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The planets nearest to the sun, that is Mercury, Venus, Earth, and Mars are called Inner planets. They have the least number of moons.

Mercury

It is the closest planet to the sun. It is also the smallest planet in our solar system.

Since it’s really close to the sun, it is hard to observe it from our skies during the day. However, during sunset or sunrise, it can be seen near the horizon, if there are no buildings or trees obstructing the horizon.

There are no moons revolving around Mercury.

Venus

This planet is earth’s nearest planetary neighbour. It is also the brightest planet to

be seen in the night sky.

It can be seen in the eastern sky before sunrise or in the western sky after sunset. It’s because of this kind of appearance that it’s known as morning star or evening star, even though it is not a star.

It rotates completely opposite from the way the earth rotates around its axis. That is, it rotates from the east to the west.

Venus has no moons revolving around it.

Earth

Earth is the only planet in the solar system on which life is known to exist, thanks to the special environmental conditions – like the heat we get from the sun, the water, a comfortable atmosphere and an ozone layer that protects us from the sun’s ultraviolet rays.

Earth appears a green-blue colour from space because of the reflection of the water and the mass of land.

The earth’s axis is tilted and not perpendicular to the plane of the orbit. It is due to this that we get different types of seasons like winter, summer, autumn, and spring. The earth has only one moon.

Mars

It is the first planet outside the earth’s orbit. Because of its reddish appearance, it is

also known as the red planet. The red colour is due to the rusty colour of its soil.

Mars has two tiny natural satellites around it.

What are Outer planets?

The planets outside of the orbit of Mars, which are Jupiter, Saturn, Uranus and Neptune are called Outer planets. They have the most number of moons. They have a ring system around them.

Jupiter

It is known to be the biggest planet in the solar system. In fact, it is so large that 1300 earths can be placed in this massive planet. Its mass is to be 318 times that of the earth.

Jupiter rotates at a super-fast speed around its axis. It is said to have the largest number of satellites. It can be easily seen in the night sky due to its brightness. Four of its large moons can be seen with the help of a telescope.

Saturn

It appears yellowish in colour. What makes Saturn unique in the solar is its beautiful rings. These rings are not visible to the naked eye and can be seen only with the help of a telescope.

It is the least dense planet among all the planets. Its density is lesser than that of water. This means it can float on water.

Like Jupiter, Saturn too has a large number of satellites.

Uranus

Like Venus, Uranus rotates from east to west around its axis. Its axis is completely titled to a point where it appears to be sideways. Hence, while rotating it appears to roll on its side.

Like all the outer planets, it has many moons.

Neptune

Neptune is the farthest planet in the solar system. Its appearance is bluish and it has many moons.

 Summary

Did you know?

The Sun is the centre of the solar system and makes up 99.8 % of the mass of the entire solar system.

Also Check:

• What are Celestial objects?
• What are Stars?
• What are Constellations?