It is both familiar and mysterious. Throughout time it has regulated cycles on Earth, from our tides to crop gathering.
There is some debate as to how Earth gained its only satellite. The leading theory is that about 4.5 billion years ago an object roughly the size of Mars collided with Earth casting out debris that formed into our companion.
Due to the Moon’s synchronous rotation, where it rotates once in the same time it takes to travel around the Earth, we only ever see once side of it. Its features, such as the seas and craters are familiar to us night after night, phase after phase.
The Moon has several areas: the light areas are known as the highlands; the dark areas, maria (which is Latin for “seas”), are impact basins; and, of course, there are many craters from billions of years of space debris hitting the surface.
The first human to set foot on the moon was Neil Armstrong. There were six landings between 1969 and 1972, and 12 astronauts walked on the Moon’s surface. In total, the astronauts brought back 382 kg of moon rock and soil for study.
Though no humans have been to the moon since 1972, our companion is still being vigorously studied. There have been several spacecraft sent out to by several countries, including China, Japan and India, as well as the European Space Agency. The United States sent out the Lunar Reconnaissance Orbiter and LCROSS in 2009, and LADEE in 2013. China's Yutu rover landed on the Moon in 2014. Although there are no concrete plans for humans to return to the Moon, there have been calls for human exploration of our nearest and most familiar neighbour. Many of the Moon’s secrets are still waiting to be uncovered.