42 terms

The Moon Phases/Eclipses

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the moon revolves around earth from
west to east in an elliptical orbit
its period of revolution around earth
27 1/3 days
average distance from earth
386 000 km
nearest to earth
perigee
farthest from earth
apogee
moons orbit compared to earths
not in exactly the same plane as earths orbit, the angle between the 2 orbits is about 5 degrees

the moons orbit is inclined about five degrees to the plane of earths orbit
the suns diameter is
nearly 400 times the moons diameter
reason why sun and moon appear to be about the same size in the sky
the sun is nearly 400 times farther away from earth than the moon
the moon rises in the
east and sets in the west
every 24 hrs the moon
moves about 13 degrees eastward along its orbit thus earth must rotate an extra 13 degrees more than 369 ti see the moon rise each night

turning 13 takes about 50 minutes for earth the result is the moon rises about 50 minutes later each day and sets about 50 minutes later as well
when the moon is opposite the sun
it is seen mostly in the night sky
when the moon is between earth and the sun
it is seen mostly in the daytime sky
phases
daily changes in the moons appearance/ changing shapes of the moon
why do phases occur
moon is seen by reflected light
moon is in orbit around earth
from new moon to full moon
2 weeks
waxing/all dark to all light
waxing
new moon to full moon
all dark to all light

part of the moon that is visible increases
from full moon to new moon
2 weeks
waning/all light to all dark
waning
full moon to new moon
all light to all dark

part of the moon that is visible decreases
at new moon phase
the lighted half faces away from earth and the moon cannot be seen
at crescent phase
only one edge of the lighted half faces earth
>phase when less than half of the moon is visible from earth
at quarter phase
half of the moon facing earth is half lighted and half dark
at gibbous phase
almost all of the bright half faces earth
>phase when more than half of the moon is visible from earth
at full moon phase
the entire bright half faces earth
>whole face of the moon is visible
order of phases
1. new moon
2. waxing cresent
3. waxing quarter
4. waxing gibbous
5. full moon
6. waning gibbous
7. waning quarter
8. waning cresent
moon rises and sets
50 min later each day
1/27th movement in orbit, phase to same phase = 29.5 days
difference between moons orbital plane and earths orbital plane
5 degrees
moon phases are caused by the
relative change in reflected light as seen from earth
terminator
dividing line between the illuminated and shadowed part of the moon
the orbit of the m around e is tilted by 5 degrees from the
ecliptic (earths orbital plane) so it down not always line up with the earth and sun
one rev/rot around axis
4 weeks 27.3 days (side real month)
time required for moon to return to same position relative to the sun/same phase
29.5 days (synodic month)
lunar eclipse
the moon moves into the earths shadow blocking the sunlight that reflects off the moons bright surface
>the earths shadow begins as a narrow bank of darkness at the edge of the moon then gradually moves to cover the entire moon
>the moon does not go completely black since a small amount of light does continue to fall on the moon
>as this reflected light enters the earths atmosphere only the red wavelength of visible light passes through which gives the moon a red appearance

during a total lunar eclipse earths atmosphere bends the suns light enough so it hits the moon by only the red and orange colors can get through all other colors are filtered out by the atmosphere
solar eclipse
the moon moves between the sun and the earth casting its shadow on a portion of the earth
>occur far less often than lunar eclipses
>need a full moon line up
eclipses occur when
one celestial object casts a shadow on another.
celestial objects casts two types of shadows
umbra- a complete shadow
penumbra- a partial shadow
what is the phase of the moon during a solar eclipse
new moon because it occurs midday/noon
what is the phase of the moon during a lunar eclipse
full moon because 12 am/midnight
why do we not have total solar or total lunar eclipses every month
A lunar eclipse occurs when the Moon enters the Earth's shadow. A solar eclipse occurs when the Moon's shadow falls on the Earth. They do not happen every month because the Earth's orbit around the sun is not in the same plane as the Moon's orbit around the Earth.

not always coming in perfect alignment because 5 degree incline plane, significant distance difference
why can our moon which is smaller than the sun completely block the light of our sun
400 times farther away
400 times the size of the sun
would you experience more total solar eclipses if you lived on earth or on the moon
earth because on earth you have to be on that small part to see it where shadow falls whereas on the moon you can see it anywhere
solar eclipses
total/annular/partial
never last more than 7.5 min
at totality the solar corona can be seen
2/3 solar eclipses a year
lunar eclipses
can be total (umbra) or partial (penumbra)
full moon events, can be seen anywhere on earth as long as full moon
last as along as 1 hr
only red and orange bend through atmosphere
2-3 lunar eclipses a year