Astronomy Ch 9 FINAL: Cratered Worlds (Moon and Mars)

giant impact hypothesis

moon formed in collision between earth and mars sized planet, ejected material left in space formed it

moon’s composition similar to

earth’s crust

what supports giant impact hypothesis

slight differences in oxygen isotope ratios between lunar rocks and earth rocks

why does moon have synchronous rotation

tidal forces

synchronous rotation

rotation rate equals revolution (orbital) rate

why is the lunar orbit bigger

earth’s rotation makes bulge at the equator, making acceleration in moon’s orbit

lunar month increases by

0.014 seconds every century

how did mercury and the moon get water ice in crater shadows

comet delivered it after they formed

atmosphere of moon and mercury

almost totally airless, combination of temperatures and low escape velocity

do the moon and mercury have erosion

no

only terrestrial planets with magnetic fields

moon and mercury

does the moon have a magnetic field

not since billions of years ago

why is the moon’s surface smooth?

molten lava filled low areas and covered up craters, making hardened lava lakes

maria

hardened lava lakes, dark smooth patches on the moon made from black basalt

Mercury’s surfaces smooth from

past volcanism, few inactive volcanoes have been identified