MASSIVE MOON CRATER

How Tycho, our Moon's most prominent crater, formed

- SCOTT DUTFIELD

It’s estimated that there are millions of craters sprawled across the surface of the Moon. However, one stands out among all the lunar impact sites visible from our vantage point here on Earth. Named after the Danish astronomer, Tycho Brahe, the Tycho crater has long intrigued astronomers. Its high walls, flat floor and central peak make it seem like a city on Earth’s natural satellite. Even the Victorian selenographer (someone who charts the Moon) Thomas Gwyn Elger called it “the Metropolitan crater of the Moon”.

The walls of the crater span 51 miles wide and plummet around 2.92 miles to its floor. Incredibly, this is small in comparison to the Moon’s biggest impact site, the South Pole-Aitken basin, which stretches 1,550 miles in diameter. At its centre is a rocky peak that reaches 1.24 miles into the absent air. The curious peak is characteristic of large craters, the result of rock that was compressed by the massive force of the impact, then immediately rebounded upwards.