What is a planet?

The planet stands for any celestial body that moves around the sun or any other star like the sun. Planets are astronomical bodies that are massive enough to be rounded by their own gravitational force.

If we go by this definition, there can be many planets around the sun. But there are a few more criteria to fulfil before a celestial body can be classified as a planet.


For any object to be a planet, it needs to:

  • It needs to revolve around the sun.
  • It should have sufficient mass, to be round or should have enough mass to be nearly round.
  • That object should not be counted as a satellite of another planet. For example, the moon is a satellite for Earth and hence is not counted or considered a planet.
  • The area of orbit or the path along which that object will revolve around the sun should be cleared from any obstacles such as debris.


  • Planets are giant astronomical bodies that rotate around the sun in a fixed and defined path termed orbit.
  • The time taken by each of the planets to orbit around the sun or to complete 1 round around the sun is known as a year.
  • Planets orbiting around the sun also revolve around themselves.
  • The time taken by planets to revolve around themselves is termed as one day.
  • There is a total of eight planets orbiting around the sun which together with the sun forms the solar system.
  • These planets are named Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
  • Mercury is closest to Sun and Neptune is farthest from the sun.
  • Among these eight planets, Earth is the only planet that is capable of supporting human life within it.

Fun Facts:

  1. Venus is the brightest planet in our solar system.
  2. Earth has more part of water as compared to land.
  3. Jupiter is the largest planet in the solar system, yet the time period for one day is about 9 hours 55 minutes.

Additional Questions:

  1. What are dwarf planets?
  2. Explain the solar system in detail.
  3. Write about each planet and its speciality.

True or False:

  1. Planets do not revolve around anything.
  2. Jupiter is a planet.
  3. Sun is a planet.
  4. All objects rotating around the sun can be said as planet irrespective of their mass.
  5. There is a total of 12 planets in our solar system.

Objective Quiz:

  1. The path along which planets revolve around the sun is known as ______.
    1. Orbit.
    2. Year.
    3. Distance.
    4. All of the above.
  2. The time taken by a planet to revolve around the sun is known as _______.
    1. Year.
    2. Day.
    3. Month.
    4. Night.
  3. The time taken by a planet to revolve around itself is known as ______.
    1. Year.
    2. Month.
    3. Day.
    4. Hour.
  4. _______ is the planet closest to the sun.
    1. Mercury.
    2. Venus.
    3. Earth.
    4. Jupiter.
  5. _________ is the only planet capable of supporting human life on it.
    1. Earth.
    2. Jupiter.
    3. Saturn.
    4. Uranus.

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