Of course, it affects our world in other ways too - those of you who live near the ocean will have first hand experience of the huge tides caused by the moon's gravitational pull. And it's dominating presence in the night sky has been celebrated in literature and art worldwide since the birth of humanity.
No wonder it is so significant- it's the largest moon in the solar system relative to its host planet.
So have you ever wondered how the Earth came to have such a sizeable object orbiting around it?
Various theories about the Moon's formation have been put forward over the years. One of the leading theories is that the Moon is the result of a collision between the early Earth and another planet-sized object, but there has been little hard evidence. However, last week researchers announced results to support this idea, based on analysis of moon rock samples.
The collision theory suggests that an object about the size of Mars, which has been called 'Theia', crashed into the Earth while the Solar System was forming. This caused a lot of material from the Earth to fly off into space, where gravitational attraction bound it together again around what remained of Theia.
This theory has a lot of support from scientists because because it explains many facts about the Earth-Moon system.
For example, the Earth has a large iron core, but the Moon is much less dense, so it is unlikely that they formed at the same time from the same material. The difference in densities could be because the collision knocked off only outer parts of the Earth, which are less dense and contain less iron than its core.
The collision theory also explains why the moon orbits in the way that it does. If the Earth's gravity had just captured a passing object with no impact, it would most likely have ended up with a different orbital pattern.
But there is a problem with the collision theory - the material that the moon is made of should be different chemically from the Earth, because it should also contain material from Theia. However, scientists have tested moon rocks that arrived on Earth as meteorites, looking particularly at the ratios between certain forms of particular elements such as oxygen, titanium and silicon, and there don't appear be any significant chemical differences from Earth rocks.
Aa group of researchers has recently taken a new approach. The problem with lunar meteorites is that they are not fresh and are likely to have become chemically altered since arriving on earth many years ago, so Dr Herwatz and his team have been examining some of the moon rocks collected by the Apollo astronauts. They announced last week that levels of a particular form of oxygen in these rocks were found to be significantly higher than in similar Earth rocks.
So is this proof that the Moon was formed by a collision with Theia? Maybe! Dr Herwatz believes it to be strong evidence that the collision took place, and of the chemical composition of Theia. But scientists are always reluctant to claim 100% certainty – there is always the possibility of other explanations for the result, and some are unconvinced. Nevertheless, this research will certainly stimulate debate on the subject and inspire further investigation.
Perhaps we are now one step closer to understanding just how the queen of the night skies was born.
1. NASA
2. NASA/JPL-Caltech
3. NASA
More information about the formation of the moon:
http://www.space.com/19275-moon-formation.html Various theories about the formation of the moon
http://www.sciencemag.org/content/344/6188/1146 Announcement of research results
http://phys.org/news/2014-06-isotopic-evidence-moon-formation-earth.html Report about the new research results
http://www.scientificamerican.com/article/lunar-rock-chemistry-argued-to-reveal-how-the-moon-formed/ Comments and opinions about the new research