3. Touring Our Solar System
Chapter 23

4. 23.1 The Solar System
99.85% of the mass of our solar system is in the Sun, planets make up the rest.
Gravity holds planets in orbit.
Overview of the Planets
Terrestrial planets: small and rocky
Jovian planets: huge gas giants

5. How long is Jupiter’s “year”?
How long is Mercury’s “year?

6. 23.1 The Solar System
Interiors of the Planets Classes: (based on melting point) gases: H and He (-273oC) rocks: silicate and iron (> 700oC) ices: ammonia, methane, carbon dioxide, and water. (between others)

7. 23.1 The Solar System
Atmosphere of the Planets Planets can only have an atmosphere if gravity is great enough. Ex: Earth: 11 km/s escape velocity. He and H escape from Earth.

8. 23.1 The Solar System
B. Formation of solar System. Nebular Theory Sun and planets formed from a rotating disk of gas and dust. Planetesimals collided and built the planets and become round.

9. 23.2 Terrestrial Planets Mercury: Smallest planet (no atmosphere)
Dense with many craters
Scraps from cooling
Temperature:-173 to 427oC
59 earth-day rotation
88 earth-day revolution

10. 23.2 Terrestrial Planets Venus: 255 Earth-day “year”
Thick crushing atmosphere (97% carbon dioxide) 90x pressure Temperture-475oC
Radar maps shows basaltic volcanism and tectonic activity.
Most flat plains with few mountains.

11. 23.2 Terrestrial Planets Mars: Polar caps made of CO2
Large long dust storms
Most atmosphere escaped
Olympus Mons- 23 km high
Valles Marineris

12. 23.2 Terrestrial Planets Mars:
Rovers discovered marks of liquid water on Mars

13. 23.3 Outer Planets (and Pluto)
Jupiter: Giant Among Planets 1/800 of Sun Mass 2.5x greater then all others planets together. Great Red Spot- seen cyclonic storm seen Giovanni Cassini about Structure: pressure to make hydrogen into a liquid. May have rocky core.

14. 23.3 Outer Planets (and Pluto)
Jupiter: Moons: Io- volcanic Eurpoa- fractured icy surface Ganymede- largest, parallel groves Callisto- many craters

15. 23.3 Outer Planets (and Pluto)
Jupiter: Rings: Very faint Maybe fragments of 2 smaller moons

16. 23.3 Outer Planets (and Pluto)
Saturn: Rings: Main feature 100 m thick

17. 23.3 Outer Planets (and Pluto)
Saturn: Moons: 56 currently Titan – largest Atmosphere and hydrocarbon seas Enceladus-volcanic and water geysers

18. 23.3 Outer Planets (and Pluto)
Uranus: Planet on its side. Winking star was a sign of a ring (9) Miranda

19. 23.3 Outer Planets (and Pluto)
Neptune: Windy Planet 1000km/hr Great Dark Spot: Storm like Giant red Spot. Vanished! Repapered. Methane clouds. Triton –retrograde and volcanic

20. 23.3 Outer Planets (and Pluto)
Pluto: Dwarf Planet Fails to attract object in its orbit. (clearing its orbit) 228 years Charon-moon

21. 23.4 Minor Members
NEAR Shoemaker Landed on asteroid Eros Very low gravity Most asteroids are between Mars and Jupiter.

22. 23.4 Minor Members
Comets Made of rocks, frozen water, methane, carbon dioxide and carbon monoxide. Very elongated orbits. Tail points away from the sun.

23. 23.4 Minor Members
Comets Many short period come from the Kuiper Belt Long period come from the Oort Cloud

24. 23.4 Minor Members
Comets Halley’s Comet 1986 Giotto probe passed within 600 km 8 km x 16 km

25. 23.4 Minor Members
Meteoroids Small solid particles 3 sources: interplanetary debris asteroid belt comet remains Meteors-burn up in contact with atmosphere. Meteorites- reaches Earth

26. 23.4 Minor Members
Meteoroids Age of meteorites are about billion years old. Made mostly of iron. Meteor Showers- annual event from comet passes across Earth’s orbit.