The Solar System (A Pitifully Brief Tour)

The Sun’s Family

Formed from a Solar Nebula 4.5Gyr ago Courtesy Penn State

Mercury 4 R o = 35 Mil. Miles 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

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

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

Jupiter 4 R o = 500 Mil. Miles Earth Diameters –316 Earth’s to fill 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

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

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

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

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

Uranus 4 Discovered in R o = 1.8 Bil. Miles 4 4 Earths in diameter 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

Neptune 4 Discovered in R o = 2.8 Bil. Miles Earths in diameter 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

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

Asteroids 4 First (Ceres) discovered in ,000 named, perhaps 750, 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

Comets 4 “Dirty Snowballs” 4 Some come from Kuiper belt (short period), others from the Oort Cloud (long period) 4 Core ~ 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