Australia's Wolf Creek Crater is much younger than previously thought and has allowed scientists to calculate how often large meteorites hit the Earth.
The study was carried out by an international team of scientists led by Professor Tim Burrows of the University of Wollongong. They found that an iron meteorite weighing about 5,000 tons struck the Earth 120,000 years ago, more than 2 times earlier than previous estimates (300,000 years).
“The amount of energy released from the impact of the meteorite was about 30-40 times greater than from the bomb dropped on Hiroshima,” said Dr. Burrows.
The crater has been preserved thanks to low erosion levels in the Tanami Desert.
Given that the oldest reliable archaeological evidence of human arrival in Australia dates back to around 65,000 years ago, hardly anyone was hurt in the impact.
Compared to the Moon, there are very few impact craters on Earth. First, it is our atmosphere that burns small meteorites before they reach the surface. Secondly, this is due to wind, rain, rivers and oceans, which destroy the resulting craters.
Wolf Creek Crater is one of the best-preserved craters on planet Earth, due in part to its relatively young age and location. It is located in a geologically stable desert that covers about two-thirds of Australia's land area. This means that the meteorite craters found here have the best chance of a long life.
“The arid region of Australia is an excellent area for the preservation of not only craters, but also meteorites, for example, in the Nullarbor Plain, they have been found in large numbers,” said Dr. Burrows.
Rocky or metallic asteroids, passing through the Earth's atmosphere, become meteors, burn brightly due to friction and, if the fragments reach the Earth's surface intact, then they become meteorites.
Due to the favorable conditions of the Australian continent for the preservation of meteorite craters, Dr. Burrows' team calculated the frequency of impacts of large meteorites.
Very large meteorites, measured in kilometers, only affect the Earth every few million years. But meteorites measuring tens of meters, like the one that created the Wolf Creek crater, are much more common.
Professor Tim Burrows of the University of Wollongong led an international team that discovered that Wolf Creek Crater was likely created by a meteorite impact 120,000 years ago.
Adding to the study data on six other Australian craters, the dates of which are known, the scientists received a disappointing result.
“We have had an alarming result - at least one meteorite hitting about 25 meters occurs every 180 years,” said Dr. Burrows.
Fortunately, most of the Earth's surface is still uninhabited. Although, the incident in Chelyabinsk, when a 20-meter meteorite exploded before hitting the ground, suggests that no one is protected.
Wolf Creek Crater in northern Western Australia is the second largest crater in the world to contain meteorite fragments.
Of course, most meteorites fall into the oceans, but it is impossible to collect statistics on them.