1. Which is the largest planet in our Solar System?
a) Earth
b) Saturn
c) Jupiter
d) Neptune
Answer: c) Jupiter
Explanation: Jupiter is the largest planet, with a diameter of ~142,984 km and mass more than twice that of all other planets combined.
2. The Solar System is located in which galaxy?
a) Andromeda
b) Milky Way
c) Sombrero
d) Whirlpool
Answer: b) Milky Way
Explanation: The Solar System lies in the Orion Arm of the Milky Way Galaxy.
3. The Sun accounts for about what percentage of the total mass of the Solar System?
a) 50%
b) 74%
c) 85%
d) 99.8%
Answer: d) 99.8%
Explanation: Almost all the Solar System’s mass is concentrated in the Sun.
4. Which planet is called the “Red Planet”?
a) Venus
b) Mars
c) Mercury
d) Saturn
Answer: b) Mars
Explanation: Mars appears red due to iron oxide (rust) on its surface.
5. Which planet has the most extensive ring system?
a) Jupiter
b) Saturn
c) Uranus
d) Neptune
Answer: b) Saturn
Explanation: Saturn’s rings are the most prominent and visible, though all outer gas giants have rings.
6. Which planet is known as the “Morning Star” or “Evening Star”?
a) Mars
b) Venus
c) Mercury
d) Neptune
Answer: b) Venus
Explanation: Venus is the brightest natural object in the sky after the Sun and Moon.
7. The asteroid belt lies between which two planets?
a) Mars and Jupiter
b) Earth and Mars
c) Jupiter and Saturn
d) Venus and Earth
Answer: a) Mars and Jupiter
Explanation: The asteroid belt separates the inner rocky planets from the outer gas giants.
8. Which planet is the densest in the Solar System?
a) Earth
b) Mars
c) Venus
d) Jupiter
Answer: a) Earth
Explanation: Earth has the highest density (~5.51 g/cm³).
9. What is the average distance between Earth and Sun called?
a) Light Year
b) Parsec
c) Astronomical Unit
d) Solar Constant
Answer: c) Astronomical Unit
Explanation: 1 AU = ~149.6 million km, the average Earth–Sun distance.
10. Which planet rotates on its side with an axial tilt of ~98°?
a) Neptune
b) Uranus
c) Venus
d) Saturn
Answer: b) Uranus
Explanation: Uranus rotates almost parallel to its orbital plane.
11. Which planet has the fastest rotation period?
a) Earth
b) Saturn
c) Jupiter
d) Neptune
Answer: c) Jupiter
Explanation: Jupiter rotates in ~10 hours, the shortest day among planets.
12. Which celestial object was demoted from planet status in 2006?
a) Eris
b) Ceres
c) Pluto
d) Haumea
Answer: c) Pluto
Explanation: IAU reclassified Pluto as a dwarf planet in 2006.
13. Which is the smallest planet in the Solar System?
a) Mercury
b) Mars
c) Venus
d) Pluto
Answer: a) Mercury
Explanation: Mercury is the smallest true planet with a diameter of 4,880 km.
14. The Kuiper Belt lies beyond which planet?
a) Saturn
b) Jupiter
c) Neptune
d) Uranus
Answer: c) Neptune
Explanation: The Kuiper Belt is a region of icy bodies beyond Neptune.
15. Which planet is known as the “Twin of Earth”?
a) Mars
b) Venus
c) Mercury
d) Neptune
Answer: b) Venus
Explanation: Venus is similar to Earth in size and mass, though its atmosphere is harsh.
16. Which planet has the Great Red Spot, a giant storm?
a) Saturn
b) Jupiter
c) Neptune
d) Uranus
Answer: b) Jupiter
Explanation: The Great Red Spot is a high-pressure storm lasting centuries.
17. Which planet is known as the “Ice Giant”?
a) Saturn
b) Jupiter
c) Uranus
d) Mercury
Answer: c) Uranus
Explanation: Uranus and Neptune are classified as Ice Giants due to icy compositions.
