The Moon (Luna)

Our companion in space, the Moon, is certainly a first target for the beginning astronomer. It is easy to locate, it’s bright and it continually changes its phase every day. These phases have heralded many an important cultural event, and even today some refer to people as being “ moonstruck”. Nearly every culture recognised the Moon’s influence on our tides, and it also provided us with our first calendar, with the word “month” coming from the word “Moon”. In addition to this, due to folklore regarding the effect that the full Moon has on individuals, the word “lunatic” is also derived from “Luna”.

Situated at a distance of 384,401 kilometres from earth, it orbits the Earth every 29.5 days, and due to it having a rotation of 27.3 days, we generally see the same side of the Moon facing us, no matter the time of month or year.

Following 10 years of analysis of the lunar rock and soil samples returned from the Apollo missions, it emerged that the Moon was created by a Mars sized planet, glancing against the early Earth about 4.5 billion years ago, which sped up the rotation of our planet and also sent a spray of super hot vapour into orbit. This vapour cooled into a ring of debris, and eventually as millions of years passed by, the debris congealed and eventually thickened to form the Moon.

Compared to Earth it is a dead world, with no obvious continuous erosion, mountain building or volcanic activities, however, sky watchers sometimes report unusual events, called TLP’s (Transient Lunar Phenomena), which include sightings of mists and sudden glows on its surface.

The naked eye shows dark and light areas on its surface. Ancient astronomers believed that they were seas just like here on Earth and named them using the Latin name for “sea”; Mare (i.e. Mare Crisium). These terms are still used, despite the fact that we are now aware that these “seas” are in fact smooth sheets of congealed lava that once flowed on its surface.

When viewing the Moon, you will notice that the many Lunar features you observe will change their appearance over the two weeks that sunlight shines on them. To get the best contrast views with a telescope or binoculars, target the areas around the terminator (where the bright part meets the dark part).