Life in the Universe quiz 10

2 most important factors

distance from sun and size

size leads to

atmosphere, magnetic field, plate tectonics, and volcanism

venus vs earth

same size, venus closer to sun, venus receives 2x solar energy

CO2

earths is in ocean/carbonate rocks, venus in atmosphere

why is venus so hot

has 200,000x more CO2 then earth

habitable zone

range of distances at which worlds similar to earth could exist, liquid water on surface if big enough

stars

brighten as they age, causing h.z. to move outward

mars-like

possible pockets of subsurface liquid water, life below groundrf

free-floating planets

possible surface water if thick enough atmosphere

titan-like

if like can use other liquids as its medium (methane/ethane)

europa-like

subsurface oceans (top frozen, maybe life underneath)

venus never had water (why it lacks water)

unlikely, both plants should have had water incorporated in interiors by water-bearing asteroids and comets

had water but lost it (why venus lack water)

solar ultraviolet breaks apart water molecules, lightweight H escapes to space and water is lost

evidence for lost water

100x as much deuterium on venus then earth, suggests water loss with deuterium, had enough water for oceans

deuterium

heavier then hydrogen, less vulnerable to thermal escape

runaway greenhouse effect

if earth moved to Venus’s orbit

size

strong enough gravity to retain atmosphere, enough internal heat for outgassing

free floating planet

also named ROUGE planet, no star

h.z moves outward

fusion with sun shrinks/heats solar cover over time

worst case of end of earth habitability

1 billion years due to onset of moist greenhouse effect

best case of end of earth habitability

3-4 billion years when runaway greenhouse effect becomes inevitable

global warming

term used for the current ongoing rise in earths global average temperature

climate change

resulting changes in local and regional climates

carbon dioxide/greenhouse gases

make earth warmer then it would be otherwise

inevitable conclusion

expect our planets global average temperature to be rising

spectal class

type of star in the order of OBAFGKM

O star

biggest, hottest, brightest, but have the shortest lives

M star

smallest, coolest, dimmest, but have the longest lives