These images were taken using a Kodak DC3400 digital camera at a resolution of 1760 x 1168 pixels.  The moon was 8 days old at the time apart from two out of the last four on this page which were taken when it was 10 days old.

Diameter

1/4 Size of Earth

1/6 g

Max  +105°C
Min  -155°C

27.3 Earth days

27.3 Earth days

4,500 million years

3.3 g/cm³

None

2.38 km/sec

The Moon is the earth's only moon (hence its name - the Moon) but it's a comparitavly large satellite since it's diameter is about ¹/₄ the size of Earth's.  This means it's sometimes known as a double planet - not to the same extent as Pluto, but still enough to warrant it as a nickname.  As to it's formation, there have been many theories, such as it being captured from elsewhere, separation from the Earth or independent formation.  The most likely theory, however, is that a big body - about the size of Mars - smashed into the Earth and the moon was formed from the Earth's and the asteroid's debris.

The 'lunar crust' was formed near the start of the moon's history by it's outer layers melting to form a layer of magma which covered the whole moon and then subsequently cooling.  There are now many craters and basins in the Moon, resulting from the many asteroids and comets which have hit it.  Although in it's history it had some volcanic activity, this has now pretty much ceased and the Moon is sometimes referred to as a 'fossil planet'.  This isn't entirely true though as earthquakes have been recorded deep below the Moon's crust.

The oldest Moon rock we have is 4,500 million years old but there is evidence to suggest that the Moon is even older.  The first human telescopic observation of it though was in 1610 by (guess who!) Italian astronomer Galileo Galilei.   Then, a few centuries later in 1959 the Soviet Luna 2 became the first spacecraft to reach (or rather, crash into) the Moon.  The first landing followed in 1966 by the Luna 9.  Then the manned Apollo 11 reached the moon in 1969, followed by the rest of the Apollo missions (12-17) - except of course for Apollo 13.