360÷7 ≈ 51), which does not match the Moon's actual period.
SSC GD 2026 – 4 May 2026 Shift 1 · Planets and their features

Q26. Why are the days on Venus longer than its years?

  1. (a) Venus has a slower rotation than revolution
  2. (b) Venus revolves very slowly around the Sun
  3. (c) Venus does not rotate
  4. (d) Venus spins on its axis in the opposite direction
Answer & solution

Answer: (a) Venus has a slower rotation than revolution

Correct Answer: Venus has a slower rotation than revolution — Option (a)
A 'day' on Venus (its sidereal rotation period) lasts about 243 Earth days, while a 'year' on Venus (its revolution around the Sun) takes about 225 Earth days. Since Venus rotates extremely slowly on its own axis — slower than its orbital revolution — a Venusian day is longer than a Venusian year.
Option (b) Venus revolves very slowly around the Sun — Incorrect: Venus actually completes its orbit in 225 Earth days, which is shorter than its rotation period.
Option (c) Venus does not rotate — Incorrect: Venus does rotate, just very slowly.
Option (d) Venus spins on its axis in the opposite direction — Incorrect: While Venus does have retrograde rotation (spinning opposite to most planets), this explains why the Sun rises in the west on Venus, not why its day is longer than its year.
SSC GD 2026 – 4 May 2026 Shift 1 · Planets and their features

Q27. Which planet has a magnetic field that is offset from its center and tilted about 59 degrees to its rotational axis?

  1. (a) Earth
  2. (b) Jupiter
  3. (c) Uranus
  4. (d) Saturn
Answer & solution

Answer: (c) Uranus

Correct Answer: Uranus — Option (c)
Uranus has an unusual magnetic field that is significantly offset from its geometric center (by about one-third of the planet's radius) and is tilted at approximately 59 degrees relative to its rotational axis. This makes Uranus's magnetosphere highly asymmetric and unique in our solar system. Scientists believe this anomaly may be related to Uranus's extreme axial tilt of 97.77 degrees.
Option (a) Earth — Incorrect: Earth's magnetic field is tilted about 11 degrees from its rotational axis and is not significantly offset from its center.
Option (b) Jupiter — Incorrect: Jupiter has a strong magnetic field but it is roughly aligned with its rotational axis with a tilt of about 10 degrees.
Option (d) Saturn — Incorrect: Saturn's magnetic field is nearly perfectly aligned with its rotational axis (less than 1 degree tilt), making it unique among gas giants.
SSC GD 2026 – 4 May 2026 Shift 3 · Eclipses, seasons, day and night

Q28. Which astronomical phenomenon occurs as a result of Earth blocking sunlight from reaching the Moon?

  1. (a) Solar eclipse
  2. (b) Lunar eclipse
  3. (c) Meteor shower
  4. (d) Aurora Borealis
Answer & solution

Answer: (b) Lunar eclipse

Correct Answer: Lunar eclipse — Option (b)
A lunar eclipse occurs when the Earth comes between the Sun and the Moon, causing Earth's shadow to fall on the Moon. This blocks sunlight from directly reaching and illuminating the Moon. A lunar eclipse can only occur on a full moon night. The Moon may appear reddish during a total lunar eclipse (called a 'Blood Moon') due to Earth's atmosphere bending some red light onto the Moon.
Option (a) Solar eclipse — Incorrect: A solar eclipse occurs when the Moon comes between the Sun and the Earth, blocking sunlight from reaching Earth — not the other way around.
Option (c) Meteor shower — Incorrect: A meteor shower occurs when Earth passes through debris trails left by comets; it is unrelated to Earth's shadow on the Moon.
Option (d) Aurora Borealis — Incorrect: Aurora Borealis (Northern Lights) is caused by charged particles from the Sun interacting with Earth's magnetic field, not by Earth blocking sunlight.
SSC GD 2026 – 30 April 2026 Shift 2 · Earth - shape, size and motions

Q29. What causes the equatorial precession of the Earth's axis?

  1. (a) Gravitational pull of the Sun and Moon
  2. (b) Earth's rotational speed
  3. (c) Variation in Earth's orbit
  4. (d) Solar wind
Answer & solution

Answer: (a) Gravitational pull of the Sun and Moon

Correct Answer: Gravitational pull of the Sun and Moon — Option (a)
The precession of Earth's axis (axial precession) is caused by the combined gravitational forces of the Sun and the Moon acting on Earth's equatorial bulge. This causes Earth's axis to trace a slow wobble (like a spinning top) over a cycle of approximately 26,000 years, gradually shifting the positions of celestial poles.
Option (b) Earth's rotational speed — Incorrect: Earth's rotation creates the equatorial bulge, but the speed itself does not cause axial precession.
Option (c) Variation in Earth's orbit — Incorrect: Orbital variations relate to Milankovitch cycles affecting climate, not to axial precession.
Option (d) Solar wind — Incorrect: Solar wind affects Earth's magnetosphere and upper atmosphere, not the gravitational precession of its axis.
SSC GD 2026 – 29 April 2026 Shift 1 · Stars and their life cycle

Q30. Orion is a _____.

  1. (a) Constellation
  2. (b) Star
  3. (c) Planet
  4. (d) Satellite
Answer & solution

Answer: (a) Constellation

Correct Answer: Constellation — Option (a)
Orion is one of the most prominent and recognizable constellations ( तारामंडल ) in the night sky. Key facts about Orion: It is named after Orion, a hunter in Greek mythology; It is located on the celestial equator and is visible from most parts of the world; Orion is best visible in the night sky during January-February in the Northern Hemisphere; Notable stars in Orion: Betelgeuse (a red supergiant, marking Orion's right shoulder), Rigel (a blue supergiant, marking Orion's left foot), Bellatrix (Orion's left shoulder), Saiph (Orion's right foot); Orion's Belt: Three prominent stars in a straight line — Alnitak, Alnilam, and Mintaka — form the distinctive 'belt' that makes Orion easily identifiable; The Orion Nebula (M42) is a famous stellar nursery located below Orion's Belt; The International Astronomical Union (IAU) officially recognizes 88 constellations, and Orion is among the most well-known.
Option (b) Star — Incorrect: Orion is not a single star but a constellation — a group of stars that form a recognizable pattern; individual stars within Orion include Betelgeuse and Rigel.
Option (c) Planet — Incorrect: Orion is not a planet; it is a constellation (a group of stars seen as a pattern in the night sky); planets in our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Option (d) Satellite — Incorrect: A satellite is a natural or artificial body orbiting a planet (like the Moon orbiting Earth); Orion is a constellation — a recognizable pattern of stars in the night sky — not a satellite.
SSC GD 2026 – 29 April 2026 Shift 3 · Planets and their features

Q31. Uranus's axial tilt is approximately 98°, meaning it rotates almost on its side. What effect does this have on Uranus's seasons?

  1. (a) Extreme seasonal changes
  2. (b) No seasonal changes
  3. (c) Mild seasons
  4. (d) Permanent day on one side
Answer & solution

Answer: (a) Extreme seasonal changes

Correct Answer: Extreme seasonal changes — Option (a)
Uranus's extreme axial tilt of approximately 98° causes extreme seasonal changes. Scientific explanation: Because of its 98° axial tilt, Uranus essentially rotates on its side; During Uranus's orbit around the Sun (which takes about 84 Earth years), each pole alternately faces the Sun for approximately 42 years: For 42 years, one pole is in continuous sunlight (perpetual summer/day) while the other is in complete darkness (perpetual winter/night); Then for the next 42 years, the poles reverse; The equatorial regions of Uranus receive relatively consistent (but less) sunlight, while the poles experience extreme temperature differences — this creates dramatically extreme seasons; Surface temperature: Despite receiving sunlight for 42 years, the poles do not warm significantly due to Uranus's faint solar heating (being far from the Sun); but the distribution of solar energy varies dramatically. The 98° tilt is believed to have resulted from a massive collision with a planet-sized object early in the solar system's history.
Option (b) No seasonal changes — Incorrect: Uranus's extreme axial tilt of 98° creates the most dramatic seasonal variations of any planet in our solar system; 'no seasonal changes' is the opposite of what actually happens — the extreme tilt creates extreme seasonal changes.
Option (c) Mild seasons — Incorrect: Mild seasons are characteristic of planets with relatively small axial tilts (like Earth's 23.5°, which creates our moderate seasons); Uranus's 98° tilt is the most extreme of any planet, creating extreme (not mild) seasons.
Option (d) Permanent day on one side — Incorrect: 'Permanent day on one side' describes a tidally locked body (like our Moon relative to Earth); Uranus is not tidally locked to the Sun — it rotates (albeit on its side), and its poles experience long periods of sunlight/darkness that alternate over its 84-year orbit. The candidate selected this incorrect option.
SSC GD 2026 – 29 April 2026 Shift 3 · Space measurements (light year, astronomical unit)

Q32. A star 100 light-years away takes approximately 100 years for its light to reach Earth. If it explodes right now, after how long will the explosion be visible to us?

