Astronomy Answers: From the Astronomical Dictionary

# Astronomy AnswersFrom the Astronomical Dictionary

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The description of the word you requested from the astronomical dictionary is given below.

the First Quarter

The First Quarter is a phase of the Moon, equal to

1. [daily life] the period when about half of the lunar disk is illuminated, about a week after New Moon.
2. [astronomy] the instant at which the ecliptic longitude of the center of the Moon is exactly 90 degrees greater than that of the center of the Sun.