Small bodies of the Solar System
The Solar System is not only planets and moons. It also contains many smaller objects made of rock, metal, ice and dust. The three main types are meteoroids, asteroids and comets.
Asteroids and meteoroids
An asteroid is a lump of rock and metal, usually much smaller than a planet. Most asteroids orbit the Sun in a region between Mars and Jupiter called the asteroid belt. A meteoroid is a much smaller piece of rock or metal, often broken off from an asteroid or comet, that travels through space.
Key idea
When a meteoroid enters the Earth's atmosphere it burns up and produces a bright streak of light called a meteor ("shooting star"). If a piece survives and lands on the ground, it is called a meteorite.
Comets
A comet is a body made of ice, dust and rock — sometimes described as a "dirty snowball". Comets travel around the Sun in long, stretched-out orbits. When a comet comes close to the Sun, its ice heats up and turns to gas, forming a glowing tail that always points away from the Sun.
| Body | Made of |
| Asteroid | Rock and metal |
| Meteoroid | Small rock or metal |
| Comet | Ice, dust and rock |
Example
Halley's Comet passes near the Earth about once every 76 years. Each time, sunlight makes its long tail glow so it can be seen from Earth.
Remember
- Meteor = the streak of light; meteorite = the rock that lands.
- Most asteroids lie in the asteroid belt between Mars and Jupiter.
- A comet's tail always points away from the Sun.