comets

• Comets• “dirty snowballs” in space

• Contain• Dust• Gases• CO2

• CH4

• NH3

• Leftovers from the beginning of the solar system 4.6 billion years ago

Parts of a comet

• Head • Nucleus – fragments of rock (silicates

and metals ) and frozen gases• Coma – envelope of vaporized H2

gas• Tail – vaporized gas and dust

• Sunlight reflects from the vapor• Ionized gases tail• Dust tail• Solar wind pushes the vapor in a

direction away from the sun• comet tails generally point away from

the Sun.

tail

• As the tail approaches the sun• Tail grows longer• Tail points away from the sun

• Comet’s orbit – extremely elliptical

continues in orbit to outside of the solar system called the oort cloud where it picks up more dust, rocks and gases.

Oort cloud

• Belt of material outside of the solar system where comets pick up gas and dust to rebuild its nucleus and coma.

• The Kuiper Belt and the Oort Cloud surround our sun, a star. • The Kuiper Belt is a doughnut-

shaped ring, extending just beyond the orbit of Neptune from about 30 to 55 AU. • The Oort Cloud is a spherical

shell, occupying space at a distance between five and 100 thousand AU.

• Long-period comets (which take more than 200 years to orbit the sun) come from the Oort Cloud.

• Short-period comets (which take less than 200 years to orbit the Sun) originate in the Kuiper Belt.

Sometime over the next week or so, you may want to pick a clear evening to head outside and look at the sky. If you do, you'll have a chance to see something pretty cool: a comet, streaking past Earth as it orbits the sun.The comet, called C/2014 Q2 (Lovejoy), appears as a beautiful, fuzzy green ball through binoculars, and in some areas, it's even visible to the naked eye.