chapter 12 (pt. 1), 13 & 14 Flashcards
evidence for planet/star common origin comparative planetology of metallic/rock planets liquid-gas giant planets of the outer solar system
Earth
home, third rock from the Sun, water planet, thin atmosphere altered by life, large terrestrial
[mantle, plate tectonics, primary atmosphere, secondary atmosphere, greenhouse effect]
Moon
a planet-like companion to Earth made of the Earth’s ocean crust
[albedo, anorthosite, breccia, ejecta, maria, micrometeorite, large-impact hypothesis, magma ocean, multiringed basins, late heavy bombardment]
Mercury
a metal planet, cooling and shrinking against the cold of space, smallest planet in solar system
[fast, very dense, inactive]
Venus
initially a water planet, clouding over and heating which boiled off its water so its now dry
[runaway greenhouse effect, coronae]
Mars
small water planet unable to hold its atmosphere which boiled away water making a cold desert
[shield volcano, outflow channel, valley network, permafrost, moons]
Jupiter
massive, largest planet in solar system, ball of liquid metallic hydrogen, extensive moon system, sidereal rotation period 10 hours, spins the fastest of all planets
[oblate, liquid metallic hydrogen, magnetosphere, belt-zone circulation, forward scattering, Roche limit, tidal heating]
Saturn
massive, visibly bright ice-particle ring, ball of liquid metallic hydrogen, extensive moon system
[ring system, shepherd satellite, gap, Titan, liquid methane/ethane, Enceladus, tiger stripe]
Uranus
ice giant, rich in solid and liquid water, rotation inclined to ecliptic about 98º
[trace methane, occulation, moon with ovoids]
Neptune
ice giant, rich in solid and liquid water, rings NOT easily detactable from Earth, satellite system, 2 discovered from Earth, 6 by Voyager 2 (1989),
Great Dark Spot (dark blue) roughly the size of Earth, circulating hurricane
Plutino, Pluto
a dwarf planet (IAU defines ‘planet’ as gravitationally spherical, dominate orbit, bound to star)
[dwarf planet]
Terrestrial planets
Earth-like, small diameter, dense (of rock or metal), rocky, little or no atmosphere
[crater, asteroid, meteoroid (meteor, meteorite), meteor shower, carbonaceous chondrite, volatile, half-life]
Jovian Planets
“liquid” giants (compressed gas), worlds of the outer solar system (resemble Jupiter)
[comet, Kuiper Belt, Oort Cloud]
solar nebula theory
rotating cloud of gas/dust gravitationally collapse and flatten, around forming Sun disk rotates counter clockwise, all planets revolve in the same direction, rotate as well
[uncompressed density, ice line, condensation, condensation sequence, accretion, planetesimal, protoplanet, gravitational collapse, heat of formation, differentiation, outgassing, Late Heavy Bombardment, Near Earth Objects (NEO)]
evolutionary theory
phenomenon involving slow, steady, process of sort seen happening present day
catastrophic theory
phenomenon involving special, sudden, perhaps violent events
comparative planetology
comparison of one planet with another, Earth as the template
active core (Earth)
refers to geologically mobile, as heat stirs and makes its way out of the interior
mantle (Earth)
deep layer - Earth’s dense rock, properties of solid but capable of flowing slowly (like asphalt)
crust (Earth)
rocky low-density surface, radiates heat out into space
smooth surface is younger (lava flow) than cratered area (Late Heavy Bombardment)
plate tectonics (Earth)
crust plates floating on mantle (Greek for “builder”)
100s M.y. movement (0.1 G.y.) 1/45 age of Earth, so sections of crust in rapid motion
atmosphere (Earth)
larger size and cooler temperature of planet important to retaining gases
gases originate from formation, space deliveries, evolution of the planet, appearance of life
primary atmosphere (Earth)
planet’s first atmosphere, gases from solar system nebula (hydrogen, methane) outgassing of carbon dioxide, nitrogen, water vapour, etc., cooked-out of hot planet rock
accreting planetesimals rich volatile materials (water, ammonia, carbon dioxide, etc.)
