The Moon Flashcards
what is the dark areas known as?
maria (singular mare)
what are the two types of general surface?
- lowlands, mostly maria
2. highlands, vast mountainous regions
what is the size of the moon compared to earth?
1.2% mass of earth
one quarter the diameter
what is the moons albedo?
low, 7%
what are lowlands?
grey plains that occupy 15% of moons surface. expanses of volcanic lava
Where do earth-facing maria lie between?
2 and 5km below mean radius of moon
why are there very few maria on far side?
earths gravitational effects on moon
why are mare young by lunar standards?
have less craters than elsewhere, 3-3.9 billion years old.
what are the typical mare features?
sinuous rills: lava channels, often originating from craters in high regions of maria and flow into lower lying areas
wrinkled ridges: result from folding in the surface layrrs of maria
dome-like features: with summit craters
How old are highlands?
most ancient: 4.5 billion years old, as old as moon
higher albedo than mare
what are the features of highlands?
extensively cratered, less dense than mare, remnants of lunar crust.
no mountain ranges, main lunar boundaries are circular maria
what dominates the entire surface of the moon?
craters
what is the processes of craters being formed?
1: missile strikes surface, shock waves sent into target and projectile itself. projectile vaporizes, and material ejected at high velocity.
2. next stage material thrown out at lower velocity, excavating crater, plume of material is ejected from crater
3. ejected material falls back to surface and rum of crater formed by uplift
what is the Regolith?
surface of moon covered by layer of dust and broken rock, overlying solid bedrock
loose, footprints last long time.
how is regolith created?
meteoric bombardment
does moon have atmosphere?
no, escape velocity too low (2.4 km/s)
what is density?
3.3 g/cm^3
how much smaller is the core of moon to earth?
smaller fraction (20%), than earth (50%)
how thick is the crust?
50-100 km at appolo sites, thicker on far side where no maria
composition of mantle?
rigid- no plate tectonics
composition of core?
partially molten at present , heat flow from interior, radioactive decay
why is there a lack of large molten core?
no dynamo, no weak overall magnetic field
why is the surface as it was formed?
no tectonic activity/erosion, only altered by lava flows and bombardment
how as moon formed?
grazing impact by mars sized object. large body was differentiated with iron core. partially vaporised by impact. bodys iron poor mantle formed hot disk around earth, which coalesced to form moon. result moon with large angular momentum and low overall iron abundance, low content of volatile elements.
