Asteroids

Location: Scattered around the solar system, with most  in the asteroid belt between Mars and Jupiter Size: From about 1/2 kilometre to hundreds of kilometres across Number: Estimated at ~ 100 000 Asteroids are made of rock and metal.

Asteroids are large rocks that orbit the Sun. The drawing above is of the asteroid Gaspra.

 There are thousands of asteroids that travel around the Sun in a belt between the orbits of the planets Mars and Jupiter. Asteroids are usually so small and far away that they are difficult to see. Ceres, the largest asteroid, is nearly 900 kilometres across.

Comets

Location: At the outer edge of the solar system Number: millions of them Famous Comet: Halley's comet returns to Earth every 76 years.

Comets are huge dirty snowballs that are found in the farthest parts of the solar system. Comets are made of ice, dust, and small chunks of rock. Some comets come into the inner solar system every few hundred years and travel around the Sun. As they get close to the Sun, they give off gas that forms into a long tail  that can reach across the sky when seen from Earth.

When will Halley's comet return?

Halley's comet will next appear in the night sky in the year 2062. It orbits the sun every 75-76 years, so this is the time between appearances. Halley's comet was recorded by Edmund Halley in 1682. It was seen again in 1758, 1835, 1910, and 1986.