Feeling Hollow on the Inside
Sunday
There are three types of craters: Impact craters are formed when meteorites strike the surface of a planet or moon, or, less commonly, when other moons or planets strike the surface. Volcanic craters are formed by the outward bursting of volcanic activity, but should not be confused with calderas, which are the collapse of a volcano’s magma chamber. Finally, explosion craters can be formed by explosions either natural or artificial.
Monday
The Vredefort Impact Structure in South Africa is the world’s largest at 186 miles wide, though 2 billion years of natural surface changes have made the bowl-shape of this massive meteorite strike less distinct. Notably, this area is also one of the world’s largest gold sources.
Tuesday
If an impact crater is big enough – at least 300 km wide – it graduates to the title of “basin.” On Earth, only Vredefort qualifies, but other planets and moons have plenty. Mercury’s Caloris Basin is 1,525 km wide, while or our own moon’s South Pole-Aitken Basin is a whopping 2,400 km wide.
Wednesday
Without wind, water, weather, lava, and shifting plates to erase them, even small impact craters don’t go anywhere. Our moon still bears all the marks of meteorites which have struck it throughout its life, including some 4 billion+ years old.
Thursday
On Mexico’s Yucatan Penninsula, the ring of underwater caves, or centotes, marks the edge of the impact crater from the massive meteorite whose effects are suspected of killing all the dinosaurs (and many other creatures) 66 million years ago.
Friday
Craters, whether formed by volcanoes or the occasional meteorite strike, often make beautiful lakes if they fill with water. These are not always safe for recreation, however, since volcanic crater lakes have been known to be highly acidic and belch toxic gasses.
Saturday
Enormous 160 ft.-deep craters recently found in Siberia and known as “giant escape craters” appear to be from explosions caused by methane escaping the permafrost thawed by climate change.