Dr. Henry Throop / University of Colorado 27-Jun-00 Astronomy 1110 Exam Review - Exam #2 The Jovian Planet Systems, Small Bodies, and the Formation of the Solar System ------------------------------------------------------------------------------ General info: The format of the exam will be roughly similar to the Exam #1, with a combination of multiple-choice, short answer, and essay questions. You'll have 95 minutes. Bring a calculator; all equations and units you'll need will be supplied. The exam will emphasize material covered in the last two weeks, but will also build on some knowledge you have from the first half of the course. Jovian Planets -------------- Gaseous Large -- 1000x volume of Earth! Saturn floats Huge atmospheres of Hydrogen, Helium, Methane Formation history Jupiter/Saturn: Largest Uranus/Neptune: Slightly smaller. Blue caused by methane All of them are warm: heat sources from differentiation & gravitational collapse Fusion: not in Jovian planets; requires higher pressures. Brown Dwarfs: halfway in between Jovian planets & stars Magnetic fields Jovian Satellites ----------------- Io, Europa, Ganymede, Callisto In some way like mini Solar Nebula; in some ways not Each is their own little world Lots of volcanism, tectonics, etc. even though far from Sun Additional source of heat keeps them warm! Tidal heating, integer ratio between orbital times of Io/Europa/Ganymede Tides squish satellites, heating them by friction and warming cores Io: no impact craters at all! Europa: ice `rafts' moving across surface. It was all liquid v. recently. Ganymede: Grooves on surface like Europa; bit older surface Callisto: heavily cratered; looks old; not much going on Satellites of Saturn: mostly ice & rock, except for Titan (methane atmo) Satellites of Uranus: Lots of tiny ones. Miranda = fractured by impactor Satellites of Neptune: lots. Triton has ice volcanoes Rings ----- Caused by collisions between broken up satellites, comets, etc. Icy Short-lived: millions (not billions) of years? Sometimes torn apart gravitationally, esp. near planet Saturn has big ring system now, but all of them may at some point in past or future Rings: close to planet Satellites: mostly further out Small Bodies ------------ Asteroids `Sawdust' left over after planets formed Couldn't form a planet because resonances with Jupiter pulled them apart Mostly confied to asteroid belt Occasional gravitational interactions will send them out of belt Continual grinding produces dust (like planetary rings!) Comets Similar to asteroids, but further out and icy Formation scenarios Formation of Solar System ------------------------- Main idea: look at all the large-scale characterics of our SS and find a model that works Collapse of Solar Nebula Composition at each distance is determined by temperature of nebula Density decreases outward in solar system, because condensation temperature for metals is high, and ices is low. Frost line Formation of terrestrial planets by accretion Formation of Earth-Moon system Formation of Jovian planets by accretion and then gas sweep-up Formation of other extra-solar systems Other models for solar system formation -- why or why not? Collisions ---------- Sometimes orbits are not predictable Bodies can be captured: change from orbiting sun to orbiting Jupiter, for instance Formation of Earth-Moon system Collision of Shoemaker-Levy/9 comet with Jupiter, 1994 Method of Science ----------------- Look at the data Publish (peer-review for technical accuracy) Look harder, broader Get more data Revise conclusions Repeat NASA funding ------------ Big & small missions Long-term planning Current Events -------------- Evidence for liquid water on Mars Extrasolar planet Life in our solar system, or elsewhere