secondary atmosphere (Earth)
replaces the primary atmosphere, e.g., outgassing, impactors, bioactivity
Earth’s relatively thin, mainly nitrogen, significant oxygen from biologucal processes
greenhouse effect (Earth)
carbon dioxide (CO2) rich atmosphere traps heat and raises planet surface temp. visible wavelength sunlight shines through glass roof of greenhouse, heats interior without greenhouse effect Earth would be 30ºC cooler, average temp. below freezing human action that add CO2, water, and gases, being researched for forcing of current climate
global warming (Earth)
gradual increase in surface temperature of Earth caused by human modifications, a concept no longer used by science which claims to link all climate change directly to human action
surface evolution (Earth)
report of changes that destroys traces of earlier formation processes
albedo (Moon)
ratio of the amount of light reflected from an object to the amount received
perfectly black = 0, perfectly white (full reflection) = 1
Moon albedo is not that high (0.06) only reflects about 6% of light that hits it, a dark grey world
anorthosite (Moon)
light coloured, aliminum and calcium-rich silicate rock, first solidified, float to top
most rock is hardened lava and breccia (fragments of older broken bound together)
maria (mare, Latin “seas) (Moon)
smooth lunar lowlands of successive flows of dark lava
micrometeorites (Moon)
meteorites of microscopic size
large impact hypothesis (Moon)
1970s, Moon formed when Mars size planetesimal smashed into Earth
magma ocean exterior (Moon)
newborn Moon, shell of molten rock hundreds of km thick
late heavy bombardment (Moon)
impacts from possible final accretion and migration of Uranus and Neptune
multiringed basin (Moon)
large impact feature, +/- 2 concentric rims, fracture of planet crust, 100skm diameter
fast (Mercury)
orbital period of 88 days
very dense (Mercury)
sugggests a large metallic core about 70% of planet radius (metal planet, thin rock mantle)
inactive (Mercury)
due to lost internal heat, core contracted, crust compressed and broke in long shrink ridges
runaway greenhouse effect (Venus)
greenhouse effect so dramatic it amplifies itself
hot (Venus)
the surface can melt lead
it is corrosive and has great pressure
no spacesuit is protective
coronae (Venus)
large round geological faults in the crust caused by intrusion of magma below the crust
iron oxide (Mars)
reddish orange mineral caused by oxidation of iron in the presence of free O2 molecules
outflow channels (Mars)
geological surface feature flow of vast amount of water released suddenly
valley networks (Mars)
system of drainage channels, resemble beds of rivers and tributary systems on Earth but some water may still be present at permafrost
permafrost (Mars)
permanently frozen soil that seasonally thaws
satellite system [moons] (Mars)
very tiny so cold, irregular (potato) in shape, likely captured asteroids
oblateness (Jupiter)
flattening of spherical body caused by rotation, fraction equatorial diameter exceeds polar
heavy element core (Jupiter)
“rocky core” refers to chemical composition (iron, nickel,silicon, …), NOT properties this matter 4x hotter than the surface of the Sun, pressure 50 million times Earth’s at sea level
liquid metallic hydrogen (Jupiter)
liquid hydrogen under very high pressure, good conductor electricity stirred by convection currents and spun by planet’s rapid rotation drives dynamo effect
magnetosphere (Jupiter)
magnetic field volume of space around planet, traps solar wind charged particles
aurora (Jupiter)
charged solar particles follow polar magnetic fields, imaged by UV for Jupiter
belt-zone circulation (Jupiter)
cloud belts and zones form stripes that circle the planet parallel to equator ammonia (NH3), ammonia hydrosulphide (NH4SH), water (H2O) can condense into droplets
belt - darker descending gas lower in atmosphere
zone - brighter, rising gas cloud high in atmosphere, reflects stronger sunlight near surface to viewer embedded circulating storms
forward scattering (Jupiter)
optical property, finely divided particles, direct light in direction light is traveling
diameters approximately equal to wavelength of visible light, cigarette smoke size within Roche limit
Roche limit (Jupiter)
minimum distance planet to a satellite that can hold itself together by own gravity
satellite within Roche limit is pulled apart by tidal forces (where raw material cannot coalesce)
about 2.4x the planets radius, depending somewhat on the relative densities of planet and moon
tidal heating (Jupiter)
heating of a planet or a satellite because of internal friction due to (gravitational) tides
satellite system (Jupiter)
4 large Galilean moons
related to eachother and probably formed with Jupiter