  1. (a) Immediately
  2. (b) In 100 years
  3. (c) In 1 year
  4. (d) Never
Answer & solution

Answer: (b) In 100 years

Correct Answer: In 100 years — Option (b)
If a star 100 light-years away explodes right now, the light from the explosion will take 100 years to reach Earth. We would see the explosion in 100 years from now. Scientific explanation: A light-year is the distance light travels in one year (approximately 9.461 × 10^12 km); Light travels at approximately 3 × 10^8 meters per second — the fastest anything can travel in the universe; Since the star is 100 light-years away, the light from any event at the star (including an explosion/supernova) takes exactly 100 years to reach Earth; This means: The explosion happening 'right now' at the star — we won't know about it until 100 years have passed; Conversely, when we look at a star 100 light-years away, we are seeing it as it was 100 years ago; This concept applies to all cosmic observations — we are always seeing the 'past' when we look at stars; A supernova visible from Earth has already occurred the indicated light-years ago.
Option (a) Immediately — Incorrect: Light does not travel instantaneously — it has a finite speed of approximately 3 × 10^8 m/s. Since the star is 100 light-years away, the explosion's light will take 100 years to reach Earth, NOT immediately.
Option (c) In 1 year — Incorrect: If the star were 1 light-year away, the explosion's light would reach us in 1 year; since the star is 100 light-years away, it will take 100 years (not 1 year) for the light from the explosion to reach Earth. The candidate selected this incorrect option.
Option (d) Never — Incorrect: The light from the star's explosion will eventually reach Earth — it will just take 100 years; 'never' would only apply if some physical barrier prevented the light from reaching us, which is not the case here.
RRB NTPC GL CBT-1 2025-26 – 16 March 2026 Shift 1 · Eclipses, seasons, day and night

Q33. The summer solstice occurs when the Sun is directly overhead at which of the following latitudes?

  1. (a) Equator
  2. (b) Arctic Circle
  3. (c) Tropic of Capricorn
  4. (d) Tropic of Cancer
Answer & solution

Answer: (d) Tropic of Cancer

Summer Solstice and Solar Position
Key fact 1: Summer solstice (June 20-21) occurs when
the Sun is at its northernmost position.
Key fact 2: The Tropic of Cancer is at 23.5°N latitude,
where the Sun is directly overhead during summer solstice.
Key fact 3: Tropic of Capricorn (23.5°S) receives the Sun's
direct rays during winter solstice, not summer.
Answer: Option 4 → Tropic of Cancer
RRB NTPC GL CBT-1 2025-26 – 16 March 2026 Shift 2 · Planets and their features

Q34. The acid present in the atmosphere of Venus is:

  1. (a) H₂SO₄
  2. (b) HCl
  3. (c) HNO₃
  4. (d) HCOOH
Answer & solution

Answer: (a) H₂SO₄

The atmosphere of Venus contains thick clouds of SULFURIC ACID (H ₂ SO ₄ ).
Key Facts about Venus:
• Venus is the hottest planet (avg. surface temp ≈ 465°C) — hotter than Mercury.
• Atmosphere: mainly CO ₂ (96%) + N ₂ (3.5%) + traces of SO ₂ , H ₂ SO ₄ clouds.
• Atmospheric pressure on Venus ≈ 90 times Earth's pressure.
• Greenhouse effect is extreme on Venus due to CO ₂ .
• Venus rotates east to west (retrograde rotation).
• Called Earth's twin due to similar size.
Why NOT others:
• HCl (Hydrochloric acid) → not the dominant acid in Venus clouds.
• HNO ₃ (Nitric acid) → found in Earth's stratosphere, not Venus.
• HCOOH (Formic acid) → recently detected in small amounts on Venus,
but H ₂ SO ₄ is the primary and well-established acid.
Answer: Option 1 → H ₂ SO ₄
SSC MTS 2025 – 20 February 2026 Shift 2 · Planets and their features

Q35. The earth is _____ largest planet in size in our solar system.

  1. (a) second
  2. (b) third
  3. (c) fourth
  4. (d) fifth
Answer & solution

Answer: (d) fifth

Correct Answer: fifth (Option 4)
Earth is the fifth largest planet in our solar system. The ranking by size (diameter/volume) from largest to smallest is:
1st – Jupiter
2nd – Saturn
3rd – Uranus
4th – Neptune
5th – Earth
6th – Venus
7th – Mars
8th – Mercury
Earth, while the largest of the terrestrial (rocky) planets, is only the 5th largest overall in the solar system.
SSC MTS 2025 – 19 February 2026 Shift 2 · Moons and dwarf planets

Q36. Which of the following statement is correct regarding Satellite?
I. A satellite launched by man around any planet for our own purpose is called an artificial satellite.
II. The moon is an example of artificial satellite.

  1. (a) Only I
  2. (b) Only II
  3. (c) Both I and II
  4. (d) Neither I nor II
Answer & solution

Answer: (a) Only I

The correct answer is option 1.
Statement I is correct: An artificial satellite is indeed a man-made object launched into orbit around a planet (or other celestial body) for a specific purpose such as communication, weather forecasting, navigation, or scientific research.
Statement II is incorrect: The Moon is a natural satellite of the Earth — it was not launched by humans. Natural satellites are celestial bodies that orbit a planet due to gravitational forces, while artificial satellites are man-made.
Option 2 is incorrect: Statement II is wrong because the Moon is a natural satellite, not an artificial one.
Option 3 is incorrect: Both statements cannot be correct since Statement II is factually wrong.
Option 4 is incorrect: Statement I is correct.
SSC MTS 2025 – 11 February 2026 Shift 1 · Moons and dwarf planets

Q37. As of August 2025, Jupiter has _______ moons that are officially recognized by the International Astronomical Union.

  1. (a) 111
  2. (b) 321
  3. (c) 95
  4. (d) 230
Answer & solution

Answer: (c) 95

The correct answer is 95 (Option 3). As of 2023-2025, Jupiter has 95 officially confirmed moons recognized by the International Astronomical Union (IAU), making it the planet with the most known moons in our solar system. Option 1 (111) is an overcount. Option 2 (321) is far too high. Option 4 (230) is also incorrect.
SSC MTS 2025 – 10 February 2026 Shift 1 · Planets and their features

Q38. Which of the following planet appears blue from the outer space because of its two-thirds surface is covered by water?

  1. (a) Earth
  2. (b) Mercury
  3. (c) Venus
  4. (d) Uranus
Answer & solution

Answer: (a) Earth

Correct Answer: 1 – Earth.
Earth is called the "Blue Planet" because approximately two-thirds (about 71%) of its surface is covered by water (oceans, seas, lakes, rivers). This makes Earth appear blue when viewed from outer space.
Mercury (Option 2) is a rocky, airless planet with a greyish appearance.
Venus (Option 3) appears yellowish-white due to its thick cloud cover of sulphuric acid.
Uranus (Option 4) does appear blue-green but due to methane in its atmosphere, not water coverage.
SSC MTS 2025 – 6 February 2026 Shift 3 · Space measurements (light year, astronomical unit)

Q39. The Galaxies are spread over vast distances, which are measured in _____.

