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astronomy

The study of the moon, stars, and other objects in space

axis

An imaginary line that passes through a planet's center and its North and South Poles, about which the planet rotates.

rotation

The spinning motion of a planet about its axis.

revolution

The movement of an object around another object.

orbit

The path of an object as it revolves around another object in space

latitude

A measurement of distance from the Equator, measured in degrees north or south.

solstice

The two days of the year on which the noon sun is directly overhead at either 23.5 degrees South or 23.5 degrees North.

equinox

The two days of the year on which neither hemisphere is tilted toward or away from the sun.

vernal equinox

The day of the year that marks the beginning of spring in the northern hemisphere.

autumnal equinox

The day of the year that marks the beginning of fall in the Northern hemisphere.

phase

One of the different shapes of the moon as seen from Earth.

eclipse

The partial or total blocking of one object in space by another.

solar eclipse

The blocking of sunlight to earth that occurs when the moon is directly between the sun and earth.

umbra

The darkest part of a shadow.

penumbra

The part of a shadow surrounding the darkest part.

lunar eclipse

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

tide

The rise and fall of the level of water in the ocean.

gravity

The attractive force between two objects; its magnitude depends on the masses of the objects and the distance between them.

spring tide

A tide in which the difference between high and low tide is the greatest. They occur when the Sun, Moon, and Earth are aligned.

neap tide

A tide with the least difference between high and low tides. They occur when the Sun and Moon are at right angles to the Earth.

satellite

Any object that revolves around another object in space.

geosynchronous orbit

The orbit of a satellite that revolves around Earth at the same rate that Earth rotates.

telescope

A device built to observe distant objects by making them appear closer.

crater

A round pit on the moon's surface.

maria

Dark, flat regions on the moon's surface that were flooded with molten material billions of years ago.

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