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A lunar phase or Moon phase is the apparent shape of the Moon's directly sunlit portion as viewed from the Earth. Because the Moon is tidally locked with the Earth, the same hemisphere is always facing the Earth.
Timekeeping on the Moon is an issue of synchronized human activity on the Moon and contact with such. The two main differences to timekeeping on Earth are the length of a day on the Moon, being the lunar day or lunar month, observable from Earth as the lunar phases, and the rate at which time progresses, with 24 hours on the Moon being 58.7 microseconds (0.0000587 seconds) faster, [1 ...
It was the first time that a Chinese lunar probe directly entered an Earth-to-Moon transfer orbit without orbiting the Earth first. [24] After the launch, Chang'e 2 arrived in its lunar orbit within 4 days and 16 hours. Later, the probe lowered its orbit to 100 km (62 mi), with a perilune of 15 km (9.3 mi). [25]
A lunisolar calendar was found at Warren Field in Scotland and has been dated to c. 8000 BC, during the Mesolithic period. [2] [3] Some scholars argue for lunar calendars still earlier—Rappenglück in the marks on a c. 17,000 year-old cave painting at Lascaux and Marshack in the marks on a c. 27,000 year-old bone baton—but their findings remain controversial.
In lunar astronomy, libration is the cyclic variation in the apparent position of the Moon that is perceived by observers on the Earth and caused by changes between the orbital and rotational planes of the moon. It causes an observer to see slightly different hemispheres of the surface at different times.
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month. Animation of the Moon as it cycles through its phases, as seen from the Northern Hemisphere. The apparent wobbling of the Moon is known as libration.
The lunar nodes are the two points where the Moon's orbital path crosses the ecliptic, the Sun's apparent yearly path on the celestial sphere.. A lunar node is either of the two orbital nodes of the Moon; that is, the two points at which the orbit of the Moon intersects the ecliptic.
A solar calendar year has 365 days (366 days in leap years).A lunar calendar year has 12 lunar months which alternate between 30 and 29 days for a total of 354 days (in leap years, one of the lunar months has a day added; since a lunar year lasts a little over 354 + 1 / 3 days, a leap year arises every second or third year rather than every fourth.)