  1. (a) light years
  2. (b) kilometres
  3. (c) metres
  4. (d) nanometres
Answer & solution

Answer: (a) light years

Correct Answer: 1 (light years)
Galaxies are spread over vast cosmic distances measured in light-years. One light-year is the distance light travels in one year, approximately 9.46 trillion kilometres. For even greater intergalactic distances, astronomers use megaparsecs (1 parsec = 3.26 light-years).
Option 2 (kilometres) is incorrect - kilometres are too small a unit for galactic distances.
Option 3 (metres) is incorrect - metres are used for small-scale measurements.
Option 4 (nanometres) is incorrect - nanometres (10^-9 m) are used for measuring wavelengths of light and atomic-scale distances.
SSC MTS 2025 – 5 February 2026 Shift 2 · Planets and their features

Q40. Venus is the _____ brightest object in the sky.

  1. (a) 2nd
  2. (b) 3rd
  3. (c) 4th
  4. (d) 7th
Answer & solution

Answer: (b) 3rd

Correct Answer: 3rd
Venus is the 3rd brightest object in the sky, after the Sun (1st) and the Moon (2nd). Due to its thick cloud cover that reflects about 70% of sunlight, Venus appears very bright and is often visible to the naked eye even during twilight. It is also called the 'Morning Star' and 'Evening Star'.
Why other options are wrong:
2nd - The Moon is the 2nd brightest object in the sky.
4th - Venus is brighter than any star; Jupiter is typically 4th.
7th - Much lower ranking; Venus is clearly 3rd.
Delhi Police Head Constable (Ministerial) 2025-26 – 12 January 2026 Shift 1 · Moons and dwarf planets

Q41. Why are retrograde orbits of some moons around gas giants considered strong evidence of capture rather than natural formation?

  1. (a) Retrograde motion contradicts Kepler's laws.
  2. (b) Such orbits are dynamically unstable and short-lived.
  3. (c) Moons formed in-situ would orbit in the same direction as the planet's rotation.
  4. (d) They appear only in terrestrial planets.
Answer & solution

Answer: (c) Moons formed in-situ would orbit in the same direction as the planet's rotation.

Option 3 is correct. When a moon forms naturally from the same protoplanetary disk as its parent planet, it inherits the rotation direction of the disk and orbits in the same (prograde) direction as the planet's rotation. A retrograde orbit (opposite to the planet's spin) cannot arise from in-situ formation in the same disk — it strongly suggests the moon was an independent body (asteroid or Kuiper Belt object) captured gravitationally by the planet.
• Option 1 is wrong: Retrograde orbits do not contradict Kepler's laws; Kepler's laws apply equally to prograde and retrograde orbits.
• Option 2 is wrong: While some retrograde moons are in less stable orbits, dynamical instability is not the primary reason they indicate capture over formation.
• Option 4 is wrong: Retrograde moons are found primarily around gas giants (Jupiter, Saturn, Uranus, Neptune), not terrestrial planets.
Delhi Police Head Constable (Ministerial) 2025-26 – 9 January 2026 Shift 2 · Universe, galaxies and Big Bang

Q42. How does the Doppler Effect enable the study of the expansion of the universe?

  1. (a) By measuring light interference in nearby stars.
  2. (b) By detecting a redshift in light from distant galaxies, indicating they are moving away.
  3. (c) By calculating the mass of the sun through reflected radio waves.
  4. (d) By measuring heat changes in pulsars using microwave radiation.
Answer & solution

Answer: (b) By detecting a redshift in light from distant galaxies, indicating they are moving away.

The Doppler Effect causes light from distant galaxies to appear shifted toward the red end of the spectrum (redshift), indicating those galaxies are moving away from us. This redshift is the primary observational evidence for the expansion of the universe.
(1) Light interference measures wave superposition, not cosmic expansion.
(3) The Sun's mass is calculated via gravitational methods, not radio waves.
(4) Heat changes in pulsars are unrelated to mapping universal expansion.
Delhi Police Constable (Exe) 2025-26 – 6 January 2026 Shift 3 · Planets and their features

Q43. Which planet has the longest day in the Solar System, rotating very slowly with a single rotation taking approximately 243 Earth days?

  1. (a) Venus
  2. (b) Mercury
  3. (c) Jupiter
  4. (d) Mars
Answer & solution

Answer: (a) Venus

The correct answer is (a) Venus.
Venus has the longest rotation period (sidereal day) of any planet in the Solar System — approximately 243 Earth days. Interestingly, a day on Venus (243 days) is actually longer than a year on Venus (about 225 Earth days). Additionally, Venus rotates in the opposite direction to most planets (retrograde rotation), so the Sun rises in the west and sets in the east.
(b) Mercury: While Mercury's solar day is very long (~176 Earth days), its sidereal rotation period (~59 Earth days) is shorter than Venus's 243 days; Venus has the longest rotation.
(c) Jupiter: Has the SHORTEST day of all planets — only about 10 hours; it rotates extremely fast.
(d) Mars: Mars has a day (sol) of about 24 hours 37 minutes — very similar to Earth's day; far shorter than Venus's day.
Delhi Police Constable (Exe) 2025-26 – 6 January 2026 Shift 3 · The Sun

Q44. Which layer of the Sun is primarily responsible for the formation of sunspots, appearing as dark regions due to intense magnetic activity and cooler temperatures compared to surrounding areas?

  1. (a) Photosphere
  2. (b) Chromosphere
  3. (c) Corona
  4. (d) Core
Answer & solution

Answer: (a) Photosphere

The correct answer is (a) Photosphere.
Sunspots form in the Photosphere — the visible surface of the Sun. They appear as dark regions because intense magnetic activity inhibits convection of hot plasma from below, resulting in localized areas that are cooler (about 3,500-4,500 K) compared to the surrounding photosphere (~5,500 K). This temperature difference makes them appear dark.
(b) Chromosphere: The layer above the Photosphere; features solar flares and prominences; sunspots originate in the Photosphere, not the Chromosphere.
(c) Corona: The outermost layer of the Sun extending millions of kilometers; extremely hot (1-3 million K) and visible during solar eclipses; sunspots do not originate in the Corona.
(d) Core: The innermost layer of the Sun where nuclear fusion occurs; sunspots are surface phenomena of the Photosphere, not the Core.
Delhi Police Constable (Exe) 2025-26 – 3 January 2026 Shift 2 · Asteroids, comets and meteors

Q45. The Hale-Bopp comet, visible to the naked eye in 1997, was first discovered in which year by independent astronomers?

  1. (a) 1995
  2. (b) 1986
  3. (c) 2001
  4. (d) 1990
Answer & solution

Answer: (a) 1995

The Hale-Bopp comet was simultaneously and independently discovered on July 23, 1995, by two American astronomers: Alan Hale (in New Mexico) and Thomas Bopp (in Arizona). It became known as Comet Hale-Bopp and was visible to the naked eye from 1996 to 1997, setting a record for visibility duration.
(a) Incorrect: 1986 is the year Halley's Comet last passed near Earth; Hale-Bopp was discovered in 1995.
(b) Incorrect: 2001 is after Hale-Bopp's period of visibility (1996-1997); the comet was discovered in 1995.
(c) Incorrect: 1990 is not the year of discovery; Hale-Bopp was discovered in 1995 and became widely visible in 1997.
Delhi Police Constable (Exe) 2025-26 – 29 December 2025 Shift 1 · Planets and their features

Q46. Which of the following is the primary reason for Mars' reddish color?

  1. (a) Iron oxide on the surface
  2. (b) High carbon dioxide atmosphere
  3. (c) Water ice presence
  4. (d) Sulfur compounds
Answer & solution

Answer: (a) Iron oxide on the surface

Mars appears reddish-orange because its surface soil and rocks contain large amounts of iron oxide (rust / ferric oxide, Fe2O3), which gives it the characteristic red color. That is why Mars is also called the 'Red Planet.'
(b) Incorrect: CO2 atmosphere is colorless and does not cause redness.
(c) Incorrect: Water ice is present at the poles but does not cause the overall reddish hue.
(d) Incorrect: Sulfur compounds are a major feature on planets like Venus, not the cause of Mars' color.
Delhi Police Constable (Exe) 2025-26 – 29 December 2025 Shift 3 · Planets and their features

Q47. Which planet has the 'Great Red Spot', a massive, persistent storm that has lasted over 300 years and is visible through telescopes in the planet's atmosphere?

