Astronomy Study: Seasons, Moon Phases, Eclipses, History, Orbits, Celestial Bodies, Study notes of Astronomy

Download Astronomy Study: Seasons, Moon Phases, Eclipses, History, Orbits, Celestial Bodies and more Study notes Astronomy in PDF only on Docsity! Your TA is cool and is doing your studying for you* Topics Ripe for Short Answer Questions  Seasons (there will be a question on this): N. Hemi. Summer N. Hemi. Winter -Sunlight concentrated (direct sunlight) -Sunlight spread out -Sun at higher altitude -Sun at lower altitude -Days are longer -Days are shorter -N. pole 24hr daylight -S. pole 24hr daylight **Be sure to indicate on your image that the earth is tilted 23.5 degrees!  Phases of the moon (there will be a question on this): - What causes it? Revolution of the Moon around the Earth causes the shadows of the Moon to be different at different times. - Earthshine: when sunlight bounces off the earth onto the dark part of the moon, illuminating the dark part of it (the light bounces back to Earth). NOTE: Only happens during crescent phases and it must be dark for you to see it! - Earthshine is not what causes the moon to look reddish during the eclipse! (homework question). What happens is refraction – when the earth’s atmosphere bends sunlight passing through. The atmosphere preferentially bends the red light, so the red light is bent more towards the moon and thus making the moon look reddish during a total eclipse (when it should be completely dark. - Memorize lunar phases (pink) sheet! Look at lab 2 and homework 2. - The phase of the moon is basically the SAME for everywhere on the Earth on a given day. - The astronaut on the moon sees the opposite phase (on the lunar diagram) on earth as the person on earth sees the moon. - Synchronous rotation – when an object rotates about its axis exactly ONCE per revolution around something (i.e. the Moon makes 1 rotation about its axis when it revolves around the Earth once).  Eclipses: - Umbra: part that is completely blocked. Penumbra: part that is partially blocked. - Solar Eclipse: moon in New phase. - An annular eclipse (think bull’s eye) happens when the moon’s umbra doesn’t touch the earth – sun is not completely covered. - You see a total eclipse if the moon’s umbra covers where you are on the earth. - You see a partial eclipse if the moon’s penumbra covers where you are on the earth. - Lunar Eclipse: moon in Full phase. Doesn’t happen very often because the moon orbits the earth on a 5 degree tilt, so it doesn’t line up correctly every time there’s a full moon. - The different types of lunar eclipses – same idea as described for solar, but switch the positions of earth and moon  Know your history: - Difference between geocentric (everything revolving around earth) and heliocentric (everything revolving around sun) theories.  Theory of Lunar Formation: - Giant Impact Theory: earth and body half its size formed near each other and began to differentiate. - Grazing collision about 4.5 billion years ago. - Knocked off earth’s mantle. - Other body’s core merged with earth’s core. - Loose material drawn by gravity formed the moon. - Observationally, see that moon is not as dense as core, supports previous point.  Greenhouse effect: - Visible sunlight penetrates atmosphere to surface. - Light is absorbed by the surface, then reemitted as infrared radiation (IR). - IR is absorbed and reemitted by the greenhouse gas. - IR does “random walk” through atmosphere – is basically trapped in the atmosphere and warms up the planet. Earth Moon Mercury Venus Atmosphere Yes No No permanent. YES! – Cloud covered, can’t see anything on the surface. Craters? Atmosphere erodes it, don’t see. Yes… lots of old ones, not much erosion. Heavily cratered surface. Magnetic Field Yes No – maybe in the past there was one. Weak magnetic field detected. No. Greenhouse Effect Keeps us warm! Main g. gas is water vapor. No. No. Runaway effect! Main g. gas is carbon dioxide. Density 5.5 g/cm^3 3.3 g/cm^3 5.2 g/cm^3 Misc Plate motion, iron core, surface features changes due to atmosphere. Not much happened since era of heavy bombardment. No changes since no atmosphere. Hard to observe – too close to the sun, transits, rapid warm up/cool down, not much going on. Crazy atmosphere, very high pressure at the surface b/c of the atmosphere! We bounce radar signals off Venus to make maps of the surface. See volcanoes, faults, craters (similar to earth). 1 day on Venus is 243 days on earth! Rotates slowly. Surface indicates geological activity. *Disclaimer* This is not intended to be everything you should study, just a summary of important (we think) topics that are likely short-answer questions. You should be studying other things as well, concentrating especially on the topics from the neon-colored review sheet. Also, by studying off of this sheet, you are implicitly agreeing to write “Mike/Lisa is the coolest TA EVER” on any part of the exam where these questions show up. You are also implicitly agreeing to not bitch if questions not on this sheet appear on the exam.