Transcript comets
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 doughnutshaped 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.