It is not hard to see, when we look at the moon, what impact the asteroids had on its surface. Thousands of craters are visible on the moon which were left behind by asteroid strikes ad pockmarks. On the contrary, on our planet, there are only 190 confirmed craters. Over the past 4.5 billion years the moon and the Earth have suffered similar instances of injury even though the evidence does not match up.
Thursday there was a study published in Science in which the rate at which asteroids struck the Earth and the moon was determined. From about 1 billion years ago to 290 million years ago it was relatively constant. When that 290 million years mark hit, the rate became 2.6 times higher. Today the rate of asteroid impact persists.
An associate professor at the University of Toronto and study co-author Rebecca Ghent, Ph.D., comes with an explanation why we are in this period where asteroid impacts are this frequent. She says that a collision of astronomical objects in the asteroid belt between Jupiter and Mars might be causing an asteroid to break up into more tiny pieces.
Do you want to know why our planet does not have these many craters? Or, at least, undiscovered ones? Well, that is because of weathering and erosion on the planet’s surface. These processes were believed by scientists to be the reason by the oldest craters of the Earth could not be found. Such craters are the relatively recent 50,000-year-old Meteor Crater in Arizona and a very very old crater, the massive, 2-billion-year-old Vredefortdivot in South Africa.
The craters that once existed are no longer visible because of the movement of the tectonic plates which hide this evidence of the asteroid strikes.