Our Earth is one of the planets of the solar system, which is made up of the sun in the centre, nine planets including the Earth, and many smaller bodies. The smallest bodies that rotate around the sun are called asteroids, and fragments of these are meteors. Collections of dust and gas form comets.
All the objects in the solar system, including the Earth, are under the gravitational pull of the sun which holds them orbiting, or turning, around it.
The formation of the solar system
There are several ideas or theories about how the solar system was formed. One theory is that the solar system was created at the same time as the sun, which is a star, when it began to form from a giant cloud of gas. This gas drew together to form a core around which the force of gravity collected an encircling disc of left-over gas and particles of dust.
The particles which made up this disc collided with each other and caused the formation of other small solid bodies. These attracted more material fromt he disc until there was enough to form the planets. The other objects in yhe solar system, such as meteors, are the ‘rubbish’ left over fromt that time.
Our solar system is part of the universe, some of ehich we see when we look out at the night sky. No one knows just how big the universe is, but we believe it stretches farther than we can see with the best telescopes. Int he universe there are many systems like our solar system.
This theory therefore suggests that planets are formed as a result of star formation. In some cases, there are two stars in a system and, as far as we know, these have no planets, but there are plenty of single stars which we believe have planets rather like our own.
Galaxies and light years
A system of stars and planets like the one containing our solar system is called a galaxy. There are many galaxies in the universe.
There are great distances between the planets, and even the greater distances between the stars. These distances are measured in light years. One light year is the distance light travels i one year. Since light travels about 300,000 km a second, a light year is a vast distance. The sun is eight light minutes away, which means the light from the sun takes eight minutes to reach us. Looking into space we are looking backward into time. We see the sun as it was eight minutes ago and the nearest galaxy to ours, Andromeda, as it was millions of years ago.
All the objects in the solar system, including the Earth, are under the gravitational pull of the sun which holds them orbiting, or turning, around it.
The formation of the solar system
There are several ideas or theories about how the solar system was formed. One theory is that the solar system was created at the same time as the sun, which is a star, when it began to form from a giant cloud of gas. This gas drew together to form a core around which the force of gravity collected an encircling disc of left-over gas and particles of dust.
The particles which made up this disc collided with each other and caused the formation of other small solid bodies. These attracted more material fromt he disc until there was enough to form the planets. The other objects in yhe solar system, such as meteors, are the ‘rubbish’ left over fromt that time.
Our solar system is part of the universe, some of ehich we see when we look out at the night sky. No one knows just how big the universe is, but we believe it stretches farther than we can see with the best telescopes. Int he universe there are many systems like our solar system.
This theory therefore suggests that planets are formed as a result of star formation. In some cases, there are two stars in a system and, as far as we know, these have no planets, but there are plenty of single stars which we believe have planets rather like our own.
Galaxies and light years
A system of stars and planets like the one containing our solar system is called a galaxy. There are many galaxies in the universe.
There are great distances between the planets, and even the greater distances between the stars. These distances are measured in light years. One light year is the distance light travels i one year. Since light travels about 300,000 km a second, a light year is a vast distance. The sun is eight light minutes away, which means the light from the sun takes eight minutes to reach us. Looking into space we are looking backward into time. We see the sun as it was eight minutes ago and the nearest galaxy to ours, Andromeda, as it was millions of years ago.
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