Asteroids, Meteoroids, and Comets

Asteroids• An asteroid is a large chunk of

rock or metal that orbits the Sun.

• The largest asteroid is Ceres with a diameter of 940 km. (Mercury has a diameter of ~4,880 km.)

Asteroids• These asteroids are leftover

debris from the formation of the solar system.

• Most orbit the Sun in the asteroid belt between Mars and Jupiter.

Meteoroids• Asteroids can collide and break

off smaller pieces.• These pieces are called

meteoroids and can be smaller than a piece of sand.

• Meteoroids are scattered throughout the solar system.

• Meteoroids that enter a planet’s atmosphere will become meteors as they streak through the sky.

• The friction caused by the atmosphere will cause some of the meteoroid to burn which produces the streak.

Meteors

• Large pieces of meteors that reach a planet’s surface are known as meteorites.

• Craters may result from impact if the meteorite is large enough.

Meteorite

• A lump of ice, frozen gas, and dust that orbits the Sun is a comet.

• Comets orbit the Sun in very long ellipses that may take it beyond the orbit of Pluto.

Comets

• Comets have three parts:A)The nucleus (core) that is a

dirty ice ball.B)The coma is the cloud of gas

that surrounds the nucleus.C)The tail is the long,

ribbonlike trail of comet dust and gas.

Comets

C) Continued….The tail always point away from the Sun.

• Comets come from the Oort Cloud that is beyond Pluto’s orbit.

Comets