Comets, Meteors, & Asteroids

1. Comets, Meteors, & Asteroids

2. 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.

3. Halley’s Comet

4. Halley’s Comet

5. 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.

6. 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.

7. 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.

8. Comet Structure

9. 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.

10. Meteoroids, Meteor, Meteorites

11. Meteorite

12. 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.

13. Asteroids

14. Asteroids

15. Asteroids

16. Asteroids • Asteroid sizes can range from tiny particles to 940 km. • Ceres is the largest and first asteroid discovered.

17. Asteroids Vesta-2nd largest asteroid (530 km)

18. Asteroids Pallas-3rd largest asteroid (522 km)

19. Asteroids 10 Hygiea-4th largest asteroid (430 km)

20. Asteroids Gaspraphotographed by Galileo on its way to Jupiter.