Topic 5: Ken Nealson, Imre Friedmann Topic 6: Peter Ward and Donald Brownlee Bennett Ch. 9 &10 Goldsmith and Owen Ch Suggested reading for next HW assignment:

A brief tour of the solar system

Mercury Planet closest to the Sun Heavily cratered, no moons, no atmosphere, has iron core 0.38 the diameter of the Earth Surface temperature ranges from K (mean=452 K) Relatively strong magnetic field (still 1% of Earth’s) MESSENGER

Venus Sometimes called Earth’s “Sister planet” because similar in size. Atmosphere is primarily CO2 with small amount of Nitrogen 930 °F temperature Runaway Greenhouse effect Retrograde rotation 80% of surface is basaltic rock (lava), many volcanoes observed. Tectonics We have a 100m resolution radar map of the surface. Craters but not many larger craters or very small craters (WHY?)

Image from Venera 13

Mars Thin CO 2 atmosphere -60 C average surface temp Very arid with no organic molecules Huge, dormant volcanoes Evidence of past water. Surface made mostly of volcanic rocks 2 Moons: Phobos and Deimos

Map of Mars

Jupiter Largest planet in the solar system  mass= 318 Earths, volume=1200 Earths Brown Dwarf or “failed star” Mostly Hydrogen and Helium atmosphere Powerful magnetic field and gravitational force

Jupiter’s Inner moons

Europa

Tidal heating

Saturn Mostly Hydrogen and Helium The rings are either left over chunks of colliding moons or else left over “construction material” that never made it to becoming a moon.

Cassini-Huygens

Titan Only moon in solar system to have a dense atmosphere. There are ORGANIC molecules in the atmosphere An atmosphere of mostly Nitrogen with Methane Surface temp = -178 C Cryovolcanism?

Uranus and Neptune H, He, CH4 atmospheres Uranus: Lacks internal heat & so nearly featureless Axis is tilted by 90º, giving extreme seasons. Neptune: Has internal heat & an active atmosphere Has methane-rich haze which strongly absorbs red & orange light, letting blue & green light pass through.

Pluto Really a trapped Kuiper-belt object (smaller than our Moon) Kuiper-belt (50 AU out) consists of icy planetesimals: Not all of the outer solar-system material was consumed when the gas giants formed Has one moon: Charon

Comets Characterized by long period, heliocentric orbits Gases released include OH, CH, NH Nucleus of silicates and ice