(Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) Terrestrial: Mercury, Venus, Earth, Marssmaller size & mass, high density, rock & metal, solid surface, few moons, no rings, closer to sun, closer together w/warmer surfaces. Jovian: Jupiter, Saturn, Uranus, Neptune. large size & mass, low density, H, He & H compounds, no solid surface, rings & many moons, farther from sun & father part, cool temp @ cloud tops. Asteroids: small rocky objects in asteroid belt between Mars & Jupiter. Ceres, Pallas, Juno → circular orbit, lie on asteroid belt. Apollo & Icarus → eccentric, carries inside orbit of earth. 3 asteroids larger than 400km in diameter. battered by impact cratering; “rubble piles”=evidence of multiple collisions. all asteroids combined = 150,000; <10% mass of the moon Trans-Neptunian objects: small objects orbiting beyond Neptune. Kuiper belt:contains small bodies of ice & rock, 30-50AU. Pluto=1st Kuiper belt object discovered; 900 today. Comets: small dirty ice objects coming close to sun, rock & mostly ice. when near sun, ice vaporizes & forms coma, cloud and durst around nucleus (ices of water, carbon, ammonia, dirty dust). Radiation pressure & charged particles emitted by the Sun (solar wind) push gas away from the comet & form the tail. tails: very tenuous gas escaping from coma, pushed by solar wind, dust tail is pushed by photons, only shown when near sun. short period (orderly, <200yrs) from Kuiper belt, 30-50 AU from sun. long period (random, >200 yrs) from Oort cloud, 50,000AU from sun; highly eccentric orbits. Meteoroids:bodies smaller than asteroids (<50m), stony/metallic debris, rocky or icy. Meteor (shooting star):meteoroid burning in the atmosphere. Meteor Showers (when Earth passes through the comets orbit) Earth crosses obit yrly, as comets dissipate, they leave debris behind that spreads out along their orbits, may not be uniform debris; localized clumps of debris = stronger meteor shower, small impacts happen almost daily,impacts large enough to cause mass extinctions are ms of yrs apart.Fireball:large meteoroid burning in the atmosphere. Meteorite:large meteoroid survives its fiery descent & reaches the ground. stony:95% of meteorite falls, rocky composition. irons:4% of meteorite falls, iron-nickel alloy.stony-irons:1% of meteorite falls, mixtures of iron-nickel alloy & rocky material. Uranus & Neptune: Mercury, Venus, Mars, Jupiter, Saturn known since ancient times. Uranus: was mistaken for star before being discovered; deviated from prediction by Newton’s gravity; one theory said it was because of the gravity of another planet →Neptune. Planet: A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape, & (c) has cleared the neighborhood around its orbit.dwarf planet:a,b, (c) has not cleared the neighborhood around its orbit, & (d) is not a satellite. Eris, Pluto, Ceres, Haumea, Makemake, Pluto. problemw/ new definition: some planets do not clear the neighborhood around their orbits.