Moon

Moon

The Earth's only natural satellite. The moon has a cold, dry orb covered with many lunar craters and strewn with rocks and dust. The moon has no atmosphere. But recent lunar missions have found plenty frozen water on the moon.

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Moon

opposition

Astronomy; Moon

A specific point in time when a moon or planet is 180 degrees away from the Sun, on the other side of the Earth. The Moon is full when it is in opposition (opposite of con, junction).

orbital eccentricity

Astronomy; Moon

The degree to which an elliptical orbit is elongated. Measured by the distance between the foci divided by the major axis.

palus

Astronomy; Moon

A Latin term meaning swamp that is used to describe topographical features on the moon which resemble dark plains or swamps.

parallax

Astronomy; Moon

The apparent motion of an observed object against the background caused by the movement of the observer. An example of this is the motion of the stars as seen from observatories on Earth.

partial eclipse

Astronomy; Moon

A lunar eclipse in which the Moon only partly enters the dark, umbral shadow of the Earth but is inside the secondary, penumbral shadow. Also refers to a solar eclipse when the Moon does not line up ...