Phases of the Moon

Moon’s Motion The moon’s motion is essentially the same as that of a star (rises in the east, sets in the west). The moon’s motion doesn’t keep pace with the sun or stars. It completes only 348º of an orbit in 24 hours. Falling 12º behind the sun each day, the moon completes a full circle (with respect to the sun) once every 30 days (actually 29). One month!

Determines the phase of the moon. The Sun-Moon Angle Determines the phase of the moon. 180o 0o Animation 270o

Waning Gibbous to Third Quarter Waxing Crescent First Quarter Waxing Gibbous to Full Full to Waning Gibbous Waning Gibbous to Third Quarter Waning Crescent to New

Waning Moon or Waxing Earth

The moon subtends an angle of ½ degree or the moon has an angular size of ½ degree

Craters - Virtually all of the Moon's craters were formed by meteoroid impacts about 4 billion years ago, in a heavy bombardment period. They are usually circular in shape and can vary in size. On the Moon the craters are usually named for famous astronomers, scientists, or explorers. The majority of craters seen through a telescope are concentrated towards the highlands and are very old. A few craters are visible in the maria which makes them younger than the event that formed the maria.

Highlands - These are the mountain- like structures on the Moon Highlands - These are the mountain- like structures on the Moon. They are the oldest part of the Moon's surface and were not formed by tectonic activity like the mountains on Earth. The highlands were formed by millions of meteorite craters, one on top of the other, that have pushed the top layer of the Moon's surface upward.

Maria - These are the dark areas on the Moon that look like "seas" Maria - These are the dark areas on the Moon that look like "seas". In Latin the word mare (singular) means sea. Maria are lowland, flat plains that resulted from the flow of lava from the Moon's interior when one or more large impactors struck the Moon and broke through the crust.

Some Definitions The limb is the edge of a body The terminator is the dividing line between night and day – it’s where sunrise and sunset occur These definitions hold for any body we study in the solar system

Measuring Mountain Heights C B M S T MB / SM = TB / CB Height of a mountain: MB CB is the radius of the moon TB is the distance from the terminator to the mountain’s base SM is the length of the shadow MB = (TB) (SM) / CB Note that there is no sea level on the moon, which is why we use the diameter; Convert measurements FIRST

Mons Pico Mons Piton Crater Plato Crater Cassini