1. The Solar System (A Pitifully Brief Tour)

2. The Sun’s Family

3. Formed from a Solar Nebula 4.5Gyr ago Courtesy Penn State

4. Mercury 4 R o = 35 Mil. Miles 4 3000 miles in diameter 4 Lunar-like surface 4 Surface temp 800 o F 4 Yr = 88 days 4 Day = 59 Earth days 4 Large iron interior Ro is orbital radius

5. Venus 4 R o = 67 Mil. Miles 4 Close to Earth’s diameter 4 Shrouded in clouds 4 Temp 900 o F –Greenhouse effect 4 Yr = 243 days 4 Day = 248 Earth days –Retrograde rotation Radar image of surface

6. Mars 4 R o = 140 Mil. Miles 4 Half Earth’s diameter 4 Thin CO 2 atmosphere 4 Ave. Temp -81 o F 4 Two Moons, Phobos & Deimos 4 Yr = 2 Earth years 4 Day = 1 Earth Day

7. Jupiter 4 R o = 500 Mil. Miles 4 10.5 Earth Diameters –316 Earth’s to fill 4 -180 o F 4 Mostly gas –H, He, then some N 3, CO 2, CH 3 4 Zonal flows 4 63 Moons (as of 6/08) 4 Sparse rings 4 Yr = 11.9 Earth years 4 Day = 10 hours

8. Saturn 4 R o = 940 Mil. Miles 4 9.4 Earth’s in diameter 4 -218 o F 4 Mostly gas –H, He, then some N 3, CO 2, CH 3 4 60 Moons 4 Awesome rings 4 Yr = 29.6 Earth years 4 Day = 11 hours Two moons are visible

9. Rings-Roche Limit 4 The distance from a planet where the tidal forces on a moon can tear it apart, forming a ring

10. Rings-Collision 4 Rings can form when a moon is impacted by another moon, asteroid, or comet 4 Mimas (right) was hit by something that almost destroyed it

11. Rings-Contributions/Burglary 4 Some moons eject material into a ring system 4 Enceladus (right) contributes to Saturn’s rings with a ice geyser 4 Some planets scrap material off a moon

12. Uranus 4 Discovered in 1781 4 R o = 1.8 Bil. Miles 4 4 Earths in diameter 4 -323 o F 4 Mostly gas –H, He, some CH 3 4 Weak rings 4 27 Moons 4 Yr = 84 Earth years 4 Day = 17 hours

13. Neptune 4 Discovered in 1846 4 R o = 2.8 Bil. Miles 4 3.9 Earths in diameter 4 -323 o F 4 Mostly gas –H, He, some CH 3 4 Very weak wings 4 13 moons 4 Yr = 165 Earth years 4 Day = 16 hours

14. Pluto and the Ice Dwarfs 4 Discovered in 1930, demoted in 2006 4 New definition for planets: –Orbit the Sun –Spherical –Sweep out all material in their orbits 4 Ice dwarfs orbit in the Kuiper Belt 4 30-55 AU –1AU = 1 Earth orbital radius 4 -380 o F 4 Orbital periods of 250 years+

16. Asteroids 4 First (Ceres) discovered in 1801 4 30,000 named, perhaps 750,000+ 4 Most orbit in the Asteroid Belt, 2-5AU –NEOs cross Earth’s orbit 4 Most are oblong –Biggest are ~ 300 miles in diameter 4 Categories –Stony –Metallic –Carbonaceous Gaspra

17. Comets 4 “Dirty Snowballs” 4 Some come from Kuiper belt (short period), others from the Oort Cloud (long period) 4 Core ~ 10-25 miles in diameter 4 Coma ~ 100,000 miles in diameter 4 Tails ~ 1 Mil. Miles –Ion tail –Dust tail 4 Evaporate every time they come close to the Sun Comet West