The Solar System

by Brenda Somephikhay

The Solar System includes the Sun, the Earth (where you are now!) and all of the other planets, asteroids and comets that go around and around it.

What is the Solar System?​

​You may think that the Earth is a pretty big place, but the Earth isn’t even the biggest planet in the Solar System. The biggest planet is Jupiter – you could fit 1,321 Earths inside Jupiter. The Sun is even bigger than Jupiter – it would take 1.3 million planets the size of Earth to fill the same volume as the Sun.

1. ​Everything in the Solar System revolves around the Sun. The Sun is a star – a massive ball of hot gas that gives off light and heat.

2. There are eight planets that orbit around the Sun.

3. The closest planet to the Sun is Mercury, and the farthest away is Neptune.

4. The biggest planet is Jupiter, and the smallest planet is Mercury.

5. The Earth is the only planet that we know has creatures living on it.

6. The Earth rotates as it orbits the Sun. It takes one day to complete a rotation.

7. It takes 365 days for the Earth to complete one circuit around the Sun. We call this a year.

8. The Sun is just one of hundreds of billions of stars in the galaxy that we live in, which is called the Milky Way. The whole Universe has at least 100 billion galaxies in it.

9. You are held onto the surface of the Earth by a force called gravity. This is the same force that keeps the Earth and the other planets orbiting around the Sun.

10. Not everything in the Solar system orbits directly around the Sun. The Moon orbits around the Earth.

-The Sun is 93 million miles from the Earth. It would take Usain Bolt – the fastest man on Earth – 450 years to run from the Sun to the Earth. The Earth travels around the Sun in a loop that is shaped a bit like an oval. We call this the Earth’s orbit. The Earth is always spinning around

-There are eight planets that orbit around the Sun. In order, going from the closest planet to the Sun, to the one that is farthest away, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. All of the planets and the Sun are round, like balls.

-There is a lot of difference between the planets. Some planets like Earth are made of rock, and some like Jupiter are made of gas. The hottest planet is Venus and the coldest is Uranus.

-Mars is sometimes called ‘the red planet’ because the rocks that it is made from are red. It is the closest planet to Earth, and is slightly smaller than Earth. The biggest planet is Jupiter. Saturn is famous for having rings of small pieces of ice and dust around it. Like Jupiter, it is made of gas and is much bigger than Earth.

-The Moon is a ball of rock that orbits around the Earth, in the same way that the Earth orbits around the Sun. Is the only place in the Solar System that man has travelled to apart from Earth. Other planets have moons too. Jupiter has at least 66 of them!

​The Planets

​MERCURY

​This is the closest planet to the Sun. It is the smallest planet and is made of rock. It is so close to the Sun that it only takes 88 days for it to complete its orbit and is much hotter than Earth.

​VENUS

Venus is the next planet from the Sun after Mercury. It is also made of rock. Like Earth, Venus has an atmosphere (air) around it, but it is a lot thicker than Earth’s and Venus is permanently covered in clouds. Venus is the hottest planet and has an average temperature of 460°C. It is about the same size as Earth. It takes 225 days to travel around the Sun.

​EARTH

This is where we live! Earth is made of rock and is the only planet where water is liquid. The other planets are either too hot or too cold. Earth takes 365 days to travel around the Sun.

​MARS

Mars is a little smaller than Earth, but a lot further out. It used to have an atmosphere like Earth and Venus, but it doesn’t have very much anymore. Mars is reddish in colour and is sometimes called ‘The Red Planet’. Mars takes 687 days to complete its orbit pf the Sun and the average temperature is -63°C.

​JUPITER

Jupiter is the largest planet in the Solar System. You could fit 1,321 Earths inside Jupiter. It is made of gas and is one of the four ‘gas giants’. Jupiter has 66 moons; one of them, Ganymede, is bigger than Mercury. Jupiter is five times as far from the Sun as the Earth is and takes almost 12 years to travel around the Sun.

​SATURN

Saturn is famous for its rings. The rings were first observed (with a telescope) in 1610 by Galileo and are made up of huge numbers of small lumps of ice and dust (mostly ice). The pieces in the rings may be as small as a millimetre or as large as a few metres across. Saturn is the second largest planet in the Solar System and is another one of the ‘gas giants’ like Jupiter. It takes 29.5 years to travel around the Sun.

​URANUS

Uranus is another of the ‘gas giants’. You could fit 63 planets the size of Earth inside Uranus. Uranus takes 84 years to orbit the Sun and is the coldest planet, with an average temperature of -220°C.

​NEPTUNE

Neptune is the farthest planet from the Sun. It is 30 times as far from the sun as Earth and takes 165 years to travel around the Sun. Neptune is the last of the four ‘gas giants’ and is 58 times the volume of Earth.

NOW LET'S HAVE

SOME FUN!

Multiple Choice

What planet is this?

• Jupiter

• Saturn

• Neptune

• Earth

Multiple Choice

There are eight planets that orbit around the Sun.

• TRUE

• FALSE

Multiple Choice

This is...

• Uranus

• Venus

• Earth

Multiple Choice

Mars is sometimes called ‘the red planet’

• TRUE

• FALSE

Fill in the Blank

The biggest planet is Jupiter, and the smallest planet is _______.

Multiple Choice

Wich is the first planet next to the sun?

• Earth

• Venus

• Mercury

Fill in the Blank

The Moon is a ball of rock that orbits around the _____.

Fill in the Blank

The Earth orbits around the ___.

Fill in the Blank

Jupiter has at least 66 _____!

Multiple Choice

Is the sun a planet?

• YES!

• NO!