Craters are bowl-shaped indentations in the Earth's crust. They can form due to explosions or volcanic activity, but the largest and most notable ones are usually formed when a meteorite comes crashing to the ground. Meteorites reach the Earth's surface every day, but most of them are the size of a dust speck. Many others burn up entirely before reaching the ground and are known to us as "shooting stars" as they streak across the sky. The large meteorites that do reach the surface of the planet can have a tremendous impact. Here's where to go for an up-close-and-personal view of these indentations that tell a tale from the distant past.
Morokweng in South Africa
The Morokweng crater measures around 43 miles in diameter and is located in the Kalahari Desert in the northern part of South Africa. While the crater is obscured from view by the sands and debris of the desert, it was discovered in the mid-1990s because it caused unusual magnetic patterns. Scientists used isotopic dating to determine that the crater is about 145 million years old.
Manicouagan in Canada
The Manicouagan crater is located in Quebec, Canada, and is the sixth-largest in the world. It measures 52 miles in diameter, which is big enough to make for some pretty impressive photographs when viewed from space. The shape that the crater makes when viewed in these aerial photos has given in the nickname the "eye of Quebec," and the crater is now home to the Manicouagan Reservoir, which is the fifth-largest reservoir in the world and a source of hydroelectric power.
Acraman in Australia
The fifth-largest crater is the Acraman crater in South Australia. It measures 56 miles in diameter. This crater has a distinctive shape that makes it unusual. Instead of being an even bowl shape, the Acraman crater has different elevations throughout the site. Scientists date its likely occurrence at 600 million years ago, predating most of the lifeforms researchers have found in the fossil record. There is a dramatic change in the type of microscopic fossils found in the rock record that coincides with the Acraman crater's meteoric impact, so some believe this event triggered significant changes to life.
Popigai in Russia
The Popigai crater in Russia is about the same size as the Acraman, measuring around 56 miles in diameter. This crater is located in the far north of Siberia and is believed to be about 35 million years old. In the 1970s, the crater was discovered to be the site of an extensive collection of diamonds. However, the information remained classified for nearly 30 years, and the remote location made it easy to keep the secret. Exploration has suggested there are several trillion carats worth of diamonds hidden within the crater, and to date, only a small fraction have been extracted.
Sudbury in Canada
The Sudbury crater measures a remarkable 81 miles in diameter, which makes it the third-largest in the world. Unlike many of the craters on this list, the Sudbury crater is easily visible in Ontario without trekking to uninhabited lands. In fact, the impact responsible for creating the crater also forced the creation of the nearby mountains. The crater, which is deformed and therefore somewhat of a geological mystery, has been the site of lucrative metal mining.
Chicxulub in Mexico
The Chicxulub crater is the second-largest in the world and measures 93 miles in diameter. It is located on the Yucatan Peninsula in Mexico and is the result of a meteorite crash approximately 65 million years ago. This event lines up with the apparent extinction of many dinosaur species, and researchers believe that the Chicxulub crater may be the result of an extinction-causing event.
Vredefort in South Africa
The most massive crater on earth is the Vredefort crater located in South Africa. It measures a mind-boggling 99 miles in diameter and is estimated to be 2 billion years old. The impact of the geological upset has left the soil in the center of the crater unsuitable for farming, so the land is covered with forests and hard mountains, protecting it from erosion. Visitors can walk through layers of geological history when they view the crater's many layers of upturned earth.