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3 planet properties

moons atmosphere type
Mercury: 0 trace terr
venus: 0 very thick terr
earth 1 perfect terr
mars 2 thin terr
jupiter 63+ very thick jovian
saturn 61+ very thick jovian
uranus 27+ very thick jovian
neptune 13+ very thick jovian
(pluto) 3/5 very thick jovian
rings around all four jovians, all on same plane going east around sun.


tilts of planets

.1° merc 177° venus 23° earth 25° mars 3° jupiter 27° saturn 98° uranus 30° neptune 120° pluto


smaller bodies in solar system

Ganymede is the biggest 5262km, then Titan, 5150km, then mercury, callisto, io, luna. Titan and Ganymede bigger than mercury!


Bode's Law

Not really a law and not really by bode.
Take the sequence 0,3,6,12... add four and divide by ten to get
.4, .7, 1.0, 1.6, 2.8, 5.2, 10.0.
This very nearly matches the distance of each planet from the Sun in AU going out in order.


Problems with Bode's law

at 2.8 there is no planet- asteroid belt instead, where jupiter's gravity prevented planet formation. Ceres' discovery in 1801 began to solve this problem.

Neptune does not fit in the pattern, pluto is where it should be. However pluto's orbit is so elliptical it sometimes is closer than neptune.


other thing to do with bode's law

get AU with bode, period/mass with newton's kepler's third.
Most massive moons of saturn also follow it.


Mercury facts

38% Earth's diameter
59d rotational period, orbit 88- 3/2 radio
every two revolutions of sun, hits apogee.
-315°F - 800°F ground temp.
.205 eccentricity
.01 albedo
trace atmosphere, 42% O2 (prolly Co2) 29% sodium, 28%H2
mag field 1% earth's.


Mercury surface

heavily cratered, rocky lava flows, extinct volcanos, bit of water ice.



For a body between an observer and the sun, the body will only get a certain number of degrees away from the sun in the night sky. This is when the planet's maximum distance from the sun as seen on its orbit's plane across the sun. East and west greatest elongations are these points, inferior conjunction is when planet is aligned between earth and sun, superior when planet is aligned on other side of sun.


Mercury's greatest elongation

28° as seen from earth, 15°/hr sky movement means less than two hours to see mercury. Mercury is small and faint, with one hour of dusk and any light polution it is very hard to see -fix this.


Messenger's path to mercury

did extremely intricate systems of oribts around earth, venus, and 3 times around mercury before it settled around there.


precession of merc's perihelion

will probably have to draw this, basically the orbit changes direction. early proof for general relativity.


mercury false color

yellows are basalts, craters are blue, looks like moon. RGB filters are combined on a computer.


Venus properties

82% earth's mass
surface temp 864°F
93x earth's temp
96% CO2, 3.5% nitrogen
no mag field
264 days retrograde rotation...


venus surface

sandy and rocky, extinct volcanos and lava fields, everything heavily eroded-all rocks flat. thanks to radar have detailed elevation map of venus. collapses pancake domes. maats mons 26k feet high. aranoids spidery formations.


venus atmosphere

a bit transparent to UV, transparent to radio, otherwise opaque. layer of sulfuric acid that rains down but doesn't get to surface. makes life difficult....


how to measure rotation

use radar/radio waves to measure doppler effect. First done in 1961 at the 85' dish at goldstone. Dish had transmitter to do bouncing. Rotation of side coming at you is blueshifted, away is redshifted.


why so slow rotation period

spin-orbit coupled with earth, same side faces us at each closest approach. mascons on venus!


why venus so hot

runaway greenhouse effect- heat from sun is trapped. on earth, IR heat radiates back into space. can't on venus. high temp causes outgassing from atmosphere causes more greenhosue etc etc. appears to be at equilibrium now. start of cycle unknown.


venus landers

soviet venera 13 and 14. soft landed on ring. had mass spec, camera, chonometer, color chart, soil drill, hydrometer. spectrometer too.


terraforming venus

transform C02 into o2. dump algae bombs on planet.


Mars facts

atmosphere 1/200th ours, mostly CO2.
24hrs 39 minutes day. - like us
25° tilt. - like us
-250-60°F night/day.


mars atmosphere

quite thin. mostly CO2. Water clouds, winds and sandstorms


mars surface

polar ice caps have H20 and CO2 frozen. frosts in floors of craters near poles. sand and rock, iron oxides, ice. evidence of past water flow everywhere, apparently liquid water still might be underground.


Olympus mons

extinct mountain volcano, 90k ft tall, 450 miles across. 3x height of everest.


Valles Marinaris

gigantic canyon, made from past liquid flow. as long as united states is wide.



close approach of two planets in orbit.


holes in mars surface

sometimes sides of extinct lava domes. 275 feet deep. tunnels- lava tube flows. maybe put astronauts in these caves?


evidence of past water flows

valles marinaris water flows, "wake islands" in old water channels, fault slip cliffs where water broke through and made a river.


current liquid water?

Normally water on mars is either frozen or vapor, not enough atmospheric pressure to have liquid. ice sublimates, but maybe pressure under surface allows for liquid. wet sand seen on wind-shaped cliffs