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