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abstraction > mathematical concept > unit > time unit

time unit
subject			fact

time unit	is a unit of time
	is a kind of unit
unit	has historical origin
	represents

Kinds of time unit :

• aeon (3 facts) (eon) - In astronomical terms, 1000 million years.
• cosmic year (3 facts) - Time the Sun takes to "orbit" in galactic rotation: about 225 million years.
• day (2 kinds, 12 facts) (d) - An interval of 86400.51 seconds, unless otherwise indicated.
• month (3 kinds, 12 facts) - The period of one complete synodic or sidereal revolution of the Moon around the Earth; also a calendrical unit that approximates the period of revolution.
• second unit (4 kinds, 15 facts)
• week (3 facts) - An arbitrary period of days, usually seven days; approximately equal to the number of days counted between the four phases of the Moon. (See lunar phases.)
• year (8 kinds, 25 facts) - A period of time based on the revolution of the Earth around the Sun.