  1. (a) Jupiter
  2. (b) Saturn
  3. (c) Neptune
  4. (d) Uranus
Answer & solution

Answer: (a) Jupiter

The Great Red Spot is a massive, persistent anticyclonic storm on Jupiter, located in its southern hemisphere. It has been observed continuously for over 300 years (first recorded in the 17th century). The storm is large enough to contain the entire Earth within it and appears red due to complex atmospheric chemistry involving sulfur and phosphorus compounds.
(b) Incorrect: Saturn has a distinctive hexagonal polar storm but not the Great Red Spot.
(c) Incorrect: Neptune has the Great Dark Spot (a transient storm), but the persistent Great Red Spot is on Jupiter.
(d) Incorrect: Uranus is known for its extreme axial tilt (98°) and featureless atmosphere; it does not have the Great Red Spot.
Delhi Police Constable (Exe) 2025-26 – 24 December 2025 Shift 1 · Stars and their life cycle

Q48. The mass of the Chandrashekhar limit is how many times the mass of the Sun?

  1. (a) 1.4 times
  2. (b) 2.8 times
  3. (c) 1.2 times
  4. (d) 1.8 times
Answer & solution

Answer: (a) 1.4 times

The correct answer is 1.4 times (Option 1).
The Chandrasekhar limit is approximately 1.4 times the mass of the Sun (about 1.4 solar masses). It is the maximum mass a white dwarf star can have before gravitational collapse causes it to become a neutron star or black hole. This limit was calculated by Indian-American astrophysicist Subrahmanyan Chandrasekhar, who won the Nobel Prize in Physics in 1983 for this work.
Option 2 - 2.8 times: This is double the actual Chandrasekhar limit; 1.4 solar masses is the accepted value.
Option 3 - 1.2 times: This underestimates the Chandrasekhar limit by 0.2 solar masses.
Option 4 - 1.8 times: This overestimates the limit; the accepted value is 1.4 solar masses, not 1.8.
Delhi Police Constable (Exe) 2025-26 – 24 December 2025 Shift 2 · Moons and dwarf planets

Q49. Which celestial body in the Solar System has the highest known albedo?

  1. (a) Europa
  2. (b) Enceladus
  3. (c) Pluto
  4. (d) Triton
Answer & solution

Answer: (b) Enceladus

The correct answer is Enceladus (Option 2).
Enceladus, Saturn's moon, has the highest known albedo (reflectivity) of any body in the Solar System, with an albedo of approximately 0.99 (reflecting nearly 99% of sunlight). Its extremely high albedo is due to its surface being covered with fresh, clean water ice and snow, constantly replenished by its cryovolcanic geysers.
Option 1 - Europa: Europa (Jupiter's moon) also has a high albedo due to its icy surface, but its albedo (~0.64) is significantly lower than Enceladus's.
Option 3 - Pluto: Pluto has a relatively high albedo (~0.49-0.72 depending on region), but this is lower than Enceladus's albedo of ~0.99.
Option 4 - Triton: Triton (Neptune's moon) has a high albedo (~0.76) due to its nitrogen ice surface, but it is still lower than Enceladus's remarkable 0.99 albedo.
Delhi Police Constable (Exe) 2025-26 – 24 December 2025 Shift 3 · Earth - shape, size and motions

Q50. How many seconds are there in 1 Solar day?

  1. (a) 86000 sec
  2. (b) 86400 sec
  3. (c) 3600 sec
  4. (d) 7200 sec
Answer & solution

Answer: (b) 86400 sec

The correct answer is 86400 sec (Option 2).
One Solar day (mean solar day) = 24 hours = 24 × 60 minutes × 60 seconds = 24 × 3600 = 86,400 seconds. The solar day is the time it takes for the Earth to rotate once relative to the Sun.
Option 1 - 86000 sec: 86000 seconds is not a standard astronomical unit; it does not correspond to one solar day.
Option 3 - 3600 sec: 3600 seconds = 1 hour , which is 1/24th of a day, not a full solar day.
Option 4 - 7200 sec: 7200 seconds = 2 hours, which is 1/12th of a day, not a full solar day.
Delhi Police Constable (Exe) 2025-26 – 23 December 2025 Shift 1 · The Sun

Q51. Which celestial body is at the center of our solar system?

  1. (a) Earth
  2. (b) Mars
  3. (c) The Sun
  4. (d) Jupiter
Answer & solution

Answer: (c) The Sun

The correct answer is The Sun (Option 3).
The Sun is the star at the center of our solar system. All planets, including Earth and Mars, orbit the Sun due to its immense gravitational pull. The Sun contains about 99.86% of the total mass of the solar system.
Option 1 - Earth: Earth is the third planet from the Sun and orbits it; Earth is not the center of the solar system (heliocentric model).
Option 2 - Mars: Mars is the fourth planet from the Sun; it orbits the Sun and is not at the center.
Option 4 - Jupiter: Jupiter is the largest planet in the solar system but orbits the Sun; it is not at the center.
Delhi Police Constable (Exe) 2025-26 – 22 December 2025 Shift 1 · Eclipses, seasons, day and night

Q52. Which phenomenon occurs due to the Earth's revolution around the Sun?

  1. (a) Formation of tides
  2. (b) Change in weather patterns
  3. (c) The length of a day
  4. (d) Occurrence of seasons
Answer & solution

Answer: (d) Occurrence of seasons

The Earth's revolution (orbital movement) around the Sun over one year, combined with the axial tilt of 23.5 degrees, causes the occurrence of seasons — summer, autumn, winter, and spring — as different hemispheres receive varying amounts of sunlight throughout the year. Option 4 is correct.
Option 1 is wrong: Formation of tides is caused by the gravitational pull of the Moon (and to a lesser extent the Sun) on Earth's oceans — this is a result of the Moon's revolution and gravity, not Earth's revolution around the Sun.
Option 2 is wrong: While seasons influence weather, the direct day-to-day change in weather patterns is caused by atmospheric factors (pressure, temperature, wind, humidity) — not directly by Earth's revolution around the Sun.
Option 3 is wrong: The length of a day (24 hours) is determined by the Earth's rotation on its own axis — not by its revolution around the Sun.
Delhi Police Constable (Exe) 2025-26 – 22 December 2025 Shift 3 · Planets and their features

Q53. Which planet has the fastest rotation in the Solar System, completing a full rotation in approximately 10 hours, giving it the shortest day among all planets?

  1. (a) Jupiter
  2. (b) Saturn
  3. (c) Neptune
  4. (d) Earth
Answer & solution

Answer: (a) Jupiter

The correct answer is Jupiter (Option 1).
Jupiter has the fastest rotation among all planets, completing one full rotation in approximately 9 hours 56 minutes, giving it the shortest day in the Solar System despite being the largest planet.
Option 2 - Saturn: Saturn also rotates quickly (approximately 10 hours 33 minutes) but not as fast as Jupiter.
Option 3 - Neptune: Completes a rotation in approximately 16 hours, much slower than Jupiter.
Option 4 - Earth: Takes approximately 23 hours 56 minutes (one sidereal day) for a full rotation, far slower than Jupiter.
Delhi Police Constable (Exe) 2025-26 – 22 December 2025 Shift 3 · Asteroids, comets and meteors

Q54. What is the name of the largest asteroid?

  1. (a) Mars
  2. (b) Jupiter
  3. (c) Ceres
  4. (d) Vesta
Answer & solution

Answer: (c) Ceres

The correct answer is Ceres (Option 3).
Ceres is the largest object in the asteroid belt between Mars and Jupiter, with a diameter of about 940 km. It is so large that it is also classified as a dwarf planet by the IAU. NASA's Dawn spacecraft visited Ceres in 2015.
Option 1 - Mars: Mars is the fourth planet from the Sun, not an asteroid. It is far larger than any asteroid.
Option 2 - Jupiter: Jupiter is the largest planet in the Solar System, not an asteroid.
Option 4 - Vesta: Vesta is the second-largest object in the asteroid belt by volume and the largest by mass after Ceres, but it is smaller than Ceres overall.
SSC Stenographer 2025 – 8 December 2025 Shift 3 · Planets and their features

Q55. Which planet has the longest day in the solar system?

