Notes on Exam 1•We now have accumulated~35% of the gradedmaterial for the entiresemester•Exam 1: Mean and Medianis ~80%•Homework and quizsubmissions are decreasing– make sure to get thismaterial in!
DatesWeek #TopicReading/Notes1/7, 1/91History of Planetary ScienceCh. 4 & 51/14,1/162Tools of Planetary Science: Units, time,scientific method; Earth and Plate tectonicsCh. 61/23*3Earth and Plate tectonicsCh. 91/28, 1/304Earth’s MoonCh. 102/4, 2/65Mercury & VenusCh. 112/11, 2/136MarsCh. 112/18, 2/207Mars;Exam 1 (everything up to Mars)Ch. 122/25, 2/278Jupiter; SaturnCh. 123/4, 3/69Uranus & NeptuneCh. 143/18, 3/2010Pluton & CheronCh. 143/25, 3/2711Exam 2 (Jupiter to Pluto); TNOs: Asteroids,Comets, MeteoritesCh. 154/1, 4/312Formation of the Sun and Planetary SystemsCh. 164/8, 4/1013Extra Solar Planets & AstrobiologyCh. 274/15, 4/1714Mars missions: InSight and Mars 20204/2215Final Exam Week (exam time/location t.b.d.)*no class on 1/21 in observance of Dr. Martin Luther King Jr. Day
The Solar SystemTerrestrialPlanetsJovianPlanets
Recall: Jovian Planets•Large, gaseous, and low-density (“gas giants”)•Dominantly hydrogen and helium•All have moons that have characteristics similar to theinner terrestrial planets•All have rings of dust and ice particlesJupiterSaturnUranusNeptune
Jupiter: General Data•Period of Revolution:11.86 Earth years•Period of Rotation:9 hrs 56 mins•Axial Tilt:3.5°•Mass:1.9 x 1027kg (318 Earth masses)•Equatorial Diameter:139,822 km (~11 Earth diameter)•Distance from Sun:5.20 AU•Average Density:1.3 g/cm3(Earth is 5.52 g/cm3)•Albedo:44% (Earth is 30%)
Jupiter: History•Jupiter (and Saturn) have similar histories:•Both large enough to capture H and He from thesolar nebula because of their very large gravity•Ratio of H and He in Jupiter is similar to that in stars•Both most likely formed very soon after formation ofSun (as did other planets), as H and He would soonhave been swept into space by the solar windWe will talk about planetary formation later in thecourse
Jupiter: History•The very large size of Jupiter stronglyaffected surrounding space•Mars is likely so small becauseJupiter “grabbed” nearby material•Asteroids between Mars andJupiter weren’t able to form aplanet because of Jupiter’s largegravity (now called the AsteroidBelt)•Jupiter still acts as a “magnet” forasteroids•Probably saved Earth fromdestruction several times, but mayhave attracted some big rocks
Jupiter: General Data•Rotation:~10 hours (2.5 times faster than Earth)•Contributes to its shape being about 6% wider nearthe equator than from pole to pole (142,984 kmequatorial, 133,708 km polar)•Flattening due to rapid rate of spin and “fluidity” ofthe surface (mostly hydrogen gas)•Diameter:Jupiter is almost as large as a gas planet canbe•If more material were to be added, it would becompressed by gravity such that the overall radiuswould only slightly increase•A star can be larger only because of its internal(nuclear) heat source that acts against gravity