Astron notes - Google Docs PDF

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Here are the notes I took for chapter 11-13 they are pretty fire....

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Chapter 10: Venus and Mars. ➔ ➔ Venus ◆ .72 AU ◆ P = 225 ➔ Mars ◆ 1.52 AU ◆ P = 687 ➔ Because venus is in earth orbit we can see it either in evening in west after sunset or morning in the east before sunrise ➔ Because mars is outside we can see it anywhere on the ecliptic. ➔ Venus similar density to earth (5.2 g/cm) ◆ Similar radius ◆ temperature is alot higher ◆ pressure is alot higher ➔ Mars half earth size and lower density (3.9g/cm) ◆ colder than earth ◆ Thin atmosphere ➔ From earth venus is bright because it is close and also very reflected ◆ 17% of sunlight reflected ◆ This is because venus is covered in clouds ● Cant see surface with optical telescope ➔ From earth mars has a redish tinge due to iron oxides (rust) ◆ Regolith - soil on surface of mars ◆ We can see features and color variations/icecaps on mars ➔ Mars tilted at 25 degrees ◆ This allows it to have seasons similar to earth ◆ Day is 24 hours 37.5 mins ➔ Venus has a retrograde spin ◆ Cloud layre stoped us from determining rotation period until 1960s ● Radar was then bounced on planet to determined spin period ◆ Rotation period is 243 days (siderial day) ◆ Retrograde means looking above from the north pole it spins clockwise (earth spins counterclockwise) ◆ Venus year only 225 days ● Sun rises in west on venus when you put those motions together. ◆ Venus solar day only 117 days ◆ Retrograde spin theorized to be cause by large collision early in solar system ➔ Record time lander alive on venus 127 mins before it melted ➔ No erosion on venus ◆ Too hot for water or ice to exist so they cannot cause erosion ◆ Wind speed too low to cause erosion ➔ Volcanoes, impact craters and other features in crust ◆ No evidence for plat tectonics

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◆ Convection occurs in mantled ● Evidenced by stress features ○ Folds faults ridges and cracks ● No movement so no subduction zones. Much of surface consists of low lying lava planes like lunar mare ◆ Highlands: aphrodite and ishtar ● Both result of crust compression ● Maintained by mantle convection Many volcanoes ◆ Some evidence that they are active ◆ Some similar to our volcanoes ◆ Some have pancake dome-like structures Impactors ◆ 30km useful for dating Surface age: 300-600 million years (young!) ◆ Seems to have undergone planet wide resurfacing from some kind of volcanic convulsion Venus atmosphere ◆ Hot, dry, calm winds ◆ 96.5% CO2 ◆ 3.5% N2 ◆ 150ppm SO2 ◆ 20ppm H2O ◆ Pressure: 90 bars (equal to under 1km of water on earth) ◆ Sulphuric acid rain from clouds at top of atmosphere ◆ Troposphere at least 50km Phosphene found on venus ◆ Only know to be produced by life ◆ Could mean life on venus ◆ No explanation right now Surface temp ◆ 700+ kelvin ◆ due to runaway greenhouse effect ◆ Could have had oceans that evaporated due to sun releasing more energy Mars cold and dry ◆ May have once had water No sample return from mars ◆ We have samples from martian meteorites ◆ Rock ejected with lower escape velocity on mars due to less mass ◆ Samples contain gas bubbles, water, carbonbased compounds.

◆ Rocks have water and carbon based compounds in them suggesting presence of water and possibly life ➔ Mars overview ◆ Mostly silicate (low dense), small metal core ◆ Core thought to be solid because planet is smaller and we think it has had time to cool quicker than earth ◆ Supported by lack of global magnet field on mars ◆ Mars has local strong magnetic fields suggesting there was a strong magnetic field in the past ◆ Mars about half heavily cratered highland terrain mostly found in southern hemisphere ◆ Other half younger low lying volcanic plains in north ◆ Mars has lot of volcanoes ● Tharsis bulge is volcainic region ● On top is highest peak in solar system ○ Olympus mons: 20km high (3x taller than tallest earth mountain) ● Upswelling of tharsis bulge caused techtonic cracking of crust ○ Vallis marineris: massiv valley formed from cracking (not canyon because not cut by water) ○ Has experienced water erosion(earlier) and wind (still today) ◆ Surface ● Made of clay and iron oxides (reddish color) ● 35c to -143c ● Ice for h2o and co2 (dry ice) ● Atmosphere very thin ○...