[Io, Europa]
Io
slightly larger than Earth’s moon (looks like a pizza)
density 3.6g/cm^3, rock and metal
intense warming (tidal heating) could have driven off much internal ice
Europa
slightly smaller than Earth’s moon (looks like cracked ice ball) density 3g/cm^3, mostly rock with thin ice crust, visible surface very clean, few craters, long cracks
- geologically active crust breaks as moon is flexed by gravitational tides from Jupiter and other moons
- liquid water ocean 20km deep suggested by the gravitational influence on Galileo spacecraft
ring system (Saturn)
multiple rings (e.g., Saturn's three main rings, A, B, C) golf ball size chunks of ice mainly, sometimes rock, down to dust from broken satellites and geysers
shepherd satallite (Saturn)
body that confine rings, gravitationally usher stray particles back into the rings
gap (Saturn)
space in rings that is not empty, small moon orbits inside
Titan (Saturn)
the largest moon of Saturn (bit larger than Mercury), surface fluid circulation system and erosion
liquid methane/ethane (Saturn)
hydrocarbon at very cold temperatures (180ºC)
Enceladus (Saturn)
moon of Saturn, signs of recent geological activity, some parts 1000 fewer craters
tiger stripe (Saturn)
tidal force fissure or crustal crack where liquid water erupts as geyser
trace methane (Uranus)
small quantity causes a teal, or green-blue, or green colour in planetary atmosphere
rings NOT easily detectable from Earth, dark, faint, contain little dust, confined by shepherd satellites
occulations (Uranus)
passage of a larger body in front of a smaller one, planet in front of a star
Miranda (Uranus)
innermost moon of the 5, 14% the diameter of Moon
Ovoid (Uranus)
surface marks groves, oval features may have been caused by internal heat, convection
dwarf planet (Pluto/Plutino)
body orbiting Sun, not satellite of planet, round but not massive enough to clear its orbit
Plutino
one of the icy Kuiper belt objects caught in a 3:2 orbital resonance with Neptune (like Pluto)
crater (Terrestrial planet)
impact size, nearly every firm surface in the solar system peppered by meteorite impacts
asteroids (Terrestrial planet)
small rocky world, most orbit the Sub between Mars and Jupiter in the Asteroid Belt
meteoroid (Terrestrial planet)
small bit of matter (dust, sand, pebble, most less than 1 gram) in space
meteor (Terrestrial planet)
meteoroid falling into Earth’s atmosphere, friction heats it/surface into incandescent vapour
meteorite (Terrestrial planet)
meteor large enough that a portion survives fall through atmosphere, strikes ground
carbonaceous chondrite (Terrestrial planet)
contains small glassy spheres called chondrules and volatiles
volatile (Terrestrial planet)
easily vaporized compounds, carbon dioxide, carbon monoxide, methane, ammonia
meteor shower (Terrestrial planet)
meteor display appear to originate from one region of the night sky, cometary debris
half-life (Terrestrial planet)
time required for half of radioactive atoms in a sample to decay
Comet (Jovian planet)
small ice body orbit the Sun, produce tails of gas and dust when they approach the Sun (tail always points away from the Sun)
Kuiper belt (Jovian planet)
collection of icy planetesimals orbiting just beyond Neptune to +50 AU, ~1000 discovered
Oort Cloud (Jovian planet)
hypothetical source of distant comets, icy bodies, spherical shell to 100000 AU from Sun
uncompressed density
density a planet would have if its gravity were not compressing it
ice line
boundary beyond which water vapour could freeze to form ice grains
condensation
growth of a particle by addition of material from surrounding gas, atom by atom
condensation sequence
distance from proto-Sun that different materials condense in the solar nebula
accretion
sticking together of solid particles to produce larger particle (e.g., snowflakes stuck together)
planetesimals
small body formed of dust grains (not gas) in the solar nebula, eventually protoplanet
protoplanet
coalescence of planetesimals in solar nebula, massive object, destined to become planet
gravitaional collapse
forming body, gravitationally captures gas rapidly from the nebula
heat of formation (in planetology)
heat released by infalling matter during planet body formation
differentiation
melting of most of a planet permitting separation of material according to density
outgassing
release of gasses from a planet’s interior (seen in modern-day volcanoes)
impact
meteor or comet body that reaches the surface of another Solar System object, usually violent
late heavy bombardment
crater evidence intense comet and asteroid hits in first 0.5by of solar system
near Earth objects (NEOs)
small solar system body (comet, asteroid) orbit that poses threat, collision