  1. (a) Mars
  2. (b) Earth
  3. (c) Venus
  4. (d) Jupiter
Answer & solution

Answer: (c) Venus

The correct answer is Venus . Venus has the longest rotation period of any planet in the solar system. It takes about 243 Earth days to complete one full rotation on its axis. Interestingly, Venus rotates in the opposite direction (retrograde rotation) compared to most other planets, meaning that if you were standing on Venus, the Sun would appear to rise in the west and set in the east. Despite its long day, a Venusian year (time taken to orbit the Sun) is only about 225 Earth days , making a day on Venus longer than its year.
SSC Stenographer 2025 – 8 December 2025 Shift 3 · Universe, galaxies and Big Bang

Q56. Which type of galaxy has no regular shape and is rich in gas and dust?

  1. (a) Elliptical Galaxy
  2. (b) Lenticular Galaxies
  3. (c) Irregular Galaxy
  4. (d) Spiral Galaxy
Answer & solution

Answer: (c) Irregular Galaxy

The correct answer is Irregular Galaxy . Unlike spiral or elliptical galaxies, irregular galaxies do not have a defined shape. They appear chaotic and lack a central bulge or spiral arms. They are often rich in gas and dust, making them active sites of star formation. Examples include the Large Magellanic Cloud and the Small Magellanic Cloud, which are satellite galaxies of the Milky Way .
SSC Stenographer 2025 – 7 December 2025 Shift 1 · Earth - shape, size and motions

Q57. If a person view the Earth from above the North Pole, he will observe that the Earth rotates in:

  1. (a) No rotation
  2. (b) Random spin
  3. (c) Anti-clockwise
  4. (d) Clockwise
Answer & solution

Answer: (c) Anti-clockwise

The Earth rotates on its axis once every 24 hours, causing day and night. When viewed from above the North Pole, the direction of Earth’s rotation appears to be anti-clockwise (counter-clockwise) . This rotation is from west to east, which is why the Sun appears to rise in the east and set in the west. If someone views the Earth from above the South Pole, the rotation would appear as clockwise, but from the North Pole it is clearly anti-clockwise. Hence, the correct answer is Option 3.
SSC Stenographer 2025 – 7 December 2025 Shift 1 · Eclipses, seasons, day and night

Q58. Consider the following statements:
1. A solar eclipse – The Moon casts a shadow on Earth when it comes between the Sun and Earth.
2. A lunar eclipse – During the new moon phase, the Moon passes through the Earth’s shadow.
Which of the statements given above is/are correct?

  1. (a) Both 1 and 2
  2. (b) Neither 1 nor 2
  3. (c) 2 only
  4. (d) 1 only
Answer & solution

Answer: (d) 1 only

The correct statement is 1 only . A solar eclipse occurs when the Moon comes between the Sun and the Earth , casting its shadow on Earth, which makes the Sun partially or completely invisible from certain areas. On the other hand, the description of lunar eclipse in statement 2 is wrong. A lunar eclipse occurs not during the new moon, but during the full moon phase , when the Earth comes between the Sun and the Moon, causing the Moon to pass through Earth’s shadow. Thus, only statement 1 is correct.
SSC Stenographer 2025 – 7 December 2025 Shift 3 · Universe, galaxies and Big Bang

Q59. What evidence supports the Big Bang theory of universe origin?

  1. (a) Volcanic eruptions on Earth
  2. (b) Solar wind
  3. (c) Redshift of galaxies
  4. (d) Sunspot cycles
Answer & solution

Answer: (c) Redshift of galaxies

The correct answer is option 3. The redshift of galaxies provides strong evidence for the Big Bang theory. According to Edwin Hubble’s observations, distant galaxies appear to be moving away from us, and their light shows a shift toward the red end of the spectrum. This redshift indicates that the universe is expanding, which directly supports the idea that it originated from a singular, extremely dense and hot state about 13.8 billion years ago. Other supporting evidence includes Cosmic Microwave Background Radiation (CMBR) and the abundance of light elements like hydrogen and helium in the universe.
SSC Stenographer 2025 – 7 December 2025 Shift 3 · Stars and their life cycle

Q60. Which of the following is the correct sequence in the life cycle of a star like the Sun?

  1. (a) Nebula → Red Giant → Main Sequence → White Dwarf
  2. (b) Protostar → White Dwarf → Red Giant → Main Sequence
  3. (c) Main Sequence → Red Giant → White Dwarf
  4. (d) Red Giant → Protostar → White Dwarf
Answer & solution

Answer: (c) Main Sequence → Red Giant → White Dwarf

The correct sequence in the life cycle of a star like the Sun is Main Sequence → Red Giant → White Dwarf . A star like the Sun spends most of its life in the main sequence stage , where it fuses hydrogen into helium in its core. Once the hydrogen fuel begins to exhaust, the star expands into a Red Giant , where helium fusion and outer layer expansion occur. Finally, after shedding its outer layers, the core left behind cools and contracts into a White Dwarf , which slowly radiates away its remaining energy. This sequence applies specifically to medium-sized stars like the Sun, which do not end as supernovae but as white dwarfs.
SSC Stenographer 2025 – 6 December 2025 Shift 2 · The Sun

Q61. What are the streams of charged particles ejected by the Sun into space called?

  1. (a) Solar flares
  2. (b) Coronal loops
  3. (c) Sunspots
  4. (d) Solar wind
Answer & solution

Answer: (d) Solar wind

The correct answer is Solar wind . Solar wind refers to the continuous flow of charged particles (mainly electrons and protons) that are ejected from the outer layer of the Sun’s atmosphere, called the corona. These high-energy particles travel at very high speeds (around 400–800 km/s) and spread throughout the solar system. The solar wind interacts with Earth’s magnetic field, giving rise to spectacular natural phenomena such as auroras (Northern and Southern Lights) . It also has effects on satellite communication, GPS systems, and can even pose risks to astronauts in space. While solar flares and sunspots are solar activities, only the solar wind specifically refers to these charged particle streams.
SSC Stenographer 2025 – 6 December 2025 Shift 3 · The Sun

Q62. Which of the following systems can be affected by a solar storm?
1. GPS signal accuracy
2. Power transmission systems
3. Submarine communication cables
4. Pipeline infrastructure

  1. (a) 3 and 4 only
  2. (b) 1,2,3, and 4 all of these
  3. (c) 2 and 3 only
  4. (d) 1 and 2 only
Answer & solution

Answer: (b) 1,2,3, and 4 all of these

The correct answer is 1, 2, 3, and 4 all of these . A solar storm, also known as a geomagnetic storm, occurs when charged particles from the Sun interact with Earth’s magnetosphere. This can disrupt GPS signals by disturbing the ionosphere, which affects satellite-based navigation systems. Power transmission systems are highly vulnerable because geomagnetically induced currents (GICs) can overload transformers and lead to large-scale blackouts. Submarine communication cables , though shielded, have repeaters powered electrically, which can be disturbed by geomagnetic variations. Pipeline infrastructure can also suffer because GICs can accelerate corrosion in long pipelines, making them unsafe over time. Thus, all four systems—GPS accuracy, power grids, submarine cables, and pipelines—can be adversely affected during strong solar storms, as seen in historical events like the 1989 Quebec blackout and the Carrington Event of 1859.
SSC CHSL Tier-1 2025 – 29 November 2025 Shift 1 · Asteroids, comets and meteors

Q63. In 2024, which newly discovered 'mini-moon' was expected to orbit Earth for about two months?

  1. (a) Aditya
  2. (b) Cassini
  3. (c) 2024 PT5
  4. (d) 2024 Rosetta
Answer & solution

Answer: (c) 2024 PT5

2024 PT5 was a small asteroid discovered in 2024 that was temporarily captured by Earth's gravity as a 'mini-moon', expected to orbit Earth for about two months before escaping back into space.
Aditya is India's solar mission; Cassini was NASA's Saturn mission; 2024 Rosetta is not a real mini-moon. Hence, 2024 PT5 is correct.
SSC CHSL Tier-1 2025 – 24 November 2025 Shift 1 · Space measurements (light year, astronomical unit)

Q64. The light of the sun takes about ___ minutes to reach the earth.

