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The Moon is Earth's only natural satellite, orbiting at an average distance of 384 399 km (238,854 mi; 30 Earths across).It faces Earth always with the same side.This is a result of Earth's gravitational pull having synchronized the Moon's rotation period with its orbital period (lunar month) of 29.5 Earth days.
The average length of a calendar month (a twelfth of a year) is about 30.4 days. This is not a lunar period, though the calendar month is historically related to the visible lunar phase. The Moon's distance from Earth and Moon phases in 2014. Moon phases: 0 (1)—new moon, 0.25—first quarter, 0.5—full moon, 0.75—last quarter
The approximate age of the Moon, and hence the approximate phase, can be calculated for any date by calculating the number of days since a known new moon (such as 1 January 1900 or 11 August 1999) and reducing this modulo 29.53059 days (the mean length of a synodic month).
20th: Summer solstice – longest day of the year in the Northern Hemisphere. 22nd: Full Moon. ... The moon lines up with planets in the morning on June 1. Show comments. Advertisement. Advertisement.
The formal lunar day is therefore the time of a full lunar day-night cycle. Due to tidal locking, this equals the time that the Moon takes to complete one synodic orbit around Earth, a synodic lunar month, returning to the same lunar phase. The synodic period is about 29 + 1 ⁄ 2 Earth days, which is about 2.2 days longer than its sidereal period.
The first day of summer changes from year to year, arriving on June 20, 21 or 22. That's because the earth's astronomical year is actually 365.25 days long, writes Space.com. That's also when the ...
As a result, the time it takes the Moon to return to the same node is shorter than a sidereal month, lasting 27.212 220 days (27 d 5 h 5 min 35.8 s). [18] The line of nodes of the Moon's orbit precesses 360° in about 6,793 days (18.6 years). [19]
It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, e.g. Earth around the Sun. Periods in astronomy are expressed in units of time, usually hours, days, or years.