Solar System - Practice Test 1

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.Who propounded the 'Heliocentric Theory' stating that the Sun is at the center of the solar system?

   • A.Ptolemy
   • B.Copernicus✓ Correct Answer
   • C.Kepler
   • D.Newton

   Explanation: Nicolaus Copernicus proposed the Heliocentric theory in 1543, placing the Sun at the center.

2. Q2.The Solar System formed approximately how many years ago?

   • A.13.8 billion years
   • B.4.6 billion years✓ Correct Answer
   • C.2.5 billion years
   • D.10 billion years

   Explanation: The Solar System formed about 4.6 billion years ago from the gravitational collapse of a giant molecular cloud.

3. Q3.What is the source of the Sun's energy?

   • A.Nuclear Fission
   • B.Nuclear Fusion✓ Correct Answer
   • C.Chemical Reaction
   • D.Radioactivity

   Explanation: Nuclear Fusion converts hydrogen into helium in the Sun's core, releasing immense energy.

4. Q4.The visible surface of the Sun is known as:

   • A.Corona
   • B.Chromosphere
   • C.Photosphere✓ Correct Answer
   • D.Core

   Explanation: The Photosphere is the bright, visible outer shell of the Sun.

5. Q5.Which is the nearest star to the Earth?

   • A.Proxima Centauri
   • B.Sirius
   • C.Sun✓ Correct Answer
   • D.Alpha Centauri

   Explanation: The Sun is a star and is the closest one to Earth.

6. Q6.The outermost layer of the Sun, visible only during a solar eclipse, is:

   • A.Photosphere
   • B.Corona✓ Correct Answer
   • C.Chromosphere
   • D.Radiative Zone

   Explanation: The Corona is the Sun's outer atmosphere, visible as a pearly white halo during a total eclipse.

7. Q7.Sunspots are dark patches on the Sun because they are:

   • A.Hotter than surroundings
   • B.Cooler than surroundings✓ Correct Answer
   • C.Holes in the Sun
   • D.Clouds of gas

   Explanation: Sunspots are cooler regions on the Sun's surface caused by magnetic interactions.

8. Q8.How much time does sunlight take to reach the Earth?

   • A.8 mins 16 secs✓ Correct Answer
   • B.10 mins
   • C.500 mins
   • D.8 seconds

   Explanation: It takes approximately 8 minutes and 16-20 seconds for light to travel 1 AU.

9. Q9.The Sun is primarily composed of:

   • A.Hydrogen (71%) and Helium (26.5%)✓ Correct Answer
   • B.Nitrogen and Oxygen
   • C.Carbon and Iron
   • D.Helium and Methane

   Explanation: The Sun is mainly Hydrogen (~71%) and Helium (~26.5%).

10. Q10.The temperature of the Sun's surface (Photosphere) is approximately:

    • A.6000°C✓ Correct Answer
    • B.15 million°C
    • C.4000°C
    • D.10,000°C

    Explanation: The surface temperature is about 6000°C, while the core is 15 million°C.

11. Q11.Which planet is closest to the Sun?

    • A.Venus
    • B.Mercury✓ Correct Answer
    • C.Mars
    • D.Earth

    Explanation: Mercury is the closest planet to the Sun.

12. Q12.Which planet is the smallest in the solar system?

    • A.Mars
    • B.Mercury✓ Correct Answer
    • C.Venus
    • D.Pluto

    Explanation: Mercury is the smallest planet. Pluto is a dwarf planet.

13. Q13.Which planet revolves around the Sun fastest?

    • A.Mercury✓ Correct Answer
    • B.Jupiter
    • C.Earth
    • D.Neptune

    Explanation: Mercury orbits the Sun in just 88 days.

14. Q14.Which planet has no satellite (moon)?

    • A.Mars
    • B.Mercury✓ Correct Answer
    • C.Neptune
    • D.Uranus

    Explanation: Mercury (and Venus) has no natural satellites.

15. Q15.Which planet is known as the 'Morning Star' and 'Evening Star'?

    • A.Mars
    • B.Venus✓ Correct Answer
    • C.Jupiter
    • D.Saturn

    Explanation: Venus appears brightly before sunrise and after sunset.

16. Q16.Which is the hottest planet in the solar system?

    • A.Mercury
    • B.Venus✓ Correct Answer
    • C.Mars
    • D.Jupiter

    Explanation: Venus is the hottest due to a runaway greenhouse effect caused by CO2.

17. Q17.Which planet is known as 'Earth's Twin'?

    • A.Mars
    • B.Venus✓ Correct Answer
    • C.Uranus
    • D.Neptune

    Explanation: Venus has a similar size, mass, and density to Earth.

18. Q18.Which planet rotates from East to West (Retrograde)?

    • A.Venus✓ Correct Answer
    • B.Mars
    • C.Jupiter
    • D.Saturn

    Explanation: Venus (and Uranus) rotates clockwise, meaning the Sun rises in the West.

19. Q19.Which planet has the longest day (slowest rotation)?

    • A.Mercury
    • B.Venus✓ Correct Answer
    • C.Jupiter
    • D.Earth

    Explanation: Venus takes 243 Earth days to complete one rotation.

20. Q20.The study of the Moon is called:

    • A.Selenology✓ Correct Answer
    • B.Cosmology
    • C.Geology
    • D.Areology

    Explanation: Selenology is the scientific study of the Moon.