FINDING MOON ROCKS
Why astronauts brought lunar rubble back to Earth
WORDS SCOTT DUTFIELD
More than 200,000 miles from Earth is a round lump of rock that has fascinated humankind for thousands of years: our natural satellite, the Moon. In 1969, humans made the valiant journey beyond our atmosphere and across the vacuum of space to bring some of it home. Before astronauts walked on the Moon’s surface, it was widely believed that Earth’s natural satellite was merely a space rock that had drifted too close to Earth’s gravitational grasp and become trapped within it. However, thanks to the rocks brought back to Earth for study, the theory behind the Moon’s origin has shifted in favour of the giant impact hypothesis.
The majority of the Moon is made up of anorthosite, a calciumrich rock that consists mostly of a mineral known as plagioclase feldspar. These minerals are formed from the solidification of hot molten lava. It’s thought that throughout the Moon’s existence, countless impacts from craterforming meteorites have pockmarked its surface, which was once a raging ocean of molten rock before it cooled and solidified. Moon rocks brought back by astronauts have also revealed the biggest collision in the Moon’s history.