  1. (a) three
  2. (b) five
  3. (c) eight
  4. (d) fifteen
Answer & solution

Answer: (c) eight

Correct Answer: eight (Option 3)
Light from the Sun takes approximately 8 minutes and 20 seconds (about 8.3 minutes, commonly stated as 8 minutes) to reach Earth. The Sun is approximately 150 million kilometres (1 AU) away from Earth, and light travels at about 299,792 km/s. 150,000,000 ÷ 299,792 ≈ 500 seconds ≈ 8.3 minutes.
Three minutes is too short — light would only cover about 54 million km in 3 minutes.
Five minutes is incorrect — that would place the Sun at about 90 million km.
Fifteen minutes is too long — that corresponds to a distance of about 270 million km.
SSC CHSL Tier-1 2025 – 22 November 2025 Shift 1 · Universe, galaxies and Big Bang

Q65. Within _____ years from the Big Bang, temperature dropped to 4500K (Kelvin) and gave rise to atomic matter. The universe became transparent.

  1. (a) 300000
  2. (b) 3000
  3. (c) 30000
  4. (d) 300
Answer & solution

Answer: (a) 300000

Correct Answer: 300000 years (Option 1)
Approximately 300,000 years after the Big Bang, the universe cooled to around 4500K (Kelvin). At this temperature, electrons combined with protons to form neutral hydrogen atoms — a process known as 'recombination'. Before this, the universe was filled with a hot, opaque plasma that scattered light. After recombination, photons could travel freely, making the universe transparent. This epoch also produced the Cosmic Microwave Background (CMB) radiation, which is still detectable today.
Why other options are wrong:
Option 2 - 3000 years: Too early; the universe was still too hot and opaque.
Option 3 - 30000 years: Still too early for recombination to occur.
Option 4 - 300 years: Far too early; the universe was extremely hot at this stage.
SSC CHSL Tier-1 2025 – 15 November 2025 Shift 3 · Space measurements (light year, astronomical unit)

Q66. What is the time taken (in minutes) for light from the Sun to reach the Earth?

  1. (a) 5.861
  2. (b) 8.311
  3. (c) 9.461
  4. (d) 12.653
Answer & solution

Answer: (b) 8.311

Light from the Sun takes approximately 8 minutes and 20 seconds (about 8.311 minutes) to reach the Earth. The average distance between Earth and the Sun is approximately 150 million km, and light travels at 300,000 km/s. Dividing: 150,000,000 ÷ 300,000 = 500 seconds = 8.33 minutes ≈ 8.311 minutes. Option 1 (5.861) is too low. Option 3 (9.461) is the distance in trillion km in a light year, not the travel time. Option 4 (12.653) is too high.
SSC CHSL Tier-1 2025 – 14 November 2025 Shift 2 · Stars and their life cycle

Q67. Which of the following statement is correct regarding Star?
I. It is made up of gases.
II. They do not have their own heat and light.

  1. (a) Only I
  2. (b) Only II
  3. (c) Both I and II
  4. (d) Neither I nor II
Answer & solution

Answer: (a) Only I

Statement I is correct: Stars are made up of gases, primarily hydrogen and helium. Nuclear fusion of hydrogen into helium in their cores generates tremendous energy. Statement II is incorrect: Stars do have their own heat and light. They are luminous, self-sustaining celestial bodies that generate energy through nuclear fusion. Therefore, Only I is correct.
SSC CHSL Tier-1 2025 – 13 November 2025 Shift 3 · Universe, galaxies and Big Bang

Q68. The most popular argument regarding the origin of the universe is the ________.

  1. (a) Big Bang Theory
  2. (b) Plate Tectonics
  3. (c) Quantum Mechanics
  4. (d) String Theory
Answer & solution

Answer: (a) Big Bang Theory

The Big Bang Theory is the most widely accepted cosmological model explaining the origin of the universe. It proposes that the universe began as an extremely hot, dense singularity approximately 13.8 billion years ago and has been expanding ever since. It is supported by evidence such as cosmic microwave background radiation and the recession of galaxies. Plate Tectonics explains Earth's crustal movement; Quantum Mechanics deals with subatomic physics; String Theory is a mathematical physics framework.
SSC CHSL Tier-1 2025 – 12 November 2025 Shift 3 · Planets and their features

Q69. According to NASA's research, which planet's rings are disappearing at a worst-case-scenario rate?

  1. (a) Saturn
  2. (b) Uranus
  3. (c) Jupiter
  4. (d) Neptune
Answer & solution

Answer: (a) Saturn

Correct Answer: Saturn
According to NASA research, Saturn's iconic rings are disappearing. In a worst-case scenario, Saturn's rings could vanish in as little as 100 million years. The rings are being pulled into Saturn by gravity as a dusty rain of ice particles. NASA's Cassini spacecraft data confirmed that Saturn is losing its rings at the maximum rate feared.
Why other options are wrong:
- Uranus: Has rings, but they are not the ones disappearing at the rates described by NASA.
- Jupiter: Has faint rings, but no significant ring-disappearance research is highlighted.
- Neptune: Also has faint rings; not the focus of NASA ring-disappearance findings.
SSC CGL Tier-1 2025 – 17 September 2025 Shift 3 · The Sun

Q70. Which of the following is NOT a consequence of space weather events like solar flares and CMEs?

  1. (a) Disruption of satellite communication
  2. (b) Blackouts in radio frequencies
  3. (c) Alteration of ocean currents
  4. (d) Damage to power grids
Answer & solution

Answer: (c) Alteration of ocean currents

Solar flares and CMEs can disrupt satellite communications, cause radio blackouts and damage power grids.
Ocean currents are driven by winds, salinity and temperature — not by space weather.
Hence 'Alteration of ocean currents' is NOT a consequence of space weather events.
SSC CGL Tier-1 2025 – 16 September 2025 Shift 3 · Stars and their life cycle

Q71. Consider these cosmic phenomena:
1. Black holes emit X-rays directly from their event horizon
2. Pulsars are rapidly rotating neutron stars
Which of the above is/are correct?

  1. (a) Statement 1 only
  2. (b) Statement 2 only
  3. (c) Both 1 and 2
  4. (d) Neither 1 nor 2
Answer & solution

Answer: (b) Statement 2 only

Statement 1 is false — X-rays from black holes come from the surrounding accretion disc and hot gas, not directly from the event horizon (no signal escapes the event horizon).
Statement 2 is true — pulsars are highly magnetised, rapidly rotating neutron stars.
Hence only Statement 2 is correct.
SSC CGL Tier-1 2025 – 14 September 2025 Shift 3 · Universe, galaxies and Big Bang

Q72. What astronomical observation is most severely hampered by increasing levels of urban light pollution?

  1. (a) Sunspots
  2. (b) Planetary transit
  3. (c) Deep-sky objects
  4. (d) Lunar phases
Answer & solution

Answer: (c) Deep-sky objects

Urban light pollution scatters artificial light into the night sky, making faint objects difficult to observe.
Deep-sky objects (galaxies, nebulae, star clusters) are very faint and require dark skies — most severely affected.
Sunspots are observed during daytime — not affected by night-time light pollution.
Lunar phases — the Moon is bright enough that light pollution does not significantly hamper observation.
Planetary transits involve bright planets — less affected.
Answer: Deep-sky objects
RRB NTPC UG CBT-1 2024-25 – 9 September 2025 Shift 1 · Eclipses, seasons, day and night

Q73. What is the main cause of different seasons on the Earth?

  1. (a) Earth's tilt and revolution around the Sun
  2. (b) Earth's distance from the Sun
  3. (c) Solar flares
  4. (d) Earth's rotation
Answer & solution

Answer: (a) Earth's tilt and revolution around the Sun

RRB NTPC UG CBT-1 2024-25 – 4 September 2025 Shift 3 · Space measurements (light year, astronomical unit)

Q74. How is the vast distance between galaxies measured?

