comets and meteors

Comets and Meteors

Comets• Large, icy dirt-ball• Contains dust, ice,

carbon dioxide, ammonia, methane and more

• Most comets ~ 16km across

Comets• Comets orbit the sun, but

have very large orbits • The orbits come from a

region beyond Pluto, called the ‘Oort Cloud’

Comets• Scientists think some comets come from a

band of icy objects called the “Kuiper belt”, beyond Neptune’s orbit

Comets• Some comets, called ‘sun-grazers’, smash right

into the sun or get so close that they break up and evaporate.

Comets• When a comet gets closer to

the sun, the ice turns into a gas cloud (called a ‘coma’)

• Solar radiation pushes dust from the sun, forming a dust tail

• Charged particles convert some of the sun’s gases, forming an ion tail

Tails always point away from the sun.

Comets• Comets leave a trail of debris behind them

that can lead to meteor showers on Earth.• Some famous comets:– Haley’s Comet– Comet Hale-Bopp– Comet Shoemaker-Levy– Comet Holmes

Meteors• Meteors (“shooting

stars”) are tiny bits of dust and space rocks that fall through the atmosphere.

• They heat up so much that they become a fiery streak across the night sky.

Meteors• Meteor showers happen

when Earth passes through a region of space that a comet passed through before

• During these times, you can see 1-2 shooting stars per minute!

Meteors• Most meteors are the size of a grain of sand• They burn up completely in the atmosphere

Meteors• Upcoming meteor showers:– Geminids, Dec.13 – Dec.14– Quadrantids, January 3– Lyrids, April 21– Eta Aquarids, May 5

Meteors• Meteors that are big enough to make it all the

way to the ground are called ‘meteorites’

Meteors• Finding one is a pretty big deal!