Transcript meteor
Section 28.4 Asteroids, Comets and Meteoroids • Left over from nebula from when the solar system was formed. • Travel in some type of orbit. . • • mixture of ice, frozen gases and dust • • 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 Origin of Comets 1. Kuiper Belt – short period comets – up to 200 years Origin of Comets 2. Oort Cloud long period comets – up to 30 million years. 2013 Meteor Showers 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 • Rocky or metallic objects • Most orbit the Sun in the asteroid belt between Mars and Jupiter. • 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 Asteroid Eros Meteoroids • small asteroid. • Usually less than 1 mm Meteor • METEOR - meteoroid that enters earth’s atmosphere. Most burn up as a shooting star. Meteor Crater Meteorite • Meteor or part of a meteor that does not burn up entirely and falls to the ground.