18. Which is the hottest planet in the Solar System?
a) Mercury
b) Venus
c) Mars
d) Jupiter
Answer: b) Venus
Explanation: Venus has a thick CO₂ atmosphere causing extreme greenhouse effect (~465°C).
19. Which planet has the slowest rotation?
a) Venus
b) Neptune
c) Earth
d) Saturn
Answer: a) Venus
Explanation: Venus rotates once every 243 Earth days, retrograde.
20. The largest moon of Saturn is—
a) Europa
b) Titan
c) Ganymede
d) Triton
Answer: b) Titan
Explanation: Titan is Saturn’s largest moon and second largest in the Solar System.
21. Which is the only natural satellite of Earth?
a) Phobos
b) Deimos
c) Moon
d) Titan
Answer: c) Moon
Explanation: Earth’s only natural satellite is the Moon.
22. Who proposed the heliocentric theory of the Solar System?
a) Ptolemy
b) Copernicus
c) Kepler
d) Galileo
Answer: b) Copernicus
Explanation: Copernicus (16th century) proposed the Sun-centered model.
23. Which planet has a day longer than its year?
a) Venus
b) Mercury
c) Jupiter
d) Saturn
Answer: a) Venus
Explanation: Venus’s rotation (243 days) is longer than its orbital period (225 days).
24. Which is the coldest planet in the Solar System?
a) Neptune
b) Uranus
c) Saturn
d) Pluto
Answer: b) Uranus
Explanation: Uranus has the lowest recorded atmospheric temperatures.
25. Which dwarf planet is located in the asteroid belt?
a) Pluto
b) Haumea
c) Ceres
d) Eris
Answer: c) Ceres
Explanation: Ceres is the only dwarf planet in the asteroid belt.
26. Which is the largest moon in the Solar System?
a) Titan
b) Callisto
c) Ganymede
d) Triton
Answer: c) Ganymede
Explanation: Ganymede (moon of Jupiter) is the largest moon, even bigger than Mercury.
27. The Sun produces energy through which process?
a) Nuclear fission
b) Nuclear fusion
c) Chemical combustion
d) Radioactive decay
Answer: b) Nuclear fusion
Explanation: The Sun fuses hydrogen into helium in its core, releasing massive energy.
28. Which is the brightest planet as seen from Earth?
a) Jupiter
b) Venus
c) Saturn
d) Mars
Answer: b) Venus
Explanation: Venus reflects sunlight strongly due to thick cloud cover.
29. Which planet has a blue appearance due to methane in its atmosphere?
a) Saturn
b) Uranus
c) Neptune
d) Jupiter
Answer: c) Neptune
Explanation: Methane absorbs red light, giving Neptune a deep blue color.
30. What is the shape of the orbits of planets around the Sun?
a) Circular
b) Elliptical
c) Parabolic
d) Spiral
Answer: b) Elliptical
Explanation: As per Kepler’s First Law, planets move in elliptical orbits with the Sun at one focus.
31. The Oort Cloud is believed to be the source of—
a) Asteroids
b) Short-period comets
c) Long-period comets
d) Meteoroids
Answer: c) Long-period comets
Explanation: The distant Oort Cloud contains icy bodies that produce long-period comets.
32. The Moon takes how many days to complete one revolution around the Earth?
a) 24 hours
b) 27.3 days
c) 30 days
d) 365 days
Answer: b) 27.3 days
Explanation: The Moon’s sidereal orbital period is ~27.3 days.
33. The Sun’s outermost layer is called—
a) Photosphere
b) Chromosphere
c) Corona
d) Convective Zone
Answer: c) Corona
Explanation: The corona is the Sun’s outer atmosphere, visible during a solar eclipse.
34. Which planet is called the “Windy Planet”?
a) Uranus
b) Neptune
c) Jupiter
d) Saturn
Answer: b) Neptune
Explanation: Neptune has the strongest winds in the Solar System (up to 2100 km/h).
