Section 28.4 Asteroids, Comets and Meteoroids Left over from nebula from when the solar system was...
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Transcript of Section 28.4 Asteroids, Comets and Meteoroids Left over from nebula from when the solar system was...
Section 28.4 Asteroids, Comets and Meteoroids
• Left over from nebula from when the solar system was formed.
• Travel in some type of orbit..
•
• nucleus (solid – rock, metal and ice)• coma (cloud of gas and dust surrounds nucleus) • tails (dust and ionized gases). Always points away
from the sun
Orbits of Comets
• Highly elliptical• Velocity increases
greatly when they are near the Sun
• Visible only when near the sun
• Dark and virtually invisible throughout most of orbit
Why are comets important?
• Contain leftover materials that formed the planets and the Sun more than 4.5 billion years ago.
• Contain many of the organic materials thought to be essential for life
NASA's Hubble Space Telescope took this photo of Comet ISON on Oct. 9, 2013, when the comet was inside Mars’ orbit and about 177 million miles from Earth. The nucleus of ISON appears to be intact.
Meteor Showers• Earth passes through the
orbit of some comets• comet debris burns up in
Earth’s atmosphere.• predictable time each
year.• named after the
constellation they seem to originate from
• 40,000 known asteroids that are over 0.5 miles in diameter in the asteroid belt
• range in size from tiny pebbles to about 578 miles in diameter