The study of the moon, stars, and other objects in space
An imaginary line that passes through a planet's center and its North and South Poles, about which the planet rotates.
The spinning motion of a planet about its axis.
The movement of an object around another object.
The path of an object as it revolves around another object in space
A measurement of distance from the Equator, measured in degrees north or south.
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.
The two days of the year on which neither hemisphere is tilted toward or away from the sun.
The day of the year that marks the beginning of spring in the northern hemisphere.
The day of the year that marks the beginning of fall in the Northern hemisphere.
One of the different shapes of the moon as seen from Earth.
The partial or total blocking of one object in space by another.
The blocking of sunlight to earth that occurs when the moon is directly between the sun and earth.
The darkest part of a shadow.
The part of a shadow surrounding the darkest part.
The blocking of sunlight to the moon that occurs when Earth is directly between the sun and moon.
The rise and fall of the level of water in the ocean.
The attractive force between two objects; its magnitude depends on the masses of the objects and the distance between them.
A tide in which the difference between high and low tide is the greatest. They occur when the Sun, Moon, and Earth are aligned.
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.
Any object that revolves around another object in space.
The orbit of a satellite that revolves around Earth at the same rate that Earth rotates.
A device built to observe distant objects by making them appear closer.
A round pit on the moon's surface.
Dark, flat regions on the moon's surface that were flooded with molten material billions of years ago.
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