35. Which planet has the largest number of moons discovered till now?
a) Saturn
b) Jupiter
c) Neptune
d) Uranus
Answer: a) Saturn
Explanation: As of 2025, Saturn has the most confirmed moons (145+).
36. Which is the only planet that rotates clockwise (retrograde rotation)?
a) Venus
b) Earth
c) Mars
d) Jupiter
Answer: a) Venus
Explanation: Venus rotates east to west, opposite to most planets.
37. Which celestial body is known as the “Morning Star” and “Evening Star”?
a) Mercury
b) Venus
c) Mars
d) Jupiter
Answer: b) Venus
Explanation: Venus is visible at dawn and dusk, earning both titles.
38. Meteors are also called—
a) Shooting Stars
b) Comets
c) Asteroids
d) Satellites
Answer: a) Shooting Stars
Explanation: Meteors burn up in Earth’s atmosphere, appearing as streaks of light.
39. Which is the smallest planet after Pluto’s reclassification?
a) Mars
b) Mercury
c) Venus
d) Ceres
Answer: b) Mercury
Explanation: Mercury is now the smallest official planet.
40. Which spacecraft was the first to reach interstellar space?
a) Voyager 1
b) Pioneer 10
c) Voyager 2
d) New Horizons
Answer: a) Voyager 1
Explanation: Voyager 1, launched in 1977, crossed into interstellar space in 2012.
41. The Sun is classified as which type of star?
a) Red giant
b) Yellow dwarf
c) White dwarf
d) Neutron star
Answer: b) Yellow dwarf
Explanation: The Sun is a G-type main sequence star, often called a yellow dwarf.
42. The plane in which most planets orbit the Sun is called—
a) Galactic Plane
b) Ecliptic Plane
c) Equatorial Plane
d) Orbital Plane
Answer: b) Ecliptic Plane
Explanation: The ecliptic is the plane of Earth’s orbit, nearly shared by other planets.
43. Which is the hottest part of the Sun?
a) Core
b) Corona
c) Photosphere
d) Chromosphere
Answer: a) Core
Explanation: The Sun’s core reaches ~15 million °C, where fusion occurs.
44. Which planet is called the “jewel of the Solar System”?
a) Jupiter
b) Saturn
c) Venus
d) Neptune
Answer: b) Saturn
Explanation: Saturn’s rings make it appear like a jewel in space.
45. The Great Dark Spot was observed on which planet?
a) Saturn
b) Neptune
c) Uranus
d) Mars
Answer: b) Neptune
Explanation: The Great Dark Spot is a storm system similar to Jupiter’s Red Spot.
46. Which planet has the largest volcano in the Solar System (Olympus Mons)?
a) Mars
b) Earth
c) Venus
d) Mercury
Answer: a) Mars
Explanation: Olympus Mons on Mars is ~22 km high, the tallest volcano known.
47. Which is the second largest planet in the Solar System?
a) Uranus
b) Neptune
c) Saturn
d) Earth
Answer: c) Saturn
Explanation: Saturn is the second largest, after Jupiter.
48. Which two planets are known as the “Ice Giants”?
a) Jupiter and Saturn
b) Uranus and Neptune
c) Earth and Mars
d) Venus and Mercury
Answer: b) Uranus and Neptune
Explanation: Uranus and Neptune are rich in water, ammonia, and methane ices.
49. Which planet’s atmosphere is mainly nitrogen like Earth?
a) Mars
b) Venus
c) Titan (moon of Saturn)
d) Mercury
Answer: c) Titan
Explanation: Titan’s atmosphere is ~98% nitrogen, similar to Earth.
50. What causes a solar eclipse?
a) Earth comes between Sun and Moon
b) Moon comes between Sun and Earth
c) Sun comes between Earth and Moon
d) None of these
Answer: b) Moon comes between Sun and Earth
Explanation: A solar eclipse occurs when the Moon blocks sunlight from reaching Earth.
