Astronomy 161 -- Autumn 2009 (Prof. Stanek) Midterm 3 Study Guide (Friday, November 20) ------------------------------------------- Classes to review: The Earth Earth's Atmosphere The Moon Mercury Venus Mars Jupiter & Saturn Key Concepts: The Earth --------- (1) The study of seismic waves tells us about the Earth's interior. (2) The Earth is layered into crust, mantle, inner core, and outer core. (3) The Earth is layered because it underwent differentiation when molten. (4) The lithosphere is broken into plates that move relative to each other. (5) The motion of liquid metal in the outer core produces a magnetic field. Earth's Atmosphere ------------------ (1) The Earth's atmosphere consists mainly of nitrogen (N2) and oxygen (O2). (2) Without life, air would have no O2; without oceans, it would have more CO2. (3) The ozone (O3) layer has been partially destroyed by chlorofluorocarbons. (4) Excess CO2 can cause global warming via the greenhouse effect. The Moon -------- (1) The Moon's surface has both smooth maria and cratered highlands. (2) The surface was shaped by heavy bombardment, followed by lava floods. (3) The Moon has a thick crust but a tiny iron-rich core. (4) The Moon may have been ejected when a protoplanet struck the Earth. Mercury ------- (1) Mercury has a 3-to-2 spin-orbit coupling (not synchronous rotation). (2) Mercury has no permanent atmosphere because it is too hot. (3) Like the Moon, Mercury has cratered highlands and smooth plains. (4) Mercury has an extremely large iron-rich core. Venus ----- (1) The surface of Venus is hidden from us by clouds of sulfuric acid. (2) The atmosphere of Venus is hot because of a runaway greenhouse effect. (3) The surface of Venus shows volcanic activity but no plate tectonics. (4) The interior of Venus is similar to that of the Earth. Mars ---- (1) Mars has a tenuous atmosphere, with little water vapor and few clouds. (2) Mar has large volcanoes and a huge rift valley, but no plate tectonics. (3) Robotic "rovers" have given us a close-up look at Mars. (4) Mars has two small irregular moons, Phobos and Deimos. (5) Life on Mars?? Jupiter & Saturn ---------------- (1) Jupiter and Saturn consist mainly of hydrogen and helium. (2) Jupiter and Saturn have belts and zones of clouds, plus circular storms. (3) Jupiter and Saturn have magnetic fields created in metallic hydrogen. (4) Differences between Jupiter and Saturn are due to Jupiter's higher mass. (5) All Jovian planets have rings.