The Moon

The Moon is the only natural satellite of our home planet Earth. It's quite big with 3,474km in diameter or a bit more than a quarter of Earth's own 12,756km. If you are considering a visit be prepared to travel at least 363,104km or go as far as 405,696km in case you pick a wrong moment. Once there you will certainly feel much lighter because gravitational pull on the Moon's surface is about six times weaker than Earth's.

Lunar cycle

The Moon completes one orbit around the Earth in 27 days 7 hours and 43 minutes, but when we calculate in variations characteristic for Sun-Earth-Moon system, we get the perception of Moon phases that repeat every 29 days 12 hours and 44 minutes creating one lunar cycle.

Moon phases

Moon or lunar phases are the result of changes in geometry of the Sun-Earth-Moon system. For example, Full Moon appears when the Sun and Moon are on opposite sides of the Earth. When they are on the same side of the Earth then we have the so called New Moon which is invisible at night and also known as Dark Moon. Names of Moon phases as they happen are: New Moon, Waxing crescent, First quarter, Waxing gibbous, Full Moon, Waning gibbous, Third quarter, Waning crescent and again New Moon…

Blue Moon

In modern times Blue Moon is the term related mostly with two meanings. One definition calls it the Blue Moon on a rather rare occasion when the second Full Moon appears in a calendar month. Next such appearance is on December 31, 2009. By other definition Blue Moon is the third Full Moon in a season of four Full Moons and we will witness it on February 21, 2008.

Lunar eclipse

A lunar eclipse should not be confused with Moon phases although it has very close relation with one of them. It occurs whenever the Moon passes through the Earth's shadow. This can happen only when the Sun, Earth and Moon are in a total or very close alignement and the Earth is in the middle. Therefore a lunar eclipse always happens with the Full Moon and may be partial or total.

Sides of the moon

While orbiting around the Earth, Moon shows us the same face all the time with only small variations. For that reason we speak about two sides of the moon with one faced the Earth called the "near side" and the other opposite side called the "far side". Do not confuse far side of the Moon with another well known term, dark side, as it refers to the side that is not being illuminated by the Sun at a given moment. Actually, during the New Moon phase the dark side is the one facing the Earth – the near side.

Apollo missions

NASA started the Apollo program in 1961 with the goal to land astronauts on the Moon. The first mission to succeed was the Apollo 11 with Neil Armstrong and Buzz Aldrin that landed on the Moon on July 20, 1969. We would also like to mention here the third man on that mission, Michael Collins, that stayed in the command module. There were six Apollo missions altogether that included manned landing and the last one Apollo 17 was in 1972.