51. The time taken by light to travel from the Sun to Earth is about—
a) 1 second
b) 8 minutes 20 seconds
c) 15 minutes
d) 1 hour
Answer: b) 8 minutes 20 seconds
Explanation: Light takes ~8 min 20 sec to cover 1 Astronomical Unit (149.6 million km).
52. Which planet is closest to the Sun?
a) Venus
b) Mercury
c) Earth
d) Mars
Answer: b) Mercury
Explanation: Mercury orbits the Sun at ~58 million km.
53. Which planet has two small moons, Phobos and Deimos?
a) Earth
b) Mars
c) Venus
d) Jupiter
Answer: b) Mars
Explanation: Mars has two irregularly shaped moons, Phobos and Deimos.
54. Which planet is tilted about 23.5°, causing seasons?
a) Mercury
b) Earth
c) Venus
d) Saturn
Answer: b) Earth
Explanation: Earth’s axial tilt (23.5°) results in seasonal changes.
55. Which planet is known for its hexagonal storm at the north pole?
a) Neptune
b) Saturn
c) Jupiter
d) Uranus
Answer: b) Saturn
Explanation: Saturn’s north pole has a stable hexagon-shaped jet stream.
56. What is the approximate age of the Solar System?
a) 1 billion years
b) 2.5 billion years
c) 4.6 billion years
d) 10 billion years
Answer: c) 4.6 billion years
Explanation: The Solar System formed ~4.6 billion years ago from a solar nebula.
57. The Sun’s visible surface is called—
a) Photosphere
b) Chromosphere
c) Corona
d) Mantle
Answer: a) Photosphere
Explanation: The photosphere emits the light we see from Earth.
58. The asteroid belt contains which dwarf planet?
a) Pluto
b) Eris
c) Ceres
d) Haumea
Answer: c) Ceres
Explanation: Ceres is the largest object in the asteroid belt.
59. Which is the only planet that supports liquid water on the surface?
a) Venus
b) Mars
c) Earth
d) Mercury
Answer: c) Earth
Explanation: Earth’s moderate temperature and atmosphere allow liquid water.
60. Which planet is sometimes called the “Earth’s twin”?
a) Venus
b) Mars
c) Neptune
d) Mercury
Answer: a) Venus
Explanation: Venus is similar in size and mass but has an inhospitable atmosphere.
61. Which planet has the shortest orbital period around the Sun?
a) Earth
b) Venus
c) Mercury
d) Mars
Answer: c) Mercury
Explanation: Mercury completes one orbit in just 88 Earth days.
62. Which is the third planet from the Sun?
a) Mars
b) Earth
c) Venus
d) Jupiter
Answer: b) Earth
Explanation: Earth is the third planet, lying between Venus and Mars.
63. Which gas is most abundant in Jupiter’s atmosphere?
a) Helium
b) Methane
c) Hydrogen
d) Oxygen
Answer: c) Hydrogen
Explanation: Jupiter’s atmosphere is ~90% hydrogen and ~10% helium.
64. What is the distance covered by light in one year called?
a) Parsec
b) Astronomical Unit
c) Light Year
d) Solar Constant
Answer: c) Light Year
Explanation: One light year is about 9.46 trillion km.
65. Which planet’s rotation is most similar to Earth’s?
a) Mars
b) Jupiter
c) Venus
d) Neptune
Answer: a) Mars
Explanation: Mars has a day of 24 hours 37 minutes, close to Earth’s 24 hours.
66. The Great Red Spot is a storm larger than Earth found on—
a) Saturn
b) Jupiter
c) Neptune
d) Uranus
Answer: b) Jupiter
Explanation: The Great Red Spot is a giant storm active for centuries.
67. The Milky Way galaxy is shaped like—
a) Elliptical
b) Irregular
c) Spiral
d) Spherical
Answer: c) Spiral
Explanation: The Milky Way is a barred spiral galaxy.
