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Comets, Meteors, & Asteroids. Comets. A comet is composed of dust, rock, ice, methane, and ammonia. Halley’s comet, named after astronomer Edmund Halley, was last seen from Earth in 1986. It takes 76 years to orbit the sun. Halley’s Comet. Halley’s Comet. Oort Cloud.
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Comets • A comet is composed of dust, rock, ice, methane, and ammonia. • Halley’s comet, named after astronomer Edmund Halley, was last seen from Earth in 1986. It takes 76 years to orbit the sun.
Oort Cloud • The Oort cloud is a cloud of comets that surround the solar system beyond Pluto. • Comets either escape the gravity of solar system objects or get captured in smaller orbits.
Comet Hale-Bopp Discovered July 23, 1995, it was the brightest comet visible from Earth in 20 years. It was at its brightest in March and April 1997.
Comet Structure As a comet approaches the Sun ice, methane, and ammonia vaporize releasing dust and jets of gas that form a bright cloud called a coma around the solid part (nucleus). Solar winds push the gases and dust away from the Sun to create tails.
Meteoroids, Meteor, Meteorites • Dust and rock, sometimes broken off from comets. • Most meteoroids that enter Earth’s atmosphere burn up. When that happens it is called a meteor. • If the meteoroid is large enough to not burn up completely and it strikes Earth it is called a meteorite.
Asteroids • An asteroid is a piece of rock similar to the material that formed the planets. • Most asteroids are in a belt between the orbits of Mars and Jupiter. • Some asteroids get thrown out of the belt by Jupiter’s gravity. Scientists monitor these asteroids as they near Earth.
Asteroids • Asteroid sizes can range from tiny particles to 940 km. • Ceres is the largest and first asteroid discovered.
Asteroids Vesta-2nd largest asteroid (530 km)
Asteroids Pallas-3rd largest asteroid (522 km)
Asteroids 10 Hygiea-4th largest asteroid (430 km)
Asteroids Gaspraphotographed by Galileo on its way to Jupiter.