Asteroids & Comets

Asteroids & Comets


The chapters in this topic will look at the objects in our solar system which are much further away from the Sun and from us here on Earth. In the big, empty space between Mars and Jupiter lies a band of thousands of lumps of ice and rock called the Main Asteroid Belt. Out past Neptune there is also another large collection of these objects, called the Kuiper Belt. Like the planets, all these asteroids and comets stay in their own orbit around the sun. Sometimes, however, the giant planets near them pull them out of their orbit. 

What are asteroids and meteors?

Apart from the planets in the solar system, there are other objects that constantly orbit the sun. Two other types of objects that orbit the sun are called asteroids andmeteors.

Asteroids are much smaller than the planets, but are still very large pieces of rock and metal. Sometimes they can be huge. They are often referred to as 'mini planets' because their make-up is similar to that of some planets.

Meteors, on the other hand, resemble large stones. They are not as big as asteroids. They sometimes can be made up of dust particles only. It is believed that asteroids and meteors may have been formed from leftover matter when the solar system was originally formed.

Most meteors burn away in the atmosphere. Occasionally, some manage to pass through it. When this happens they are called meteorites. Meteorites can cause enormous damage if they strike the Earth. They can create huge holes or craters.

Almost all asteroids exist between Mars and Jupiter in an area known as the asteroid belt. Some asteroids do occasionally wander close to the sun and cross the orbit of the Earth. It is unlikely that a large asteroid would collide with the Earth, but it is not impossible. If this were to happen, the outcome would be devastating. For this reason asteroids are closely monitored.

What are comets?

Comets are balls of dirty ice and dust that also travel throughout the solar system. Many comets orbit the sun, but their orbits are extremely long. They spend most of their time in the far reaches of the solar system where we cannot see them from Earth. Occasionally, we will see a comet for a few weeks when its orbit brings it closer to the sun.

Comets are frozen solid when they are a long way from the sun. As they near the sun, the surface of the comet begins to melt and turns to gas. This then mixes with escaping dust and becomes a cloud. The sun exerts pressure on the comet which causes the dust and gases to be forced away from the centre of the comet. This creates a streaky tail on the comet. It is only when sunlight shines on the cloud that the comet becomes visible to us on Earth.