1. Chapter 20: Our Solar System

2. Inner Planets Inner Planets often called Terrestrial Planets Rock Planets – Mercury – Venus – Earth – Mars Asteroid Belt separates inner and outer planets

3. Outer Planets Outer Planets known as Gas Giants or Jovian – Jovian means “Jupiter like” Have rings Comprised mainly of Gases – Jupiter – Saturn – Uranus – Neptune

4. Mercury

5. Smallest terrestrial planet and closest to Sun Mercury day = 59 Earth days Mercury year = 88 Earth Days Surface marked by craters Planet of extremes – Day = 700 K – Night = 100 K or -170°C

6. Venus

7. Density and internal structure similar to Earth – Often called “Earth’s Twin” – Also known as the Morning and Evening Star Venus day = 243 Earth Days Venus year = 225 Earth Days Hottest surface of any planet = 740 K – Accelerated greenhouse effect, dense atmosphere Sun rises in West and sets in the East

8. Mars

9. 4 th planet and last of the inner Mars day = 24.6 Earth Hours Mars year = 1.88 Earth Years Has Polar Ice caps Axis tilt allows for seasons Contains two Moons – Phobos and Deimos

10. Jupiter

11. Largest and Most Massive Planet Jupiter Day = 9.93 Earth hours Jupiter year = 11.9 Earth years The “Great Red Spot”, storm within atmosphere Strongest surface gravity of planets Io, Europa, Callisto and Ganymede discovered by Gallileo – Io volcanically active – Europa has icy crust hiding liquid

12. Saturn

13. 2 nd largest planet Saturn day = 10.6 Earth hours Saturn year = 29.4 Earth years Has most spectacular rings of any planet Moon Titan is larger than Mercury

14. Uranus

15. Uranus rotates top to bottom – Thought to have been struck by an asteroid Uranus day = 17.2 Earth hours Uranus year = 83.8 Earth years Discovered in 1781 by William Herschel

16. Neptune

17. Similar is size and shape to Uranus Neptune day = 16.1 Earth hours Neptune year = 164 Earth years Cold, blue planet containing visible clouds – Scientists think Neptune is shrinking, causing energy to be released into atmosphere creating storms Moon triton orbits Neptune backwards – Contains erupting geysers

18. Pluto

19. Pluto and Dwarf Planets Furthest “Planet” from sun Pluto day = 6.39 Earth days Pluto year = 248 Earth years Made mainly of “Ices” Orbits closer to the Sun than Neptune for 20 years Rotates with its moon Charon Considered a Kuiper Belt object