Celestial Bodies

1. Comets, Asteroids,
and Meteoroids
Section 20.5

2. Comets
• Loose collections of ice, dust, and
small rocky particles whose orbits are
usually very long, narrow ellipses
• Comet head is made of a solid inner
core (nucleus) and a fuzzy outer layer
(coma)

3. Comets
• The coma forms when gases are
released due to getting close to the sun
• A comets tail is caused by gases
streaming away from the sun
Head
Tail

4. Comets
• Comets originate from the Kuiper belt
(outside of Neptune) or the Oort cloud
(surrounds the solar system)

5. Asteroids
• Rocky objects that are too small and
numerous to be considered planets
• Most orbit between Mars and Jupiter
(asteroid belt)
• One hit Earth 65
million years ago
• One could hit again

6. Meteors
• Meteoroid – chunk of rock or dust in space
• Meteor – a meteoroid that is burning up in
Earth’s atmosphere
• Meteorite – a meteor that doesn’t
completely burn up and hits the
ground