Astronomy Exam II
Terms
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- Eclipse
- shadow of something on another object
- total eclipse
- completely in umbra
- partial eclipse
- partly in umbra/penumbra
- penumbra
- not clearly visible
- umbra
- total blockage
- lunar eclipse
- earth directly between moon and sun
- solar eclipse
- moon directly between earth and sun [new moon]
- annular
- ring of sun behind moon
- the ecliptic
- sun's path through the sky
- moon's path
- deviates 5 degrees from epliptic
- earth's crust
-
down 100 km
12 major plates - earth's mantle
-
goes about 1/2 way to center
solid but fluid - earth's core
-
liquid for about 2200 km
solid for about 1200 km - earth's inner core
-
solid from intense pressure
radio active fission keeps earth hot - earth's atmosphere overview
-
extends 100 km above earth
80% nitrogen
20% oxygen - earth's atmopshere progression
-
troposphere
stratosphere
ozone layer
mesosphere
thermosphere/ionosphere - troposphere
-
up to 11 - 20 km
[shrinks when far from sun
weather
heated by earth - stratosphere
-
up to 45 km
change in temperature
[cool --> warm] - ozone layer
-
up to 55 km
absorbs UV light
warmest region - thermosphere/ionosphere
- heat up because absorbs most stuff
- why are we warm on earth?
- more molecules hitting us create heat
- moon compared to earth
- 1/4 size; 1/100 mass; 1/6 gravity
- moon's maria
-
17% maria
- volcanic lava flows
- material much like earth's volcano
- younger than craters - moon's highlands
-
83% surface
mountains
craters - moon's soil
-
dust
glass particles [melted from impact]
found on highlands - moon's core
- not massive enough for solid IRON core
- moon's magnetic field
-
small magnetic field
PROBLEMATIC:
core should have cooled by now
NO liquid core
not as much fission creating heat
no atmosphere -
ORIGIN OF THE MOON:
double planet theory -
clump together masses
CHALLENGE:
different densities and compositions -
ORIGIN OF THE MOON:
fission -
lump of earth flies off
CHALLENGE:
different elemental abundances and wrong orbit -
ORIGIN OF THE MOON:
capture -
moon formed elsewhere & captured in our gravity
CHALLENGE:
very difficult to do w/o retrorockets -
ORIGIN OF THE MOON:
giant impact theory -
mars type object hits earth -> orbits
WORKS:
density difference
different elements
CHALLENGE:
what are chances of collision? - crazy moon stuff
-
- we should not have a moon that big
- wider on equators than poles
- tilt of earth would change in not so big - solar system
- anything on orbit around sun
- solar system's components
-
asteroid
comet
dust
moons
sun
planets - asteriods
- old, cratered, abnormally shaped
- comet
-
water, ice, carbon dioxide,
dirt, dust
10 km across - dust
-
100th size grain of sand
flying all over space
form planets - sun
-
100x bigger than earth
10x bigger than jupiter
99.8% of the solar system
[jupiter is more than 1/2 the rest] - planet sequence from sun
- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptrue, Pluto
- solar system lay out
-
- closer planets closer to sun
- orbit in a single plain [except pluto & mercury]
- counterclockwise orbits
- not very eccentric - terrestrial planets
-
mecury, venus, earth, mars
smaller, lower mass, high density
few or no satellites = fewer moons
no rings
slower rotation - jovian planets
-
jupiter saturn, uranus, neptune
bigger, more massive, low density
many satellites = many moons
all have rings
faster rotation - atmosphere and magnetic fields
- magnetic field has nothing to do with atmosphere
- mass and movement
- more massive things move slower at same speed
- jovian planet atmosphere
- hydrogen, helium, water, methane, ammonia, oxygen, nitrogen, carbon dioxide
- atmospheres' primary contents
-
primarily hydrogen and helium
enhances size -
ATMOSPHERIC FORMATION:
catasrophic theory -
two stars collide
similar to giant impact theory -
ATMOSPHERIC FORMATION:
evolutionary theory - rotating gas cloud become condensed by consercation of angular motion
- mercury
- 2nd smallest plante with pluto
- mercury's surface
-
craters similarly old, but less deep than moon
--more gravity so sides don't bulit so high
no maria, but SCARPS, fault lines - mercury's density
- lower density than earth, but more heavy elements [b/c of intense gravity]
- mercury's core and magnetic field
-
big nickel-iron core
magnetic field 1% of earth's
NO molten core - tidal lock
- simple rotio between rotation and revolution [same face always toward other object]
- mercury's rotation and revolution
-
tidally locked to the sun by gravity
rotates 1.5 times per revolution
1 revoltuion =.5 solar day; 2 yrs = 1 solar day - caloris basin
-
enormous crater impact [ripples]
sun's gravity locked onto area b/c densist
tidal pt. at closest to sun - atmosphere and temperature on mercury
-
large temperature variations
no atmosphere
ice on poles and in crators - if you were on mercury's surface
-
no atmosphere -- body pressure
10x influx of radiation
intense temperature
no oxygen b/c not atmosphere - venus
-
closest planet to earth
close to same size and density as earth - venus' magnetic field
- molten core [spinning] but NO magnetic field
- venus' rotation
- rotates backwards
- venus' surface
-
relatively flat
no wind
evidence of past volcanism & platetectonics
-similar to moon --yellow color b/c of sulfuric atmosphere - venus' atmosphere
-
96% carbon dioxide; 3.5% nitrogen
sulfuric acid clouds
200 mi/hr winds
surface pressure about 90x earth's -- much heavier
greenhouse effect - venus' greenhouse effect
-
temperature of 850F
gases trap heat
no liquid water to dissolve carbon dioxide [primary difference btwn venus and earth] - mars
-
1/2 size of earth
smaller denisty than earth - mars' rotation and orbit
-
large variation in distance from sun [25M mi] -- eccentric
just longer solar day
25 degree axis tilt WRT the elliptic -- seasonal - life on mars
-
- "plant life" theory
- canals -- channels on surface as if erroded by water
- bacteria -- meteorite from mars with fossilized bacteria - surface
-
valcanoes - olympus mons
valles marineris - olympus mons
-
15 miles high' bigger than WA
advantage of low gravity & no plates - valles marineris
-
deeper than grande canyon
as long as US is wide
not errosional - mars' atmosphere
-
95% carbon dioxide
no ozone to protect molecues
oxygen rusts iron in soil
1/200 atmosphereic perssure of earth
dust storms of very fine grains
denser in past - water flow
continuing to lose atmosphere
ice on poles -- h20 and co2 - mars' moons
-
phobos & deimos
less than 20 mi across
irregularly shaped
short periods [.3 & 1.3 days] - mars' magnetic field
- no magnetic core, but weak field