Asteroids and Meteorites, There types and impacts

Meteorites

1. Asteroids and Meteorites

2. •Asteroids are rocky leftovers of planet formation.
•Largest is Ceres, diameter ~1,000 km
•Small asteroids are more common than large asteroids.

3. Asteroids are cratered

4. Orbits of meteorites: where do they come from?

5. Asteroids
There is a big gap between the orbits of Mars
and Jupiter.

6. Include the asteroids and it looks like this
Each dot is an asteroid

7. “Family picture” of several asteroids
52 km

8. Why is there an asteroid belt?

9. More than
150,000
asteroids at
their
predicted
locations for
Jan 1 2004

10. Why are there very few asteroids
beyond Jupiter’s orbit?
There was no rocky material beyond Jupiter’s orbit.
The heaviest rocks sank towards the center of the
solar system.
Ice could form in the outer solar system.

11. Which explanation seems to be
the most plausible?
•The belt is where all the asteroids happened to
form.
•The belt is the remnant of a large terrestrial
planet that used to be between Mars and
Jupiter.
•The belt is where all the asteroids happened to
survive.
•But why they didn’t form a little planet?

12. Rocky planetesimals
survived in the asteroid
belt between Mars and
Jupiter because they did
not accrete into a planet.
Jupiter’s gravity, stirs
up the asteroid orbits
and prevents their
planet formation.

13. How are meteorites related to
asteroids?
Meteorites are pieces of asteroids -or
sometimes planets or the Moon.

14. Peekskill, NY:
October 9, 1992

15. • Why is there an asteroid belt?
•Jupiter disrupted the orbits of planetesimals, preventing
them from accreting into a planet. Those that were not
ejected from this region make up the asteroid belt today.
•Most asteroids in other regions of the inner solar system
accreted into one of the planets.

16. COMETS

17. •Comets are icy counterparts to asteroids.
•Most comets do not have tails.
•Most comets remain frozen in the outer
solar system. Only a few enter the inner
solar system, where they can grow tails.

18. •When a comet nears the Sun, its nucleus heats
up, its ices sublimate into gas and carry off
dust, creating a coma and long tails.
•Two tails: a plasma tail of ionized gas and a
dust tail.
•Larger particles can also escape, becoming the
particles that cause meteors and meteor
showers on Earth.

21. Comets eject small particles that follow the comet around
in its orbit
This can cause meteor showers when Earth crosses the
comet’s orbit.

22. • Where do comets come from?
•Comets come from two reservoirs in the outer solar system: Kuiper
belt and Oort cloud in the region beyond Neptune.