  1. (a) In miles
  2. (b) In kilometres
  3. (c) In seconds
  4. (d) In light years
Answer & solution

Answer: (d) In light years

RRB NTPC UG CBT-1 2024-25 – 1 September 2025 Shift 1 · Latitudes, longitudes and time zones

Q75. The International Date Line approximately follows which meridian?

  1. (a) 75° W
  2. (b) 0°
  3. (c) 180°
  4. (d) 90° E
Answer & solution

Answer: (c) 180°

SSC Selection Post 2025 (Phase XIII) – 29 August 2025 Shift 1 · Planets and their features

Q76. Consider these facts about prominent solar system bodies:
1. Jupiter's Great Red Spot is a persistent anticyclonic storm.
2. Mars has two small, irregularly shaped moons.
Which of the above is/are correct?

  1. (a) Statement 1 only
  2. (b) Statement 2 only
  3. (c) Both 1 and 2
  4. (d) Neither 1 nor 2
Answer & solution

Answer: (c) Both 1 and 2

Correct Answer: Option 3 – Both 1 and 2
Statement 1 (TRUE): Jupiter's Great Red Spot (GRS) is a massive persistent anticyclonic storm — a high-pressure system rotating counter-clockwise in Jupiter's southern hemisphere — that has been observed for at least 350 years (since the 1600s). It is larger than Earth and is Jupiter's most iconic feature. Recent observations show it has been slowly shrinking.
Statement 2 (TRUE): Mars has exactly two moons — Phobos and Deimos — both of which are small and irregularly shaped (potato-like, non-spherical). Phobos (27km × 22km × 18km) and Deimos (15km × 12km × 11km) are believed to be captured asteroids from the asteroid belt. They lack the mass for gravity to pull them into spherical shapes.
Both statements are scientifically accurate.
RRB NTPC UG CBT-1 2024-25 – 29 August 2025 Shift 2 · Universe, galaxies and Big Bang

Q77. The process of planet formation through collision and sticking of small celestial bodies is called:

  1. (a) Fragmentation
  2. (b) Accretion
  3. (c) Degassing
  4. (d) Differentiation
Answer & solution

Answer: (b) Accretion

RRB NTPC UG CBT-1 2024-25 – 28 August 2025 Shift 2 · Universe, galaxies and Big Bang

Q78. Which theory suggests that planets were formed out of a cloud of material surrounding a young Sun?

  1. (a) Collision Theory
  2. (b) Binary Star Hypothesis
  3. (c) Big Bang Theory
  4. (d) Nebular Hypothesis
Answer & solution

Answer: (d) Nebular Hypothesis

RRB NTPC UG CBT-1 2024-25 – 19 August 2025 Shift 1 · Latitudes, longitudes and time zones

Q79. Which of the following is the correct longitudinal extent of the Prime Meridian?

  1. (a) 180° E
  2. (b) 90° E
  3. (c) 0°
  4. (d) 23.5° N
Answer & solution

Answer: (c) 0°

RRB NTPC UG CBT-1 2024-25 – 18 August 2025 Shift 1 · Universe, galaxies and Big Bang

Q80. Which one of the following hypotheses/theories explains the formation of the solar system from a rotating cloud of gas and dust?

  1. (a) Big Bang Theory
  2. (b) Nebular Hypothesis
  3. (c) Continental Drift Theory
  4. (d) Plate Tectonics Theory
Answer & solution

Answer: (b) Nebular Hypothesis

RRB NTPC UG CBT-1 2024-25 – 13 August 2025 Shift 1 · Earth - shape, size and motions

Q81. The Earth completes one rotation on its axis approximately in:

  1. (a) 30 days
  2. (b) 365 days
  3. (c) 24 hours
  4. (d) 12 hours
Answer & solution

Answer: (c) 24 hours

RRB NTPC UG CBT-1 2024-25 – 7 August 2025 Shift 3 · Latitudes, longitudes and time zones

Q82. Which of the following zones receives vertical rays of the Sun throughout the year?

  1. (a) Polar
  2. (b) Tropical
  3. (c) Frigid
  4. (d) Temperate
Answer & solution

Answer: (b) Tropical

SSC Selection Post 2025 (Phase XIII) – 30 July 2025 Shift 1 · Earth - shape, size and motions

Q83. Fill in the blank:
The Earth takes approximately _______ hours to complete one rotation on its own axis with respect to the sun. The period of rotation is known as the Earth day .

  1. (a) 21
  2. (b) 24
  3. (c) 25
  4. (d) 22
Answer & solution

Answer: (b) 24

Correct Answer: Option 2 – 24
The Earth takes approximately 24 hours (specifically 23 hours, 56 minutes, and 4 seconds for a sidereal day — rotation relative to distant stars; 24 hours for a solar day — rotation relative to the Sun) to complete one rotation on its own axis with respect to the Sun. This period is called the Solar Day or Earth Day. The slight difference between sidereal and solar day arises because Earth is also moving in its orbit around the Sun simultaneously.
Option 1 (21 hours): Incorrect — the Earth's rotation period is approximately 24 hours, not 21.
Option 3 (25 hours): Incorrect — 25 hours is not the Earth's rotation period.
Option 4 (22 hours): Incorrect — the rotation period is approximately 24 hours.
SSC Selection Post 2025 (Phase XIII) – 30 July 2025 Shift 2 · Eclipses, seasons, day and night

Q84. Why do seasons change throughout the year on Earth?

  1. (a) The Moon's gravitational pull
  2. (b) The tilt of the Earth's axis
  3. (c) The Earth's distance from the Sun
  4. (d) The rotation of the Earth
Answer & solution

Answer: (b) The tilt of the Earth's axis

Correct Answer: Option 2 – The tilt of the Earth's axis
Seasons occur because Earth's rotational axis is tilted at approximately 23.5° relative to its orbital plane around the Sun. This axial tilt means that as Earth orbits the Sun, different hemispheres receive varying amounts of sunlight at different times of year: when the Northern Hemisphere is tilted toward the Sun (June solstice), it experiences summer (longer days, more direct sunlight); when tilted away (December solstice), it experiences winter. The Southern Hemisphere experiences the opposite seasons simultaneously.
Option 1 (Moon's gravitational pull): The Moon's gravity primarily causes ocean tides; it does not cause seasons.
Option 3 (Earth's distance from Sun): Earth's orbit is nearly circular (eccentricity ~1.7%); Earth is actually CLOSER to the Sun in January (perihelion) than July (aphelion) — yet the Northern Hemisphere has winter in January. Distance from the Sun is NOT the cause of seasons.
Option 4 (Rotation of Earth): Earth's daily rotation (24 hours) causes day and night — not seasons.
SSC Selection Post 2025 (Phase XIII) – 29 July 2025 Shift 2 · Moons and dwarf planets

Q85. Which of the following celestial bodies is classified as a dwarf planet?

  1. (a) Jupiter
  2. (b) Earth
  3. (c) Pluto
  4. (d) Venus
Answer & solution

Answer: (c) Pluto

Correct Answer: Option 3 – Pluto
Pluto was reclassified as a 'dwarf planet' by the International Astronomical Union (IAU) on August 24, 2006. According to the IAU definition, a dwarf planet: (a) orbits the Sun, (b) has sufficient mass for gravity to make it roughly spherical, but (c) has NOT cleared the neighbourhood around its orbit. Pluto orbits in the Kuiper Belt alongside many other Kuiper Belt Objects. Other dwarf planets: Eris, Haumea, Makemake, Ceres (in the asteroid belt).
Option 1 (Jupiter): The largest planet in the Solar System — a full planet (gas giant). Has cleared its orbital neighbourhood .
Option 2 (Earth): The third planet from the Sun — a full terrestrial planet. Definitively a planet.
Option 4 (Venus): Second planet from the Sun — a full terrestrial planet, often called Earth's twin.
SSC Selection Post 2025 (Phase XIII) – 28 July 2025 Shift 1 · Eclipses, seasons, day and night

Q86. Fill in the blank:
The phenomenon where the Sun, Earth, and Moon align to cause a total or partial shadow is called a ______.

