Our satellite stretches nearly 3500 km, about 1/4 of the diameter of the earth, it is on average 384.401 km away and it orbits the earth in 27,3 days. During one day the moon tilts by about 13,2° in the sky and so it rises above the horizon on average 53 minutes later every day. Because the earth circles the sun during the lunar orbit, the moon needs another 2 days to reach the same position as seen from us and in relation to the sun (phase of the moon). That is why the average time from one full moon to the next, `one moon month`, takes 29,53 days. During its rotation around the earth the moon also rotates once around its own axis and so shows the same face every time (`bound rotation`). The duration of one solar day on the moon equals nearly 15 earth days. Its orbit is on a 5° slant to the ecliptic and cuts it in two points, the rising and descending `lunar knot`. Only when the full moon or the new moon is close to one of these lunar knots (every 173 days), a solar eclipse (during new moon) or a lunar eclipse (during full moon) is possible. Because the lunar orbit moves (as does the earth's axis) like a gyroscope ("precessional"), darkness appears in a pattern of 223 moon months (6.585 days), the so-called Saros-cycle. This cycle was already known about in ancient times.  
The moon is about 1/4 of the diameter of the earth, but only 1/81 of its mass and does not have a strong magnetic field. The rocks of the moon surface are estimated to be 3-4 billion years old, which surpasses the oldest rock on the earth's surface by about 1 billion years. Because our companion has no protective atmosphere and therefore there is hardly any erosion, its surface is covered with craters made by meteorites.
Even now the history of its creation is disputed : Was it created along with the earth, at the same time or later ?   Did the earth catch it in its orbit ? Or - which today is considered to be the most probable cause - was the moon knocked out of the earth by a big planet ?  
The moon is the second planet which mankind has ever walked upon. On July 20th 1969 Neil Armstrong landed his spaceship Apollo 11 with the words "That's one small step for a man - one giant leap for mankind" and placed the first human foot on the moon. 

The moon was probably always used as a clock, because its phases could easily be observed. Many places of worship from ancient times, built according to the position of the sun and/or the moon (for example Stonehenge in the South of England) are records of the past.
The Greek goddess of the moon was Selene, later the goddess of hunting, Artemis, was responsible for some of her roles. Selene's Roman counterparts were Luna and Diana. In Christianity her position was partly taken over by the Virgin Mary. One period of the moon is about as long as the female menstrual cycle. So in ancient times all physical life of humans and animals was associated with the moon. In myths, the virginal and non-pregnant women were in the wake of and protected by the deity of the moon.  
The picture shows Selene as a woman with a crescent of the moon on her head, surrounded by seven stars which could represent the Pleiades. The bust is framed by a depiction of the zodiac. The period of 2 1/2 moon months splits a normal year into five parts (73 x 5 = 365), a division which also occurs in the fairytale of the rabbit and the hedgehog, as well as in the symbols of the Styrian moon-calendar or in the order of the days of the Blessed Virgin Mary. 73 times the luna rabbit runs before the blood squirts from its neck. This story probably depicts a lunar eclipse. The rabbit often symbolizes the moon in many myths and customs throughout the world. The Easter rabbit is also a symbol of the first full moon of spring. In the Nordic countries the moon is represented, among others, by the `varnished wolf`, by the trolls and by many figures in fairytales, for example the story "The Wolf and the Seven Goats" or "Little Red Riding Hood". In the background of these and other stories like "Sleeping Beauty", there are celestial movements, eclipses and calendar periods.
Monday (German: Montag, Italian: lunedi) is the day of the Moon.


Pic: Selene, Goddes of the Moon