Astronomy Second-Third Test Flashcards
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.
elongation/conjunctions
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.
opposition
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
viking mars rover
first landing 1976, two vikings. original landing spot was too bouldery so they changed it mid-flight. landed with retrorockets and parachute. had a telescoping arm to reach for the soil, cleaning arms, cleaning arm whacked other arm. vaporized scooped stuff up.
sojourner+pathfinder
- rover+lander. with airbags. rover was a foot long.
spirit + opportunity
- twin rovers detected hematites. landed with parachute, airbags, platform. “blueberries”, sign of standing water previously on mars. martain surface (in one place) very fine packed sand (hard), dust devils.
oppy encountered
Cape victoria, old crater with eroded sides and sand dunes in the middle. Side features called duck bay and cape verde.
spirit found
on mesa called HOME PLATE. in polar region so during winter hibernated on slope for solar power. was almost lost during a monthlong sandstorm.
CURIOSITY
landed 2012. Heatshield->parachute->retrorockets->sky crane dropped it. found some organic molecules.
moons of mars.
phobos (28km) and deimos (16km). captured asteroids, not rounded. synchronous rotation.
jupiter four moons
Galilean moons, the four biggest. on a plane.
Jupiter outer atmosphere.
great red spot been spinning for hunderds of years- no friction below it to slow it down. different colored cloud bands paralell to equator. rotation period 9h50m. 11x diamter of earth, 300x mass. smaller storms caused by atmosphere turbulence, sweeps away ice crystals so you can see below surface.
layers going in
water ice->ammonium+ammonium hydrosulfate clouds->gradual transition to liquid (H2)-> liquid metallic hydrogen (H)->rocky core, size of earth.
transitions hard to deescribe, between liquid and gaseous, not discrete phases like on earth.
other jup facts
rings are solid particles (methane, water, Co2 ices) orbiting planet, aurorae caused by solar wind+atmosphere+jup’s magnetic field.)
MOON SIZES
ganymede, callisto, europa, io SIZES IN ORDER
Io
2% bigger than earth’s moon. Extremely volcanis as discovered by Linda Morabito at JPL in 79. Volcanos due to extreme tidal forces from Jupiter’s gravity. No atmosphere so volcanic material flies up, freezes, snows back down.
Europa
Like most jovian moons, ice-covered. ice-cover is a good insulator, liquid water possible below surface- LIFE POSSIBLe
Saturn facts
Rings made up of many ice chunks, shepard moons keep them around. Saturn tilt 27° means over 30 yr cycle that rings are seen from different angles to earth. has bands etc same as jupiter.
Titan
> 4% larger than mercury. Has an atmosphere 3x thicker than Earth’s, made of nitrogen and methane. Lakes and rivers of liquid methane on the surface. Boulders and chunks of methane. very cold though due to extreme distance from sun
Enceladus
Moon of saturn. covered with ice, which maintains a record of cratering throughout solar system history. tiger stripes near south pole spew liquid water as geysers- weird! Some kind of internal heating??
Uranus
has rings and moons. blue due to methane in atmosphere. white spots turbulence/storms. otherwise same as jupiter…
Neptune
bluer than uranus more methane. has a great blue spot. Predicted by perturbations in uranus orbit. Tilted 88°/92°. On side.
Triton
Moon of neptune. NOT titan. 80% size of earth’s moon. water ice, dirty water ice. retrograde rotation! WHY! IDK
Pluto.
Wrongly predicted 1915, discovered 1930 by Clyde Tombaugh found it.
How to discover pluto
Look at negative of star plates. apparent motion of stars, look for different ones. Really used BLINKER PLATE, shows 2 plates flashing make it easier to see differences. 10000s of stars, hard to see/find.
Charon
Moon of pluto- discovered from a silver lump in the photos 1978. Now 5 bodies, Nix and Hydro plus P4 and P5.
Pluto facts
VERY eccentric orbits compared to rest of solar system. on an incline too…. very cold, this atmosphere. dark and light areas can be mapped. eccentric enough that it crosses neptune’s orbit. terrestrial. Not a former moon of neptune.
eris and sedna
way out from pluto. nonsensical eccentric orbits.
planetary definition process
Harvard had definitions, E europeans had defintions. waited til last day of planet conference in prague when only E europeans were left- they voted one of theirs.
Shitty defition of planet
- Must orbit sun - exoplanet
- Must be massive enough to get spherical shape - minor planet
- Must have cleared its orbital path of debris - dwarf planet
Asteroids
Space rocks… asteroid belt. trojans following jupiter and in front of it. Apollo asteroids go from belt to earth around sun. earth people want to be able to divert the, >9000 near earth asteroids, possibly millions more.`
Comets
Ice bodies from outside solar system. can have absolutely gratuitous orbits. 1.5yrs to 17k years. Come in from any plane cause their origin is in a spherical shape around solar system.
Comet diagram/info
Water sublimates when it gets close to sun. Nucleus of comet (10km) across. Coma of the cost (glowing gas around head) 100,000km across. 2 tails. Ion trail always pointing away from sun, dust trail following orbital path. Often can break up close to sun, can spectrally analyze them!
