Solar The System Overview ASTR 121 Sarazin
Saturn
Contents of the Solar System
Sun Planets Minor Planets (Pluto, asteroids, KBO's, etc) Satellites (moons) Comets Small stuff (< 100-m): meteoroids, gas, dust
The Planets
Sizes to scale, distances not to scale
Dwarf Planets and Asteroids
Asteroid Ceres
Asteroids
Asteroids Ida and Dactyl ("moon" of Ida)
Dwarf Planets
Pluto and Charon
Many other icy objects of similar size in outer Solar System
Eris
Comets
Comet Hale-Bopp
Kuiper Belt and Oort Cloud Realms of Ice
Meteors
Leonid Meteor Shower
Meteorites
The Planets
Sizes to scale, distances not to scale
Planets Increasing Distance from Sun
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune (Pluto)
Memorize!
The Solar System
Properties of the Planets
Distance (AU) Mercury 0.39 Venus 0.72 Earth 1.0 Mars 1.52 Jupiter 5.20 Saturn 9.54 Uranus 19.18 Neptune 30.06 Name Period Diameter Mass Density (years) (Earth=1) (Earth=1) 88 days 0.38 0.055 5.4 224 days 0.95 0.82 5.3 1.0 1.0 1.0 5.5 1.88 0.53 0.11 3.9 11.86 11.2 317.8 1.3 29.46 9.4 94.3 0.7 84.07 4.0 14.6 1.2 164.8 3.88 17.2 1.6
Orbits
Regularities in Planetary Orbits
Planets orbit nearly in a plane Planets revolve in same direction (counter-clockwise from north) Planet orbits nearly circular Systematically increasing spacing ("Bode's Law")
More Regularities
Plane of planetary orbits nearly equator of Sun Sun rotates in same direction that planets revolve Most planets rotate in same direction that they revolve (orbit, counterclockwise from north)
Clues to planet formation
Bode's Law?
Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune (Pluto) 4 4 4 4 4 4 4 4 4 4 4 3 & double Sum/10 0 0.4 3 0.7 6 1.0 12 1.6 24 2.8 48 5.2 96 10.0 192 19.6 384 38.8 768 77.2 a (AU) 0.39 0.72 1.00 1.52 5.20 9.54 19.2 30.1 39.4
Bode's Law?
Planet Mercury Venus Earth Mars Asteroids Jupiter Saturn Uranus Neptune (Pluto) 4 4 4 4 4 4 4 4 4 4 4 3 & double Sum/10 0 0.4 3 0.7 6 1.0 12 1.6 24 2.8 48 5.2 96 10.0 192 19.6 384 38.8 768 77.2 a (AU) 0.39 0.72 1.00 1.52 2.8 Ceres 5.20 9.54 19.2 30.1 39.4
Terrestrial vs. Jovian Planets
Terrestrial planets:
Mercury, Venus, Earth, Mars
Jovian planets:
Jupiter, Saturn, Uranus, Neptune
The Terrestrial Planets
The Jovian Planets
The Jovian Planets and the Sun
The Jovian Planets and Earth
Mars
Jupiter with Two Satellites
Terrestrial Planet Cross-Sections
Jovian Planet Cross-Sections
Terrestrial vs. Jovian Planets
Property Location Size Mass Density Surface Composition Terrestrial inner small small large solid, rocky Si, O, Mg, Fe Jovian outer large large small gas/liquid He
Terrestrial H, vs. Jovian Planets
Masses: Terrestrial: 0.06 to 1 MEarth Jovian: 15 to 320 MEarth
Density Terrestrial: 3.9 to 4.5 gm/cc Jovian: 0.7 to 1.7 gm/cc
Jovians gave strong gravity. Weight of 150 lb person on Jupiter = 400 lb. Escape velocity high
Saturn would float on water
Terrestrial vs. Jovian Planets
Rotation
Jovians rotate faster Terrestrial: Prot = 1 to 244 days Jovian: 10 to 15 hours
Oblate shape
Jupiter
Terrestrial vs. Jovian Planets
Rotation
Jovians rotate faster Terrestrial: Prot = 1 to 244 days Jovian: 10 to 15 hours
Satellites (moons) Terrestrial: few Jovian: lots
Jupiter with Two Satellites
Terrestrial vs. Jovian Planets
Rotation
Jovians rotate faster Terrestrial: Prot = 1 to 244 days Jovian: 10 to 15 hours
Satellites (moons) Terrestrial: few Jovian: lots Rings Terrestrial: no Jovian: yes
Saturn
Satellites (moons)
Big, round ones
7 with radii > 1000 km Ganymede, Titan bigger than Mercury
Lots of small irregular ones
"Planets" vs. "Satellites"
"Planets" vs. "Satellites"
S S P S
S
S
S
S
P
S
Satellites (moons)
Phobos
Light from Planets
Spectrum of Earth visible light = reflected sunlight infrared light = thermal radiation
Light from Planets
Thermal Radiation
Temperatures of planets 60-750 K Wien's law: max = 0.3/T cm = 3 x 106 / T nm = 4000 50000 nm
Thermal radiation from planets is infrared
Can use thermal infrared radiation to measure temperatures of planets
Light from Planets
Reflected sunlight
Visible light from planets is reflected sunlight Al...