1. Amor asteroid

• -an asteroid whose orbit crosses the orbit of Mars

2. Apollo asteroids

• asteroids whose orbits cross the orbit of Earth.

3. asteroid

• rocky bodies orbiting between the orbits of Mars and Jupiter

4. asteroid belt

• area between Mars and Jupiter where the majority of asteroids can be found.

5. binary asteroid

• large asteroid orbited by a smaller satellite body.

6. carbonaceous asteroid

• a darker asteroid containing more carbon than most asteroids.

7. carbonaceous chondrite

• a carbonaceous asteroid containing chunks of rocky material (chondrules).

8. carbonaceous meteorite

• dark meteorite with high carbon content.

9. chondrule

• rocky materials embedded in the interiors of some carbonaceous meteorites.

10. coma

• brightest part of a comet, often called the ‘head’ of the comet.

11. comet

• a small body, composed mainly of ice and dust, in an elliptical orbit about the Sun.

12. differentiated meteorite

• a meteorite where the denser materials have moved to the center, usually as a result of strong heating in the past, indicating the meteorite was heated by geologic activity or by a collision.

13. dust tail

• - comet’s tail composed of dust.

14. fall

• meteorite discovered on the ground after being seen in the sky.

15. find

• meteorite discovered on the ground without being seen in the sky.

16. Hirayama family

• a group of asteroids having the same orbit.

17. hydrogen envelope

• invisible region around a comet extending millions of kilometers into space.

18. ion tail

• stream of ionized gas pushed away from the head of a comet by the solar wind. (plasma tail)

19. iron meteorite

• meteorite composed mainly of iron-nickel, high-density.

20. Kirkwood gaps

• gaps in spacing of orbits of asteroids, caused by gravitational resonance.

21. meteor

• a piece of interplanetary debris entering the Earth’s atmosphere and burning up.

• A ‘shooting star’.

22. meteor shower

• many meteors seen each hour, caused by Earth moving through cometary debris.

23. meteorite

• part of a meteoroid that survives the atmosphere and lands on Earth

24. meteoroid

• interplanetary debris prior to entering the Earth’s atmosphere

25. meteoroid swarm

• pebble-sized cometary fragments moving in the same orbit as the parent comet.

26. micrometeoroid

• interplanetary debris from dust-sized to pebble-sized.

27. nucleus

• solid region of ice and dust that makes up the head of the comet.

28. Oort cloud

• material surrounding the solar system, out to about 50,000 A. U. where comets originate.

29. plasma tail

• ion tail.

30. primitive meteorite

• a stone meteorite showing no evidence of heating in the past.

31. radiant

• constellation from whose direction a meteor shower appears to come.

32. stone meteorite

• composition comparable to that of terrestrial rocks.

33. stony-iron meteorite

• a mixture of iron and stone.

34. S-type asteroid

• made of silicate, or rocky material.

35. Sun-grazing comet

• a comet whose orbit takes it very close to the Sun, at which point it may be destroyed.

36. Trojan asteroid

• asteroids locked into Lagrange points with Jupiter, in the same orbit as Jupiter, 60 degrees ahead of and behind the planet.

37. type I tail

• ion tail, plasma tail; made of ionized gases, straight.

38. type II tail

• dust tail; broad, diffuse, and curved.

1. What is the evidence of a high potential for collisions of asteroids with Earth?

• Apollo asteroids cross Earth’s orbit

• there are several dozen craters on Earth that may have been impact sites

• other inner planets and moons show impact sites.

2. What are Trojan asteroids?

• asteroids locked into Lagrange points with Jupiter, in the same orbit as Jupiter, 60 degrees ahead of and behind the planet.

3. What are comets like when they're far from the Sun? What happens when they come into the inner solar system?• ‘Dirty snowballs’.

• The solar energy causes the ice to sublime.

4. What are the two types of comet tails?

• Type I tails, ion tails, plasma tails. Straight, made of ionized gasses.

• Type II tails, dust tails. Curved, made of dust.

5. What are some possible fates of comets?

• Can be broken up when near the Sun.

• Can crash into the Sun.

• Can gradually lose matter with each trip past the Sun.

• Can be pulled out of orbit and crash into another body (a planet).

6. Explain the difference between a meteor, a meteoroid, and a meteorite. • A meteoroid is debris before it enters the

atmosphere;

• a meteor is debris that has entered the atmosphere;

• a meteorite is a part of a meteor that survives to hit the surface.

7. What causes a meteor shower?

• The Earth passing through a young, relatively undispersed cluster of meteoroids (comet fragments).

8. What are the various types of meteorites?

• Differentiated meteorites,

• primitive meteorites,

• carbonaceous meteorites,

• carbonaceous chondrites.

9. What are the most primitive meteorites?

• Carbonaceous chondrites.

10. What have meteorites revealed about our solar system?

• Being so old, they reveal the type of materials present at the formation of the solar system.