Asteroids, Comets, Meteoroids, and Craters

Small icy object that orbits the sun

3 Parts: a nucleus, a coma, and a tail

Nucleus: a core of ice rock and dust.

Coma: a cloud of dust and gas that forms when a comet gets close to the sun.

Tail: gas from the coma that trails a comet pushed by solar wind

Comets orbit the sun, in broad orbits

Halley's Comet takes 75 years to orbit the sun

The Hale-Bopp comet takes 2,533 years to orbit the sun.

Between Mars and Jupiter is a large band of asteroids

Scientists think these were dust pieces that never formed a planet

Or, they could be pieces of planets hit by asteroids

irregularly shaped rocks

Can be very large

Large asteroids are sometimes called minor planets or planetoids

Some asteroids even have a core like a planet

Ceres was once classified as an asteroid, but is now considered a dwarf planet.

Largest object in the asteroid belt

Classified as a dwarf planet

Smaller than our moon

Visited by a space craft/probeMay have water; possibility of life.

The largest asteroid in the asteroid belt

Has a crust, mantle, and a core.

Accounts for about 9 percent of the mass of all asteroids.

A shooting star is actually a meteor

A meteor is a flash of light created by a meteoroid as it burns through our atmosphere

Meteoroids are small pieces of dust or rock in space.

Scientists think they are the left by comets

There are a number of regular meteor showers

Quatranids happen in late December

Perseids happen late July through late August

Leonids and Geminids happen through November and December

A meteor that makes it to Earth is called a meteorite

There are 3 categories of meteorites: stony, iron, and stony-iron.Meteorites are very common - you can buy them.

Stony-iron are the rarest, they are made of iron, nickle and rock.

Craters are formed when large meteroids make it through Earth's atmosphere and collide with Earth

There are smaller and larger craters all over the Earth. Some are easily spotted some are hidden.

The last large crater is believed to have been formed 4000 years ago.