68. Which is the farthest planet from the Sun (after Pluto’s demotion)?
a) Uranus
b) Neptune
c) Saturn
d) Jupiter
Answer: b) Neptune
Explanation: Neptune is the outermost official planet.
69. The smallest dwarf planet is—
a) Haumea
b) Eris
c) Pluto
d) Ceres
Answer: d) Ceres
Explanation: Ceres is the smallest recognized dwarf planet (~950 km diameter).
70. Which space agency launched the New Horizons mission to Pluto?
a) ISRO
b) NASA
c) ESA
d) Roscosmos
Answer: b) NASA
Explanation: NASA’s New Horizons spacecraft flew past Pluto in 2015.
71. Which planet is known as the “Blue-Green Planet”?
a) Uranus
b) Neptune
c) Earth
d) Mars
Answer: a) Uranus
Explanation: Uranus appears blue-green due to methane in its atmosphere.
72. Which phenomenon explains why comets have tails pointing away from the Sun?
a) Solar Wind
b) Earth’s Gravity
c) Magnetic Fields
d) Tidal Forces
Answer: a) Solar Wind
Explanation: Charged particles from the Sun push comet tails away.
73. The Sun will eventually turn into—
a) Neutron star
b) Black hole
c) White dwarf
d) Pulsar
Answer: c) White dwarf
Explanation: After becoming a red giant, the Sun will shrink into a white dwarf.
74. Which planet is often called the “Gas Giant”?
a) Mars
b) Saturn
c) Jupiter
d) Neptune
Answer: c) Jupiter
Explanation: Jupiter is the largest gas giant in the Solar System.
75. The solar constant refers to—
a) Energy received per unit area from the Sun at Earth’s distance
b) The speed of solar wind
c) Distance of Earth from Sun
d) Sun’s surface temperature
Answer: a) Energy received per unit area from the Sun at Earth’s distance
Explanation: Solar constant ≈ 1361 W/m² at 1 AU.
76. Which is the coldest place in the Solar System?
a) Triton (moon of Neptune)
b) Pluto
c) Uranus
d) Ceres
Answer: a) Triton
Explanation: Triton’s surface temperature is about –235°C, making it the coldest known large body.
77. Which planet has the maximum surface gravity after Jupiter?
a) Neptune
b) Earth
c) Saturn
d) Venus
Answer: c) Saturn
Explanation: Saturn has strong gravity (10.4 m/s²) after Jupiter, though less dense.
78. Which planet is called the “Water Planet”?
a) Earth
b) Neptune
c) Venus
d) Uranus
Answer: a) Earth
Explanation: Earth has abundant surface water, hence called the “Water Planet.”
79. Which planet has the slowest orbital speed around the Sun?
a) Neptune
b) Saturn
c) Uranus
d) Jupiter
Answer: a) Neptune
Explanation: Neptune takes 165 years to complete one orbit, moving the slowest.
80. Which gas gives Mars its reddish appearance?
a) Methane
b) Iron oxide (rust)
c) Carbon dioxide
d) Sulphur dioxide
Answer: b) Iron oxide (rust)
Explanation: The iron-rich dust on Mars reflects sunlight in red hues.
81. Which is the smallest gas giant in the Solar System?
a) Saturn
b) Neptune
c) Uranus
d) Jupiter
Answer: b) Neptune
Explanation: Neptune is the smallest among the four gas/ice giants.
82. Which planet is sometimes called the “Evening Star”?
a) Mars
b) Venus
c) Mercury
d) Jupiter
Answer: b) Venus
Explanation: Venus is visible at dusk, hence called Evening Star.
83. Which moon of Jupiter may have a subsurface ocean, making it a candidate for life?
a) Ganymede
b) Europa
c) Callisto
d) Io
Answer: b) Europa
Explanation: Europa likely has a liquid water ocean beneath its icy crust.
