The moon Flashcards
Waxing
Right Side of moon is showing
Waning
Left side of moon is showing
Gibbous
Big chunk of moon is showing
Crescent
Small slice of moon is showing
First Quarter Moon
Right quarter is showing
New moon
Can’t see moon
Third Quarter Moon
Left quarter of moon is showing
What causes phases of the moon?
Relative positions of the earth, moon, and sun
Sidereal Period
Orbit time to match star positioning, 27.3 days for moon
Synodic Period
How long it takes to moon to be by same stars in the same phase, 29.5 days
Umbra
Full shadow cast by earth, total darkness
Penumbra
Some light from the sun can be seen but most is blocked by earth
Lunar Eclipse occurs when
The moon crosses into the umbra of earth, turns blood red since the light in the umbra is from the sunset/sunrise edges
Why is the sky blue?
When sunlight reaches earth’s upper atmosphere the blue light scatters from the beam
Sunset and Sunrise Colors
The remaining unscattered light, heads towards sides of earth, deficient in blue
Phase of Lunar Eclipse
Full Moon, 2-3 eclipses per year
Solar Eclipse
When moon casts shadow on earth
Phase of Solar Eclipse
New Moon, 2-3 per year
Why is it hard to see a solar eclipse?
Because the moon’s shadow is small and will spend much time over the ocean
Why don’t we see solar eclipse every new moon?
Moon doesn’t rotate our equator so most times new moon is not blocking sun
Annular Eclipse
When the moon passes directly between earth and the sun but moon is too far from earth to completely cover the sun, can see ring of sun around moon
Density of Moon
3.34 g/cm^3
Internal composition of moon
outside is covered in craters and maria, then crust, mantle, and core, weak magnetic field
Lunar Maria
Dark planes (spots) formed by volcanic activity, lava filling meteor crater basins
Far side of moon
very rugged, no large smooth planes
Moon’s crust
solid rock, 50-60km on near side, 70-100km on far side
Moon’s Mantle
1000km, mainly solid
Moon’s core
350-500km in radius, iron and nickel, partially molten, smaller in comparison to earth’s core v. earth’s size
How did we find out the interior of the moon?
Seismic waves collected by seismographs left by Apollo missions
Gravity Recover and Interior Laboratory (GRAIL)
Gravitational field analysis, help understand interior of moon, launched in 2011
Olivine
Mineral found on earth and moon, key component of earth’s upper mantle, in moon’s mantle, gives info about interior and age, geological processes
Lunar Reconnaissance Orbiter (LRO)
2009, designed to map moon’s surface, temp and composition of surface, discovered water deposits near lunar poles, identifies good landing spots
Lunar Crater Observation and Sensing Satellite (LCROSS)
2009, sent ot confirm presence of water ice at shadowed craters, 600,000,000 m^3 of water ice
Artemis I
used orion space craft, first step towards returning humans to the moon, uncrewed to test pace launch system, 25 days and orbited moon in 2022, heat shield and nav. was good, blocked solar radiation well
Artemis II
First crewed test flight to moon since Apollo, 4 astronauts to confirm spacecraft works correctly, 10 days
Artemis III
Landing on the moon, 2025, establishes sustainable presence on moon
Origin of the moon options
Double Planet theory, fission theory, capture theory, large impact theory
Double Planet Theory
argues earth and moon formed together as a binary system from the primordial disk of gas and dust that formed the solar system, differences between earth and moon composition don’t support this theory
Fission Theory
Suggests the moon was part of the earth and spun off due to rapid rotation, discredited due to lack of evidence, also moon doesn’t orbit on the spin plane of earth, but densities are consistent
Capture Theory
moon formed elsewhere and was later captured by earth’s gravity, unlikely since are compositions are similar, not likely since it can’t slow does without contact or 3rd object
Large Impact Theory
most widely accepted theory, moon is formed by debris from a glancing blow between earth and a mars sized object (Thea), 4.5 billion years ago, disk of debris formed together to make moon (bits on earth and Thea), moon’s composition is similar to earth’s outer layers (formed from earth), material liquified from intense heat to form a sphere