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earth's shape

spherical, but not perfect


imaginary line around which earth spins


spinning of Earth on its imaginary axis, which takes about 23 hours and 56 minutes to complete and causes day and night to occur

Earth's poles

north and south pole


Earth's yearlong elliptical orbit around the sun


elongated, closed curve that describes Earth's yearlong orbit around the Sun

earth's axis tilt

23.5°, causes seasons


either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length, dates are March 20, 21 in the spring and September 22, 23 in the fall


either of the two times of the year when the sun is at its greatest distance from the celestial equator, dates are june 21, 22 in the summer which is the longest and december 21, 22 in the winter which is the shortest

appearance of moon

changes in this caused by revolution

moon's rotation

27.3 days to complete full rotation

moon's revolution around earth

27.3 days to complete full circle

new moon

moon phase that occurs when the Moon is between Earth and the Sun, at which point the Moon cannot be seen because its lighted half is facing the Sun and its dark side faces Earth

waxing crescent

A phase of the moon coming after a new moon and before a 1st quarter moon that is a lit up crescent on the right

first quarter

the right half of the moon appears lit

waxing gibbous

a phase of the moon that comes after a 1st quarter moon and before a full moon where almost all of the moon is lit up from the right to the left, except a small bit on the left.

full moon

phase that occurs when all of the Moon's surface facing Earth reflects light.

waning gibbous

a phase of the moon that comes after a full moon and before a last quarter moon where all of the moon is lit up except for a small bit on the right side of the moon that we can see.

last quarter

We can see exactly 1/2 of the Moon's lighted surface, during the latter half of the night. (see left half)

waning crescent

phase of the moon that comes after a last quarter moon and before a new moon where only the left sliver of the moon is visible and has a crescent shape


one celestial body obscures another

cause of eclipse

the revolution of the moon

solar eclipse

occurs when the Moon passes directly between the Sun and Earth and casts a shadow over part of Earth


a region of complete shadow resulting from total obstruction of light


a fringe region of partial shadow around an umbra

lunar eclipse

the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon


dark-colored, relatively flat regions of the Moon formed when ancient lava reached the surface and filled craters on the moon's surface

impact theory

Theory states that the moon was formed around 4.6 billion years ago when a Mars sized object collided with earth, throwing gas and debris into orbit. after this, the debris condensed and formed the moon

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