Topic 2- The Moon Flashcards
What is a sidereal month
Is the time the moon orbits the earth as respect to the background stars
How long is a sidereal month
27.3 days
What is a synodic month
The period between the same phase this is longer as the earth is also orbiting the sun
How long is a synodic month
29.5 day
What is the shape of the moon
An oblate spheroid
What is the subtended angle of the moon
O.5 degrees
What is the mean diameter of the moon
3500 km
How much of the moons surface can you see from earth
59%
What causes the moons synchronous orbit
Gravitational forces slowed the moons period of rotation down until it became tidally locked to it orbital period
How often do the moons phases repeat
29.5 days
How many days does it take for the moon to orbit earth once
27.3
What is durinal libration
Allows us to see more of the moons surface when moon near horizon because observer is seeing it from a higher angle this allows us to see the eastern and western limbs
What limb can be seen at moon rise
Eastern limb
What limb can be seen at moon set
Western limb
What is latitude libration
The equator of moon is tilted from its orbital plane which allows observer to see over northern and southern polar regions
What is longitude libration
The moons elliptical orbit and rotations allows us to see more of the eastern and western limbs
When the moon becomes bigger what is it called
Waxing
When moon starts to become smaller what is it called
Waning
How were craters formed
From heavy bombardments of impacts from materials in space, meteorites and comets
How were Maria and terrae formed
Objects impact moon
Lava then escapes surface
Lave then cools forming basalt
The highlands where left untouched forming terrae
How were mountains formed
By impacts that released magma under the early lunar surface
How were valleys formed
By ancient lava flows, collapsed lava tubes or geological faults
How do you recognise craters
Consists of a raised wall or limb a slope on the inside leads to crater floor which is below outside terrain often have a central peak
How do you recognise Maria
Dark grey areas
How do you recognise terrae
Bright areas which are higher than Maria- hilly and mountainous
How do you recognise mountains
Very high peaks
How do you recognise valleys
Long depressions on the moon surface can reach up to hundreds of km long but only a few km wide
