1. UNIT 4: MEMBERS OF THE SOLAR SYSTEM PART IV: VAGABONDS OF THE SOLAR SYSTEM

2. Dwarf Planets Pluto, Eres, Ceres Small Solar System Bodies (SSSB’s) Comets Asteroids Meteoroids

3. Comets ( Dirty Snowballs in Space) Composition: frozen water and other ices, rock fragments Origin: Left over material from formation of SS Location: Oordt cloud (sphere of material beyond Kuiper Belt)

5. The Structure of A Comet Nucleus - rocky, icy core Coma – outer vaporize region Tail – ionized material from coma. Formed by comet encounters solar wind

6. Nucleus of Comet Halley (Photo by Giotto spacecraft)

7. Tail of Comet Ikeya-Seki

8. Comet Kohoutek

9. Comet West

10. Highly elliptical orbits (eccentricity over.5) Coma and Tail form as it is warmed by sun. Tail always points away from Sun Comets do last forever. Each passing by the Sun, comet is reduced. The Orbit & Tails of Comets

11. The Two Tails of Comet Mrkos

12. Comet Brooks

13. Comet Hale-Bopp

14. Asteroids Large rocky fragments left over from the formation of the solar system Composition: Most aredark and carbon-silica rich Origin: Remnants from formation of Solar System

15. Asteroid Locations 1.Asteroid Belt Near-Circular orbit Most located 2- 3.5 AU’s from the sun (Between Mars & Jupiter Over 90,000 have been confirmed to exist Avg. separation btw. asteroids estimated at 6 million miles

16. 2.Apollo Bodies Highly elliptical orbit Cross Earth’s orbit

17. 3. Trojan Asteroids 2 location on Jupiter’s orbit

18. Green – Asteroid Belt Red – Pass w/in 1.3 AU’s of sun Dark Blue – Trojan asteroids ALL KNOWN ASTEROIDS

19. Ceres Discovered: 1801 Diameter: ~600 miles Density: 2.2 g/cm 3 Rotation Pd. : 9 h Largest body in the Asteroid Belt

20. Comparison of Ceres with the Moon and Earth

21. Composition: Crust: dust & icy mix Mantle: ice Core: Rocky

22. Location and Orbit of Ceres

23. Asteroid Eros (Photos taken by Near Earth Asteroid Rendevous Shoemaker spacecraft)

24. Asteroid Ida and its satellite Dactyl

25. Discovering Asteroids (Photo by Hubble Space Telescope)

26. What is the likelihood of an asteroid striking Earth? 628 Earth-crossing asteroids have the potential. Near misses: 1972 – space debris observed to skip off Earth’s atm. 1994 – 30 foot asteroid came within 65,000 miles 2002 – 2 passed within 233,000 miles & 75,000 miles respectively

27. Meteoroids, Meteors, & Meteorites Meteoroid – small rocky fragments in space Meteors – meteoroid that enter Earth’s atmosphere Meteorites – meteors that strike Earth’s surface

29. Meteor Showers Meteor frequency is generally more than 4 per hour. Most are result of Earth passing through debris from comet Annual occurrence

31. Types of Meteorites Stony Meteorites Iron Meteorites Stony-Iron Meteorites

32. Stony Meteorite

34. Iron Meteorite

36. Stony-Iron Meteorite