13. The Inner solar system

The inner solar system is the part of the solar system that we live in. The mysterious little planets that are in the inner solar system are Mercury, Venus, Earth, and Mars. These planets are the littlest planets in the WHOLE solar system and the only solid planets, the rest are made of gas!

Mercury, Venus, Earth, and Mars are also called the rocky planets, the hot and warm planets, the inner planets and the planets closest to the sun.

Just because they are closest to the sun doesn't mean they are close to the sun, like 7km away. A planet has to go into orbit millions of kms away from the sun to avoid being burned up! For example, Earth's orbit is 150 million km away from that burning star, but, in space that is VERY close.

The inner solar system is separated from the outer solar system by the asteroid belt. The inner solar system only has 4 planets in it, half of these planets (Earth and Mars) have moons, whilst Venus and Mercury do not have moons. The names of the moons of Mars are Deimos and Phobos. They were named in 1877 by an American astronomer called Asaph Hall after the horses that pulled the chariot of the Greek god of war, Ares.

Our moon formed about 789 million years ago by big pieces of the earth floating into space. In space, these pieces of the earth stuck together and formed the moon!

One billion years ago Martian moons (mars moons) didn’t exist. They were just these asteroids flying in space. Then, two asteroids went closely past mars and he gravity of Mars caught hold of the asteroids and they went into orbit with the planet. I'm glad we live in the inner solar system where it is warm. In the next blog we are going to look at the outer solar system.