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crescent

(Encyclopedia)crescent, emblematic representation of the quarter moon. The crescent and star, ancient Byzantine symbols that became the emblems of Constantinople, were also assumed as the standard of the Ottoman Tu...

Aristarchus of Samos

(Encyclopedia)Aristarchus of Samos ărˌĭstärˈkəs, sāˈmŏs [key], fl. c.310 b.c.–c.230 b.c., Greek astronomer and mathematician of the Alexandrian school. He is said to have been the first to propose a heli...

center of mass

(Encyclopedia)center of mass, the point at which all the mass of a body may be considered to be concentrated in analyzing its motion. The center of mass of a sphere of uniform density coincides with the center of t...

Endymion

(Encyclopedia)Endymion ĕndĭmˈēən [key], in Greek mythology, young shepherd, loved by Selene (the moon). In one version of his legend, he asked Zeus for immortality and perpetual youth. Zeus consented on the co...

Sin, in ancient Middle Eastern religions

(Encyclopedia)Sin sĭn [key], moon god of Semitic origin, worshiped in ancient Middle Eastern religions. One of the principal deities in the Babylonian and Assyrian pantheons, he was lord of the calendar and of wis...

week

(Encyclopedia)week, period of time shorter than the month, commonly seven days. The ancient Egyptians used a 10-day period, as did the French under the short-lived French Revolutionary calendar. In many regions a f...

inclination

(Encyclopedia)inclination, in astronomy, the angle of intersection between two planes, one of which is an orbital plane. The inclination of the plane of the moon's orbit is 5°9′ with respect to the plane of the ...

Friedrich, Caspar David

(Encyclopedia)Friedrich, Caspar David käsˈpär däˈfēt frēˈdrĭkh [key], 1774–1840, German romantic landscape painter. After studying painting in Copenhagen he visited various scenic spots in Germany and ch...

weight

(Encyclopedia)weight, measure of the force of gravity on a body (see gravitation). Since the weights of different bodies at the same location are proportional to their masses, weight is often used as a measure of m...

Mercury, in astronomy

(Encyclopedia)Mercury, in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon a...