According to a new study, the asteroid that collided with the Earth 65 million years ago, provoking significant changes, here included the extinction of dinosaurs and other species, is believed to have been part of a much larger asteroid that was fragmented following a collision 160 million years ago.

The science journal Nature published today the work of Prof. Bottke, David Vokrouhlicky of Charles University in Prague and David Nesvorny of the Southwest Research Institute, containing their theory and details of their views. The scientists state that after a large asteroid met a smaller one – but still of impressive dimensions- in the innermost region of the asteroid belt, a part of the former was pulled by a gravitational force and traveled within tens of million years towards Earth, eventually crashing the Yucatan Peninsula, resulting the Chicxulub crater and leading to the extinction of the dinosaurs. 

The team used computer simulations and mathematic calculations to determine the orbits of hundreds of asteroids 160 million years ago –give or take 20 million years- and thus discovered that they came from one single location, a parent asteroid.

“If you look at how far the asteroids have traveled, you can use that distance like a clock to tell you how old the breakup is,” Prof. Bottke explained.

The tea of researchers calculated that the parent asteroid was 170 kilometers in diameter and collided a smaller one, having a 60-kilometer diameter, at a distance of almost 200 million kilometers from Earth, in the innermost region of the asteroid belt between Mars and Jupiter. Though there is little knowledge of that happened with the smaller one, the larger asteroid is believed to have torn in 300 parts larger than 10 kilometers in diameter and 140,000 asteroids larger than one kilometer wide. The former asteroid used to form the Baptistina asteroid family.

Due to the “Yarkovsky effect”, through which the asteroid absorbed sunlight and further re-radiated it as heat, the refugee part of the crashed asteroid traveled during tens of millions of years towards  dynamic regions in the solar system, known as resonances. In this area it encountered gravitational forces from Jupiter and Mars that altered its orbit and propelled it towards the Earth, its journey being some million years long.

Using information provided by studies made 10 years ago, researchers discovered that the composition of the Chicxulub crater, made of carbonaceous chondrite was alike the one of the parent asteroid. They talk of a more than 90 percent probability that the asteroid that hit the Earth 65 million years ago is part of the Baptistina parent, and of a probability of more than 70 percent that the lunar crater Tycho, was a result of a collision of another part of the parent asteroid, that was involved in the impact 108 million years ago.

The odds of an asteroid impact similar to that Earth encountered 65 million years ago are once in 350 million years, while another collision alike that in the asteroid belt of 160 million years ago could happen once in every 200 million years.