Solar System Leftovers

1. Solar System Leftovers Solar System Astronomy Chapter 12

2. Solar System Leftovers …really asteroids, meteorites, comets, and other debris… …still Chapter 12

3. Debris • Asteroids • small, irregular bodies • most are rock or metal • most orbit between Mars and Jupiter • some can cross Earth’s orbit • model conditions in the early Solar System (?)

4. Debris • Meteorites • pieces of asteroids that have fallen to Earth • In space it is called a meteoroid • While passing through the atmosphere, it is a meteor • If it hits, it is a meteorite • Different types: • reflect different physical conditions during formation

5. Debris • Meteorites • Different types: • Stony • Like Earth rocks • Come are carbonaceous • Iron • High concentrations of metals • Stony-iron • Can date meteorites to age of Solar System • HOW?

6. Debris • Meteorites • from microscopic dust to a few centimeters • About 2 meteorites large enough to produce visible impacts strike the Earth every day • Statistically, one meteorite is expected to strike a building somewhere on Earth every 16 months • typically impact atmosphere 10-30 km/s • ~30 times faster than a rifle bullet

7. Primitive or Processed? • Larger asteroids & planets were hot/molten during formation • Leads to differentiation • Heavy minerals sink • Some asteroids were part of differentiated bodies • So asteroids collide & fragment

8. Asteroids • Orbits • Most between Mars & Jupiter • Orbits are prograde • Orbits are not highly inclined from plane of Solar System • Orbits are not highly eccentric (circular or nearly so) • Though many NEAs have orbits crossing Earth’s

9. Asteroids • Orbits

10. Asteroids • Orbits

11. Asteroids • Orbits • Kirkwood Gaps

12. Asteroids • Orbits

13. Asteroids • Orbits

14. Beyond the Asteroid Belt

15. Trans-Neptunian Objects (TNO)

16. Comets • Big, dirty snowballs • Nucleus is ice/rock mix • ~5 km • Active near Sun • Nucleus • Coma • Ion tail • Dust tail • Comet tails point away from Sun

17. Comets • Big, dirty snowballs • Nucleus is ice/rock mix • ~5 km • Active near Sun • Nucleus • Coma • Ion tail • Dust tail • Comet tails point away from Sun

18. Comets • Big, dirty snowballs • Nucleus is ice/rock mix • ~5 km • Active near Sun • Nucleus • Coma • Ion tail • Dust tail • Comet tails point away from Sun

19. Comets • Big, dirty snowballs • Nucleus is ice/rock mix • ~5 km • Active near Sun • Nucleus • Coma • Ion tail • Dust tail • Comet tails point away from Sun Comet Hale-Bopp, 1997

20. Comets • fragmentation Shoemaker-Levy 9 Callisto Moon

21. Comets • Geology • Comet nuclei contain ices of water, carbon dioxide, methane, ammonia, etc • these should have condensed from outer solar nebula • those compounds sublime (transition from solid directly to gas phase) as comets approach sun • Densities of comet nuclei: ~0.1–0.25 g/cm3 • not solid ice balls — fluffy material, significant amounts of empty space

22. Comets • Origins • Most believed from Oort Cloud • 10-100k AU • Some from Kuiper Belt • 30-50 AU Comet Hale-Bopp, 1997

23. Impacts

24. Impacts • Chixulub

25. Impacts • Chixulub

26. Impacts • Chixulub • Mayan for “tail of the devil” • now buried beneath a kilometer-thick sequence of sediments • diameter of 145 to 180 km • object that hit ~10 km diameter • impact ~6 million times more energetic than 1980 Mt St Helens • impact ejected rock from several km beneath the surface of the Earth