  1. (a) Eclipse
  2. (b) Transit
  3. (c) Conjunction
  4. (d) Revolution
Answer & solution

Answer: (a) Eclipse

Correct Answer: Option 1 – Eclipse
An eclipse occurs when the Sun, Earth, and Moon align such that one celestial body passes into the shadow of another. A solar eclipse occurs when the Moon comes between the Sun and Earth, casting a shadow on Earth. A lunar eclipse occurs when Earth comes between the Sun and Moon, casting Earth's shadow on the Moon. Both are characterized by the alignment described in the question.
Option 2 (Transit): A transit is when a smaller body (like Mercury or Venus) passes across the face of the Sun as seen from Earth — a different phenomenon.
Option 3 (Conjunction): Conjunction refers to when two celestial objects appear close together in the sky; does not necessarily cause shadows.
Option 4 (Revolution): Revolution is the orbital movement of a body around another (e.g., Earth around the Sun); it is not a shadow-causing phenomenon.
SSC Selection Post 2025 (Phase XIII) – 25 July 2025 Shift 1 · Planets and their features

Q87. Which planet in our solar system is known as the "Morning Star" and the "Evening Star"?

  1. (a) Mars
  2. (b) Venus
  3. (c) Mercury
  4. (d) Jupiter
Answer & solution

Answer: (b) Venus

Correct Answer: Option 2 – Venus
Venus is called both the 'Morning Star' (when visible in the eastern sky before sunrise) and the 'Evening Star' (when visible in the western sky after sunset), depending on its position in its orbit relative to Earth. Venus is the brightest natural object in the night sky after the Moon, making it easily visible to the naked eye at these times.
Option 1 (Mars): Known as the Red Planet; not called Morning/Evening Star.
Option 3 (Mercury): Though Mercury is also an inner planet (visible near the horizon), it is much fainter than Venus and is not traditionally called the Morning/Evening Star.
Option 4 (Jupiter): An outer planet; does not appear close to the Sun like Venus and is not known as the Morning or Evening Star.
SSC Selection Post 2025 (Phase XIII) – 24 July 2025 Shift 1 · Planets and their features

Q88. Which planet is known as the Red Planet?

  1. (a) Earth
  2. (b) Mars
  3. (c) Jupiter
  4. (d) Venus
Answer & solution

Answer: (b) Mars

Correct Answer: Option 2 – Mars
Mars is known as the Red Planet because its surface is covered with iron oxide (rust), giving it a distinctive reddish appearance when viewed from Earth or space. Mars is the fourth planet from the Sun and has been the focus of numerous exploration missions including NASA's Perseverance rover.
Option 1 (Earth): Called the Blue Planet due to its vast oceans.
Option 3 (Jupiter): Known as the Giant Planet; has a distinctive Great Red Spot (a storm), but is not called the Red Planet.
Option 4 (Venus): Known as the Morning Star or Evening Star; appears bright white-yellow, not red.
SSC Selection Post 2025 (Phase XIII) – 24 July 2025 Shift 1 · Universe, galaxies and Big Bang

Q89. Which of the following is classified as a galaxy?

  1. (a) Sirius
  2. (b) Orion
  3. (c) Ursa Minor
  4. (d) Andromeda
Answer & solution

Answer: (d) Andromeda

Correct Answer: Option 4 – Andromeda
Andromeda (M31) is the nearest large galaxy to our Milky Way, located approximately 2.537 million light-years away. It is a spiral galaxy and is the most distant object visible to the naked eye. It is on a collision course with the Milky Way, expected to merge in about 4.5 billion years.
Option 1 (Sirius): The brightest star in the night sky; located in the constellation Canis Major.
Option 2 (Orion): A prominent constellation (pattern of stars) in the night sky; not a galaxy.
Option 3 (Ursa Minor): A constellation containing Polaris (the North Star); not a galaxy.
SSC Selection Post 2025 (Phase XIII) – 24 July 2025 Shift 2 · Asteroids, comets and meteors

Q90. What is the asteroid belt primarily composed of?

  1. (a) Rocks and metals
  2. (b) Gases and ice
  3. (c) Liquid water
  4. (d) Volcanic magma
Answer & solution

Answer: (a) Rocks and metals

Correct Answer: Option 1 – Rocks and metals
The asteroid belt, located between the orbits of Mars and Jupiter, is primarily composed of rocky and metallic debris — remnants from the early solar system that never coalesced into a planet due to Jupiter's strong gravitational influence. The asteroids range from tiny rocks to dwarf planet Ceres (diameter ~940 km). Most are silicate (rocky) or metallic (iron-nickel) compositions.
Option 2 (Gases and ice): This describes comets or the outer solar system bodies (Kuiper Belt objects); not the asteroid belt.
Option 3 (Liquid water): No liquid water exists in the asteroid belt; some asteroids may contain water ice but not in liquid form.
Option 4 (Volcanic magma): Not applicable; asteroids are cold, solid bodies, not volcanically active.
SSC Selection Post 2025 (Phase XIII) – 24 July 2025 Shift 3 · Planets and their features

Q91. Regarding solar system planets:
1. All Jovian planets have solid surfaces.
2. Uranus's axis of rotation is nearly parallel to its orbit.
Which of the above is/are correct?

  1. (a) Statement 1 only
  2. (b) Statement 2 only
  3. (c) Both 1 and 2
  4. (d) Neither 1 nor 2
Answer & solution

Answer: (b) Statement 2 only

Only statement 2 is correct.
Explanation
❌Statement 1 is incorrect: Jovian planets (Jupiter, Saturn, Uranus, and Neptune) are gas and ice giants. They are primarily made of hydrogen, helium, and other volatile elements andlack a defined solid surface. A spacecraft would find no solid ground to land on; instead, it would sink through increasingly dense layers of gas and liquid. Only terrestrial planets (Mercury, Venus, Earth, and Mars) have solid surfaces.
✅Statement 2 is correct: Uranus is completely unique in our solar system because its axis of rotation is tilted at an extreme angle of97.77 degrees. This means its axis of rotation liesnearly parallel to its orbital plane. Essentially, Uranus rotates while virtually lying on its side as it journeys around the Sun
RRB NTPC GL CBT-1 2024-25 – 18 June 2025 Shift 1 · Latitudes, longitudes and time zones

Q92. If it is 12 noon at IST (82°30′E), what time is it approximately at 97°30′E longitude?

  1. (a) 1:00 PM
  2. (b) 1:20 PM
  3. (c) 11:00 AM
  4. (d) 12:30 PM
Answer & solution

Answer: (a) 1:00 PM

RRB Technician Grade III 2024-25 – 23 December 2024 Shift 3 · Earth - shape, size and motions

Q93. What is the value of the radius of the earth?

  1. (a) 6400 km
  2. (b) 5400 km
  3. (c) 8400 km
  4. (d) 7400 km
Answer & solution

Answer: (a) 6400 km

Correct Answer: Option 1 — 6400 km
The Earth is not a perfect sphere — it is an oblate spheroid, slightly flattened at the poles and bulging at the equator. Its mean radius is about 6371 km, which in physics numericals is always rounded to 6400 km, i.e. 6.4 × 10⁶ m.
This is the value of R used in g = GM/R² to get the acceleration due to gravity at the Earth's surface, g = 9.8 m/s². The equatorial radius is about 6378 km while the polar radius is about 6357 km; because R is smaller at the poles, g is maximum at the poles and minimum at the equator.
❌ Why the other options are incorrect
✗ 5400 km — about 1000 km too small; a radius this size would make g noticeably larger than the measured 9.8 m/s².
✗ 8400 km — far too large; the accepted radius lies between the polar 6357 km and the equatorial 6378 km.
✗ 7400 km — also too large by about 1000 km; no standard measurement of the Earth gives this figure.
📌 SSC & Railway Exam Facts
• Radius of the Earth ≈ 6400 km = 6.4 × 10⁶ m; mass of the Earth ≈ 6 × 10²⁴ kg.
• g = GM/R² = 9.8 m/s² at the Earth's surface; G = 6.67 × 10⁻¹¹ N m² kg⁻².
• g is maximum at the poles (≈ 9.83 m/s²) and minimum at the equator (≈ 9.78 m/s²).
• The shape of the Earth is called an oblate spheroid (geoid).
• Escape velocity from the Earth = 11.2 km/s; from the Moon = 2.4 km/s.

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