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Space^23

A meteor, or shooting star, is a streak of light in the sky

caused by a piece of dust or rock from space burning up

in Earth’s atmosphere. Space rocks that hit Earth are

called. METEORITES.

An asteroid is a lump of rock that circles the

Sun. Asteroids are also called minor

planets. The biggest one, Ceres,

is 930 km (578 miles) across.

WHAT IS THE ASTEROID BELT?

Most asteroids circle the Sun in a broad band

between Mars and Jupiter called the asteroid belt,

which is about 345 million km (214 million miles)

wide. The asteroids are pieces left over from when the

major planets formed from small chunks of rock.

Some of the asteroids travel outside the belt, moving

out towards Saturn or in towards Earth. Asteroids that

come close to Earth are called Near-Earth Objects.

WHAT ARE ASTEROIDS MADE OF?

There are three main kinds of asteroids,

made up of rock, or metal, or a mixture

of the two. The rocky ones, known as

carbonaceous (C-types), are usually dark

and difficult to spot. The lighter-coloured

ones, known as silicaceous (S-types), contain

some metal. The pure metal M-types are the

brightest and rarest.

WHAT IS A METEOR SHOWER?

In a meteor shower, we see more meteors

than usual coming from one patch of sky. Most

showers take place on the same date every year –

the Orionids, for example, are in October, when Earth

passes through the dusty trail of Halley’s Comet.

WHAT ARE METEORITES MADE OF?

Most of the 3,000 meteorites that hit Earth each year

are lumps of stone. The rest are mainly metal, made

of iron-nickel and small amounts of other minerals.

A meteorite is a lump of space rock or

metal, usually from an asteroid, that hits

the surface of Earth, often leaving a crater.

FIND OUT MORE. Comets 22 • Rocks 46–47

NEAR-EARTH

OBJECT 3

The asteroid Eros is

33 km (21 miles) long. If

an object like Eros collided

with Earth, the results would be

catastrophic for the whole planet.

FIND OUT MORE. Jupiter 19 • Solar System 14

SHOOTING STARS 3

During a meteor shower, you

might spot dozens of meteors.

They seem to come from the

same spot in the sky, which is

called the radiant.

METEORITES

1 METEOR CRATER

A meteorite 30 m (100 ft) wide

made the 1.2-km- (0.7-mile-) wide

Meteor Crater in Arizona, USA.

1 STONY METEORITE

This stony meteorite has a dark

crust, showing where it melted

as it fell through the atmosphere.

1 IRON METEORITE

This cut and polished iron-nickel

meteorite collided with Earth

about 50,000 years ago.

Jupiter

Asteroid

belt

Mars

ASTEROIDS

Asteroids

METEORS

Meteors

rocks that hit

Most D

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meteors

asteroids