1. Introduction to the Solar System The bright star Antares embedded in dust and gases

3. The Formation of the Solar System Our solar system began as a rotating gas cloud or nebula that collapsed toward its center under the influence of gravity. A condensation formed at the center, which is called a protostar. A flattened disk of matter surrounded the protostar, which begtan to shine and become a star, our sun.

8. Common Properties of Planet Orbits in Our Solar System As viewed from above, all of the planets orbit the Sun in a counterclockwise direction. The planets orbit in nearly the same plane (ecliptic). All planets except Pluto have an orbital inclination of less than 7°.

9. Inner Solar System http://www.nineplanets.org/overview.html

10. Outer Solar System http://www.nineplanets.org/overview.html

13. Ecliptic: Artist’s View

21. Diameters Planet Diameter (Earth = 1) Mercury 0.38 Venus 0.95 Earth 1.0 Mars 0.53 Jupiter 11.21 Saturn 9.45 Uranus 4.01 Neptune 3.88 Pluto 0.18

23. Masses Planet Mass (Earth = 1) Mercury 0.06 Venus 0.81 Earth 1.0 Mars 0.11 Jupiter 317.94 Saturn 95.18 Uranus 14.53 Neptune 17.14 Pluto 0.002

25. Average Density (kg/m 3 ) Planet Average Density (kg/m 3 ) Mercury 5430 Venus 5250 Earth 5520 Mars 3950 Jupiter 1330 Saturn 690 Uranus 1290 Neptune 1640 Pluto 2030

27. Rotational Period Planet Days (Earth  1) Mercury 58.6462 Venus 243.0187 Earth 0.99727 Mars 1.025957 Jupiter 0.41354 Saturn 0.42637 Uranus 0.71806 Neptune 0.67125 Pluto 6.3872

29. Average Temperature Planet Ave Temp ( ° F) Mercury 354 ° Venus 867 ° Earth 45 ° Mars -81 ° Jupiter -186 ° Saturn -202 ° Uranus -337 ° Neptune -364 ° Pluto -380 °

30. Average Temperature (Earth = 1)

32. Two Basic Groups of Planets TERRESTRIAL (earth-like) Small size, low Mass Higher density Mostly rock Mercury, Venus, Earth, Mars JOVIAN (Jupiter-like) Large size, massive Low density Mostly gas Jupiter, Saturn, Uranus, Neptune

38. Classification Table Planet Rocky or Gas? Small or Giant? Inner or Outer? Inferior or Superior? Classical or Modern? Mercury R S I I C Venus R S I I C Earth R S I N/A ? Mars R S I S C Jupiter G G O S C Saturn G G O S C Uranus G G O S M Neptune G G O S M Pluto ? S O S M