Small pieces of rock or metal that travel through space around the Sun, and are smaller than asteroids, are called:

Meteoroids are small rocky or metallic bodies moving through space, ranging in size from tiny dust grains to objects about one metre across. They are much smaller than asteroids.

Meteoroid, meteor and meteorite:

Meteoroid: the small body while it is in space.

Meteor: the streak of light seen in the sky when a meteoroid enters the Earth's atmosphere at high speed and burns up because of friction with the air. Meteors are commonly called "shooting stars" or "falling stars", though they are not stars.

Meteorite: a piece of the meteoroid that survives the passage through the atmosphere and lands on the Earth's surface.

Very bright meteors are called fireballs, and those that explode in the atmosphere are called bolides.

Where meteoroids come from:

• Most are fragments of comets or asteroids.
• Some are pieces knocked off the Moon or Mars by impacts.

Meteor showers:

When the Earth passes through a stream of debris left by a comet, many meteors are seen in a short time. This is a meteor shower.

Types of meteorites:

• Stony meteorites: made mostly of silicate minerals; the most common type.
• Iron meteorites: made mostly of iron and nickel.
• Stony-iron meteorites: a mixture of both.
• Meteorites are very valuable to scientists, because many of them are about 4.6 billion years old and preserve material from the early solar system.

Impact craters:

Large meteorites can create craters. An example is the Barringer Crater (Meteor Crater) in Arizona, USA.

About 66 million years ago, a large asteroid impact near Chicxulub in Mexico is believed to have caused the extinction of the dinosaurs.

The Chelyabinsk meteor exploded over Russia in 2013, injuring over 1,000 people, mostly from broken glass.

Why not the other options?

• ✗Comets are icy bodies that form tails near the Sun.
• ✗Planets are large bodies that orbit the Sun and have cleared their orbits.
• ✗Satellites are objects that orbit planets.