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Traveling together around the Sun.

The Sun is a star and it is very important for our planet Earth.

It gives us light and heat, however Earth is not alone.

It shares the Sun with seven other planets.

Together these planets revolve around the Sun in a solar system.

Other bodies travel in this solar system such as moons, asteroids and comets.

They all move around the Sun because the Sun's gravity is very strong.

Each planet's path around the Sun is called an orbit.

The planets that are closer to the Sun have smaller orbits, so they take less time to go around it.

Mercury takes 88 days to complete one orbit.

Earth completes one orbit in 365 days or one year.

Neptune's orbit takes 60,200 days or almost 165 years.

Each planet in our solar system is unique.

For example, Mercury is the smallest planet.

It has lots of craters just like our Moon.

Jupiter is the biggest planet.

Its diameter is 11 times bigger than Earth's.

Saturn has giant rings of matter around it.

Neptune is farthest planet from the Sun.

Mars is a neighbouring planet and scientists are learning a lot about it.

They send many space probes to Mars.

A space probe called Curiosity landed on Mars on August 6, 2012.

Curiosity is as big as a car and it moves over the surface of Mars.

It recently found rocks that had strange shapes.

Running water made these shapes.

This is an important discovery.

Space probes like Curiosity continue to explore the planets, moons and other bodies in our solar system.

If technology continues to grow, we will travel to these places ourselves.

Iron and rock make up most of the four smaller inner planets of our solar system.

Gas and water make up most of the four larger outer planets.

This means that you can stand on the surface of Earth, but you can't stand on Saturn.

In fact, if you tried to stand on Saturn, you would sink down to the core of the planet.

Drawings of our solar system show the planets close to the Sun.

However, the distance between the planets and the Sun is very far.

For example, it would take 176 years to drive a car from Earth to the Sun.

It would take 5,300 years to drive from Neptune to the Sun.

Astronomers think that there are many solar systems in our Milky Way galaxy.

However, our solar system is special to us.

It is our home.

The asteroid belt.

An asteroid belt runs between the inner and outer planets.

Scientists have discovered over 7,000 asteroids there, and there may be millions more.

Asteroids travel around the Sun, just like planets.

The sister planets.

Did you know that Earth and Venus are called sister planets?

This is because they are almost the same size, and Venus is the closest planet to Earth.

However, Venus is much hotter than Earth, and it is always covered in thick clouds.