1. SOAR Fall 2004 Earth’s place in the cosmos

2. Population of the Cosmos ~100 Billion Galaxies = 10 11 Galaxies ~ 100 Billion Stars in each galaxy = (10 11 stars)(10 11 Galaxies) = 10 22 stars ~ 10 planets around each star = 10 23 planets … potentially lots of company, but it’s very far away! ~100 Billion Galaxies = 10 11 Galaxies ~ 100 Billion Stars in each galaxy = (10 11 stars)(10 11 Galaxies) = 10 22 stars ~ 10 planets around each star = 10 23 planets … potentially lots of company, but it’s very far away!

3. Earth-Moon Distance r EM = 250,000 miles Earth-Sun Distance 93,000,000 mi = 1 AU (372 r EM = 1 AU) Sun-  Centauri Dist. 4 ly = 4(63,200 AU) (1 ly = 6x10 12 mi) Milky Way Diameter R MW = 100,000 ly MW-Andromeda Dist. R and = 2,000,000 ly Farthest Galaxy R far = 11 Billion ly Earth-Moon Distance r EM = 250,000 miles Earth-Sun Distance 93,000,000 mi = 1 AU (372 r EM = 1 AU) Sun-  Centauri Dist. 4 ly = 4(63,200 AU) (1 ly = 6x10 12 mi) Milky Way Diameter R MW = 100,000 ly MW-Andromeda Dist. R and = 2,000,000 ly Farthest Galaxy R far = 11 Billion ly Scale of the Cosmos = 264,000,000,000,000,000,000 r EM

4. Motion of Earth Rotation on axis v Equator ~ 1000 mph, v Canton ~ 700 mph Orbit about Sol v Earth ~ 70,000 mph Orbit about center of Milky Way v Sun ~ 560,000 mph Milky Way in Local Group v MW ~ 280,000 mph Local Group falling toward Virgo Cluster v LG ~ 1,750,000 mph Rotation on axis v Equator ~ 1000 mph, v Canton ~ 700 mph Orbit about Sol v Earth ~ 70,000 mph Orbit about center of Milky Way v Sun ~ 560,000 mph Milky Way in Local Group v MW ~ 280,000 mph Local Group falling toward Virgo Cluster v LG ~ 1,750,000 mph

5. The Milky Way Galaxy ~ 300 Billion Stars, some with planets

6. The Milky Way Galaxy Sun ~ 30,000 ly from center Galactic Year ~225,000,000 yr (Sol is ~22) Sun ~ 30,000 ly from center Galactic Year ~225,000,000 yr (Sol is ~22) M87, a galaxy much like the Milky Way http://www.eso.org/outreach/press-rel/pr-1999/pr-18-99.html

7. Solar System Sun & Planets formed from interstellar clouds collapsing under gravity

8. Solar System Inner Worlds: Mercury, Venus, Earth, Mars Positions at 17:00 UT, 1/23/04 1 AU= 150,000,000 km = 93,000,000 mi

9. Solar System Outer Worlds: Jupiter, Saturn, Uranus, Neptune, Pluto Positions at 17:00 UT, 1/23/04 SS width~ 12,000,000,000 km ~ 7,500,000,000 mi