1. Jupiter and Saturn Chapter 24

2. Jupiter Jupiter is the most massive of the Jovian (outer) planets It contains nearly ¾ of all the planetary matter in our solar system Jupiter has 64 objects that are orbiting around it at different times – 49/50 are officially moons, while the other 14/15 are unofficially (provisional) considered moons http://www.gearthblog.com/blog/archives/2006/04/google_jupiter.html

3. Surveying Jupiter Jupiter’s diameter is 11 times Earth’s and its mass is 318 times that of Earth’s It is composed mostly of hydrogen and helium with traces of methane, ammonia, and water Jupiter is slightly flattened – it is 6.37% larger in diameter, through its equator, than it is through its poles Jupiter emits twice as much energy as it receives from the sun

4. Jupiter’s Atmosphere Jupiter’s atmosphere is not deep – Information from the Galileo space probe and computer models come up with an atmosphere about 1,000 km in thickness That number seems high, but when we look at Jupiter’s diameter of 72,000 km it makes up only about 1% of its radius – in comparison Earth’s atmosphere is about 2.5% of its radius

5. Jupiter’s Atmosphere The clouds of Jupiter and organized into dark belts and bright zones – Zones appear to be high-pressure regions of rising gas that cool as it rises and forms clouds higher in the atmosphere where they receive more sunlight and look brighter – Belts are low-pressure regions with sinking gas and lower clouds that are not as brightly lit These two work together to create the circulation in the atmosphere

6. Jupiter’s Atmosphere Great Red Spot is a large circulation (similar to a hurricane on Earth) in the atmosphere of Jupiter that has been observed for over 330 years – It is twice the size of Earth http://hubblesite.org/gallery/album/pr1999029a/

7. Jupiter’s Ring Jupiter’s ring was discovered in 1979 by the Voyager 1 spacecraft – Very faint (dark) in comparison to Saturn’s rings because they are composed of mostly rock (silicate particles) instead of rock and ice like Saturn’s Roche limit is the minimum distance between a planet and a satellite that holds itself together by its own gravity – If a satellite’s orbit brings it within its planet’s Roche limit, tidal forces will pull the satellite apart

8. Comet Impact on Jupiter Shoemaker-Levy 9 was a comet that struck Jupiter in 1994 Hit Jupiter and released energy equivalent to a few million megatons of TNT – Bomb dropped on Hiroshima in WW2 was only about 0.15 megaton http://www.aem.umn.edu/people/faculty/shield/comet/comet.html

9. The History of Jupiter Jupiter formed from the colder gases of the outer solar nebula, where ices were able to condense It became massive enough to trap hydrogen and helium gas directly from the solar nebula The hydrogen takes the form of liquid metallic hydrogen, which is a very good electrical conductor The planet’s rapid rotation, coupled with the outward flow of heat from its interior, drives a dynamo effect that produces a powerful magnetic field

10. Jupiter’s Family of Moons Callisto: The Ancient Face – Outermost of Jupiter’s four large moons – Photographs from Voyager and Galileo spacecraft show that it has a dark and icy surface that is heavily cratered – It is believed through computer models that Callisto has a layer of liquid water roughly 10 km in thickness somewhere below its icy crust http://science.nasa.gov/science-news/science-at-nasa/1998/ast22oct98_2/

11. Jupiter’s Family of Moons Ganymede: A Hidden Past – It is larger than the moon and Mercury and over ¾ the diameter of Mars – It is the largest satellite in our solar system – Its surface shows presence of activity About a 1/3 of the surface is old, dark, and cratered the rest is marked by lighter parallel grooves – Current theories for groove formation suggest that tension in the crust stretched the landscape repeatedly to form the grooves http://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=11684

12. Jupiter’s Family of Moons Europa: A Hidden Ocean – Is smaller than Callisto and Ganymede, but has traces of water on its surface but that water seems to lie in an icy crust less than 100 km thick The long lines crossing the surface suggest a renewal process – They look like cracks in the ice crust where water from below has welled up and frozen – Europa is geologically active http://www.wired.co.uk/news/archive/2011-03/08/nasa-decadal-review

13. Jupiter’s Family of Moons Io: Bursting Energy – Inner most of the Galilean moons – Volcanism is continuous on Io It is heated by Jupiter and the volcanism is caused because of the strong tidal forces from Jupiter http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level2/io.html

14. The History of the Galilean Moons The minor moons of Jupiter are probably captured asteroids, but the Galilean moons more than likely formed in a disk-shaped nebula around Jupiter – a mini-solar nebula – We know that Jupiter was very hot when it formed, so, just like the terrestrial and Jovian planets formed in the solar nebula, the inner moons, Io and Europa, formed from rocky material, and the outer moons incorporated more ices

15. Planet Saturn Saturn is only about a 1/3 the mass of Jupiter and about 16% smaller in radius Saturn’s density is less than water – which means if we could put into a big enough container it would float in water http://en.wikipedia.org/wiki/File:Saturn_during_Equinox.jpg

16. Planet Saturn It radiates almost twice as much energy as it receives from the sun – It is hotter than astronomers thought it would be and they believe helium in the liquid hydrogen interior is condensing into droplets and falling inward and release energy as they pick up speed which heats the planet Saturn’s atmosphere is rich in hydrogen and contains the belt-zone circulation just like Jupiter – In comparison to Jupiter Saturn’s atmosphere is unremarkable (no visual storms or cloud formations)

17. Saturn’s Rings Saturn’s rings are made up of roughly 1000 ringlets no wider than 2 km The rings are composed of a combination of small rock particles and ice The rings more than likely were formed because a moon or icy planetesimal came too close to Saturn – Roche limit wouldn’t allow these objects to stay together and would have pulverized them into what we now see as rings Believed to have happened in last 100,000 years

18. The History of Saturn The planet formed in the outer solar nebula, where ice particles were stable It grew rapidly and became massive enough to capture hydrogen and helium Just like Jupiter many mysteries remain about this planet

19. Saturn’s Moons Most sources say that Saturn has 62 moons, most of them are small and dead – Just like Jupiter a most of these are captured asteroids or planetesimals http://saturn.jpl.nasa.gov/science/moons/

20. Titan Saturn’s largest satellite is a giant ice moon with a thick atmosphere and a mysterious surface The amazing thing about its atmosphere is that it has been able to hold on to it with its small size Been able to hold on to atmosphere because of its cold temperature – 95% nitrogen and 5% methane – Titan's brew of organic compounds is probably like the early Earth's chemistry. Its very cold temperatures may then have preserved a record of what the early Earth was like before life formed. Some info for Titan was copied from Nick Strobel's Astronomy Notes. Go to his site at www.astronomynotes.com for the updated and corrected versionNick Strobel's Astronomy Noteswww.astronomynotes.com