Asteroids, Comets, and Meteors
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Asteroids are rocky fragments that orbit the sun in ellipses, with the largest being Ceres. They are located mainly in the asteroid belt between Mars and Jupiter. Comets are small icy bodies that have highly elliptical orbits, originating from the Oort Cloud beyond Pluto. They develop a coma and tail when near the sun due to sublimating ice. Famous comets include Halley's Comet which returns every 76 years and Comet Hale-Bopp which returns every 5-10 years. Meteoroids are small rocky bodies that burn up as meteors in Earth's atmosphere, with some remnants surviving as meteorites on the ground.
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Asteroids, Comets, and Meteors
- 2. Asteroids • • • • Fragments of rock that orbit the sun Orbits are ellipses Largest known asteroid is Ceres Most are located in the ‘asteroid belt’ between the planets Mars and Jupiter • Composition: – Silicate minerals (look like earth rocks) – Iron and nickel (shiny metallic appearance) – Carbon (have a dark color and are rare)
- 4. Comets • Small bodies of ice, rock, and cosmic dust. • Have highly elliptical orbits around the sun. • Most originate in the Oort Cloud (spherical cloud of dust and ice that lies far beyond Pluto’s orbit and that contains the nuclei of billions of comets). • Bright appearance results from sunlight reflected by the comet’s coma • Has Several Parts: – core/nucleus – Coma (together with the core form the head of the comet) – Tail (always points a way from the sun because electrically charged particles from the sun push it away)
- 5. Famous Comets • Halley’s Comet – Passes by Earth every 76 years – Last passed Earth in 1986 – Will return in 2061 • Comet Hale-Bopp – Passes by Earth every 5-10 years – Last passed by Earth in 1997
- 6. Meteoroids • A small, rocky body that travels through space. • Most have a diameter less than 1 mm. • Most meteoroids burn up in the atmosphere due to increased friction with more molecules as it gets closer to Earth.
- 7. Meteor • Bright streak of light caused when a meteoroid burns up in the atmosphere. • Also known as “shooting stars” (click picture) • Picture to the right is a meteor shower.
- 8. Meteorite • Any part of a meteoroid that is left when a meteoroid hits Earth. • Three Types of Meteorites: – Stony (similar to rocks on Earth) – Iron (metallic in appearance) – Stony-iron (contain iron and stone, are rare)