84. Which spacecraft was the first to land on Mars successfully?
a) Viking 1
b) Mars Pathfinder
c) Curiosity Rover
d) Perseverance
Answer: a) Viking 1
Explanation: Viking 1 (1976) was the first successful Mars lander.
85. Which part of the Sun is responsible for solar flares and sunspots?
a) Photosphere
b) Chromosphere
c) Corona
d) Core
Answer: a) Photosphere
Explanation: Sunspots and flares originate in the photosphere due to magnetic activity.
86. Which is the densest moon in the Solar System?
a) Io
b) Ganymede
c) Titan
d) Triton
Answer: a) Io
Explanation: Io, a moon of Jupiter, is the densest moon (~3.53 g/cm³).
87. Which phenomenon causes seasons on Earth?
a) Earth’s distance from Sun
b) Earth’s axial tilt
c) Shape of orbit
d) Rotation of Earth
Answer: b) Earth’s axial tilt
Explanation: The 23.5° tilt of Earth’s axis causes seasonal changes.
88. Which is the fourth planet from the Sun?
a) Mars
b) Earth
c) Jupiter
d) Venus
Answer: a) Mars
Explanation: Mars lies between Earth and Jupiter.
89. Which is the hottest moon in the Solar System due to volcanic activity?
a) Ganymede
b) Io
c) Titan
d) Triton
Answer: b) Io
Explanation: Io, Jupiter’s moon, is the most volcanically active body.
90. Which is the nearest star to the Earth after the Sun?
a) Sirius
b) Alpha Centauri
c) Proxima Centauri
d) Betelgeuse
Answer: c) Proxima Centauri
Explanation: Proxima Centauri, 4.24 light years away, is the nearest star.
91. Which planet has the most tilted axis?
a) Earth
b) Uranus
c) Saturn
d) Venus
Answer: b) Uranus
Explanation: Uranus is tilted ~98°, making it roll on its side.
92. Which planet has day and night almost equal to its year due to slow rotation?
a) Venus
b) Mercury
c) Jupiter
d) Saturn
Answer: a) Venus
Explanation: Venus rotates once in 243 days, while its year is 225 days.
93. Which planet has the faintest ring system?
a) Jupiter
b) Saturn
c) Uranus
d) Neptune
Answer: a) Jupiter
Explanation: Jupiter’s rings are faint, discovered by Voyager 1 in 1979.
94. Which was the first planet discovered using a telescope?
a) Uranus
b) Neptune
c) Pluto
d) Saturn
Answer: a) Uranus
Explanation: Uranus was discovered by William Herschel in 1781.
95. Which planet is known as the “Morning Lantern” in some cultures?
a) Venus
b) Mars
c) Saturn
d) Jupiter
Answer: a) Venus
Explanation: Due to its brightness at dawn, Venus is called the Morning Lantern.
96. Which celestial body has geysers ejecting water-ice into space?
a) Europa
b) Enceladus
c) Titan
d) Io
Answer: b) Enceladus
Explanation: Saturn’s moon Enceladus has water-ice plumes from subsurface oceans.
97. Which planet takes the longest time to rotate once on its axis?
a) Venus
b) Mercury
c) Uranus
d) Neptune
Answer: a) Venus
Explanation: Venus rotates once in 243 Earth days, the slowest among planets.
98. Which element is the most abundant in the Sun?
a) Helium
b) Hydrogen
c) Oxygen
d) Carbon
Answer: b) Hydrogen
Explanation: The Sun is ~74% hydrogen and ~24% helium by mass.
99. Which is the outermost layer of the Sun visible during a total solar eclipse?
a) Corona
b) Photosphere
c) Chromosphere
d) Convection Zone
Answer: a) Corona
Explanation: The corona appears as a halo during a total eclipse.
100. The Solar System formed from which process?
a) Collision of stars
b) Big Bang directly
c) Nebular Hypothesis
d) Gravitational collapse of comets
Answer: c) Nebular Hypothesis
Explanation: The Solar System formed 4.6 billion years ago from a rotating gas–dust nebula.