UPSC Prelims 2003 Q126: Science & Technology – Space Technology & Astronomy
Among the following which planet takes maximum time for one revolution around the
Sun?
- (a) Earth
- (b) Jupiter
- (c) Mars
- (d) Venus
Answer: (b) Jupiter
Explanation
Planet taking the longest time to orbit the Sun
| Planet | Period of revolution |
|---|---|
| Jupiter | About 11.9 years, the longest of these |
| Mars | About 1.9 years |
| Earth | 1 year |
| Venus | About 0.6 year (225 days) |
Among the planets listed, Jupiter takes the maximum time, about 11.9 years, for one revolution around the Sun.
Answer: (b) Jupiter.
Why each option is right or wrong
- (a) Incorrect. The Earth takes one year for a revolution.
- (b) CORRECT. Jupiter takes about 11.9 years.
- (c) Incorrect. Mars takes about 1.9 years.
- (d) Incorrect. Venus takes about 225 days.
Key point
Kepler's third law: period grows with the orbital distance; Neptune takes about 165 years.
Remember
Jupiter takes about 12 years to go round the Sun once.
Common mistakes
- Choosing Mars because it is next to Earth.
- Mixing up rotation with revolution of a planet.
- Forgetting that the outer planets take longer.
Exam tip
The farther the planet, the longer the revolution period.
Sources
- NCERT Class VIII Science — Stars and the Solar System
- NASA — Jupiter Fact Sheet (Goddard Space Flight Center, Planetary Fact Sheets)