Survey of the Solar System

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John Rogers
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1 Survey of the Solar System The Sun Giant Planets Terrestrial Planets Minor Planets Satellite/Ring Systems EAS 4803/ CP 3:1

2 Mars update Endeavour crater, 6 Aug 2011 EAS 4803/ CP 3:2

3 Mars update Endurance crater, Nov 2004 EAS 4803/ CP 3:3

4 Mars update Endeavour crater rim, 16 Aug 2011 EAS 4803/ CP 3:4

5 Terrestrial Planets Mars Mass Radius Orbit Rotation EAS 4803/ CP ~ 6.4 x 1023 kg ~ 3390 km ~ 1.5 AU ~ 24.6 hrs Viking mosaic of Olympus Mons Slope flows on crater wall 3:5

6 Mars Dynamic surface, extreme geologic features Thin atmosphere (~7 mbar) Active weather/seasons 2 satellites Remnant magnetic field No rings Aurora History of water Terrestrial Planets Dust devil viewed by Spirit MRO: polar avalanche seen from orbit EAS 4803/ CP 3:6

7 Mars Terrestrial Planets Spirit dust devil movie EAS 4803/ CP 3:7

8 Survey of the Solar System The Sun Giant Planets Terrestrial Planets Minor Planets Satellite/Ring Systems EAS 4803/ CP 3:8

9 Pluto July 3, 2011 EAS 4803/ CP 3:9

10 What Happened to Pluto? A planet as defined in 2006 by the IAU (International Astronomical Union): 1. Orbits the sun 2. Is large enough to have become round due to the force of its own gravity 3. Is not a satellite 4. Must dominate the neighborhood around its orbit (cleared its orbital path) EAS 4803/ CP 3:10

11 What Happened to Pluto? Recognized planets Year EAS 4803/ CP 3:11

12 Definition of a dwarf planet 1. Orbits the sun 2. Is large enough to have become round due to the force of its own gravity 3. Is not a satellite 4. Must dominate the neighborhood around its orbit (cleared its orbital path) Currently there are 5 recognized by the IAU: Ceres, Pluto, Haumea, Eris and Makemake Though due to difficulties in confirming KBO roundness there are probably >100 known objects EAS 4803/ CP 3:12

13 Minor / Dwarf Planets Earth For Scale: (Ceres) Eris Ceres Pluto (& Charon) 102 probable, 390 possible x Image credit: M. Brown Image credit: NASA EAS 4803/ CP 3:13

14 Asteroids Minor planets with unconfirmed roundness and generally < 500 km in radius. Most reside in the asteroid belt between Mars and Jupiter s orbits. Other populations include centaurs, Trojans, Kuiper belt objects (e.g., Pluto). They actually can, and several do, have confirmed satellites. EAS 4803/ CP 3:14

15 Vesta July 24, 2011 EAS 4803/ CP 3:15

16 Asteroids and Comets Visited EAS 4803/ CP 3:16

17 Comets Ice-rich objects that lose mass in the form of water vapor and ice/dust grains when exposed to sufficient solar heating. Mostly reside in the Oort Cloud (1-5 x 10 4 AU) and Kuiper Belt region Hale-Bopp, 1997 EAS 4803/ CP 3:17

18 Comets: Revisiting Tempel 1 July 4, 2005 February 14, 2011 EAS 4803/ CP 3:18

19 Survey of the Solar System The Sun Giant Planets Terrestrial Planets Minor Planets Satellite/Ring Systems EAS 4803/ CP 3:19

20 Satellites All but two planets (Mercury & Venus) have satellites, as do several asteroids and minor planets The giant planets have tens of satellites each Have a broad spectrum of variability EAS 4803/ CP 3:20

21 Satellites Giant Planet Satellite Systems: Tens of moons Inner moons in prograde orbits about planet and close to the equatorial plane with low eccentricity Distant moons can orbit in any direction, at any inclination and with extreme eccentricity Photo by Jan Sandberg EAS 4803/ CP 3:21

22 Giant Planet Satellite Systems: Satellites Tidal forces due to orbital eccentricity and changing gravity from other moons can generate significant interior heat for moons EAS 4803/ CP 3:22

23 Giant Planet Satellite Systems: Satellites Tidal heat could potentially be translated to driving volcanic activity, heating a subsurface layer, etc. EAS 4803/ CP 3:23

24 Satellites Giant Planet Satellite Systems: Diffuse atmospheres have been detected at several moons, including: Io, Ganymede, Enceladus Titan s atmosphere is thicker than Earth s EAS 4803/ CP 3:24

25 Terrestrial Moons: Satellites Earth s moon thought to be from a large impactor early in the solar system s history Mars two moons appear to be captured asteroids likely from the nearby asteroid belt. Deimos & Phobos from MRO EAS 4803/ CP 3:25

26 Satellite Sizes Pluto and Earth have largest moons relative to their size; both are likely formed from the impact of secondary planetesimals Ganymede and Titan are larger than Mercury Smallest moons are ~ km in size Earth and Moon from Messenger spacecraft EAS 4803/ CP 3:26

27 Ring Systems Only giant planets have confirmed ring systems Generally thought to reside within a few radii of the planet (but recent observations show otherwise!) Characteristics are quite variable between systems, raising many questions with respect to ring formation, life expectancy, and evolution. EAS 4803/ CP 3:27

28 Saturn: Ring Systems Most observed and dynamic of the ring systems Ring particles are made nearly entirely of water ice, with some dust and other chemicals Sun eclipsed by Saturn from Cassini EAS 4803/ CP 3:28

29 Ring Systems Saturn: Rings dynamically shaped by moons causing waves, channels, gaps, etc. EAS 4803/ CP 3:29

30 Ring Systems Saturn: E Ring sourced from cryovolcanism on the moon Enceladus EAS 4803/ CP 3:30

31 Saturn: Latest ring discovery by Spitzer Space Telescope: ring orbiting at 100 R s and tilted 27º from inner ring plane Corresponds to orbit of irregular moon Phoebe Ring Systems EAS 4803/ CP 3:31

32 Solar System Formation in Brief EAS 4803/ CP 3:32

33 Solar System Formation: Constraints Sun has 99.8% of mass, <2% of angular momentum Low inclination & eccentricity of planet orbits Most planets have low obliquity Large outer planets have ~solar composition Small inner planets enriched in heavy elements Debris in asteroid belt, Kuiper belt Meteorites have common age: ~4.6 Ga Oldest Moon rocks ~ Ga EAS 4803/ CP 3:33

34 Solar System Formation in Brief Gravity leads to collapse of gas/dust cloud Initial net rotation à rotating disk Dust grains in disk collide, forming planetesimals Planetesimals collide and merge, forming planetary embryos Late collisions of embryos may have disproportionate influence Eventually, solar wind disperses unaccreted gas EAS 4803/ CP 3:34

35 Solar System Formation in Brief Inner planets built from only rock and metals Outer solar system forms cores of ices+rocks+metals Sufficiently large cores accrete gaseous H and He è Need to form these cores before the gas is blown away! EAS 4803/ CP 3:35

36 Solar System Formation in Brief These are some of the things that hydrogen atoms do given fifteen billion years of cosmic evolution. C. Sagan EAS 4803/ CP 3:36

37 Weekend Assignment The planets are shown with the correct relative sizes, and the correct relative orbital distances, though the sizes of the bodies are greatly exaggerated relative to the orbital distances. EAS 4803/ CP 3:37

Solar System Fact Sheet

Solar System Fact Sheet (Source: http://solarsystem.nasa.gov; http://solarviews.com) The Solar System Categories Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Rocky or Gas Rocky Rocky Rocky Rocky