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WHAT TO SEE
Asteroids range in size from tiny dust particles to huge worlds nearly 1,000 km (600 miles) across.
Most asteroids are oddly shaped. They aren't spherical like planets, because their gravity is too low to pull them into a round form. (This only happens when asteroids are over 250 km in size.)
Smaller ones are angular and shaped like potatoes and peanuts. The oddest looking asteroid so far is called 'Kleopatra', which looks like a 220km long dog bone.
Asteroid belt
Thousands of asteroids swarm across the 20 million miles of space between the planets Mars and Jupiter. This 'asteroid belt' marks the junction between the inner and outer Solar System and houses 90 - 95% of all asteroids.
Others orbit close to the Sun and some have been captured by the gravity of planets like Jupiter, Mars and the Earth.
Asteroids with moons
Some asteroids have others revolving around them, just as the Moon revolves around the Earth. Ida, an asteroid about 56km in diameter has its own moon - a tiny body only 1km in size. Other asteroids may well have moons of their own waiting to be discovered.
Binary asteroids
Some asteroids travel in pairs, spinning around a common centre of gravity. These are called 'binaries'. Astronomers were surprised by this, because they thought their gravity would be too weak to bind them together.
This discovery solved the age-old mystery of why impact craters often appear in pairs on the Earth, such as the Clearwater Lakes in Canada.
TRAVEL INFORMATION
Before you leave
There's no way you will be able to visit all the asteroids, so you'll have to decide which ones you want to see. Groups are usually named after the largest body they contain. For example, the Amor group that live near the Sun or the Trojans next to Jupiter.
When you arrive
Be careful if you try and land on an asteroid. Most of them spin around as they travel through space, so touchdown may be a little tricky.
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FROM THE EARTH
Although you can't see asteroids with the naked eye, a good pair of binoculars or a small telescope will help you to spot them.
Most asteroids are in stable solar orbits. However, Jupiter's gravitational field can sometimes pull bodies out of orbit, and send them off at random paths through the Solar System. Could one of these bodies strike the Earth one day?
 Find out more about the asteroid threat to Earth
Many mission have been launched from Earth to investigate these rocky remnants:
NASA's Galileo mission flew past two main belt asteroids, Ida and Gaspra, in the early 1990s en route to Jupiter
In 2000, the NEAR-Shoemaker satellite flew past asteroid Mathilde before it went into orbit around near-Earth asteroid Eros. A year later it made a soft landing on the asteroid's surface
The Deep Space 1 mission whizzed past an asteroid called Braille before reaching its main target, Comet Borrelly, in 2001
Explore the past, present and future of space exploration with our mission timeline
LOCAL HISTORY
The first asteroid was discovered by Giuseppe Piazzi in 1801. The Italian astronomer named it 'Ceres', after the Sicilian goddess of grain. Its size relative to the other asteroids has led its inclusion in a new category - the dwarf planets. There are two other dwarf planets, Pluto and Eris.
Since then, over 100,000 asteroids have been classified. There may be up to a million 1km-sized bodies in the Solar System.
Increasing numbers are being discovered by dedicated searches such as the Near Earth Asteroid Tracking system (NEAT), from Hawaii and the Space Guard programme.
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