Astronomers at Lund University in Sweden have reconstructed the history of meteorite impacts on Earth in the past 500 million years. According to the scientists’ findings, published in the journal Proceedings of the National Academy of Sciences, large collisions in the asteroid belt had little effect on the number of collisions with the planet, which refutes the generally accepted theory.
Researchers dissolved nearly ten tons of sediment from the bottom of ancient seas in acid to isolate grains of chromium oxide, a substance found in meteorites. In total, scientists analyzed nearly 10,000 different meteorites. They found that only one of the 70 largest asteroid collisions (in the mid-Ordovician about 460 million years ago) that occurred in the last 500 million years has increased the flow of meteorites falling to Earth.
Several thousand meteorites are known to fall to Earth each year, and scientists have documented about 63,000 space rocks. Meteorites come from the asteroid belt between Mars and Jupiter, where large collisions have formed families of celestial bodies. However, those that have fallen to Earth make up only a small area of orbital space in the belt.