298 Baptistina - Extinction Event Theory

Extinction Event Theory

In 2007, a study by William F. Bottke, David Vokrouhlický and David Nesvorný proposed that several known asteroids can be regarded as the "Baptistina family" because they share similar orbital elements. Further, the study argues that the family is the remnant of a 170 km (110 mi) parent asteroid that was destroyed in a collision with a smaller body some 80 million years ago, with Baptistina itself being the largest remnant. Until recently, it was believed that this collision event occurred 160 million years ago. This led to a suggestion that one fragment from the event may have eventually become the K–T impactor believed to have caused the Cretaceous–Paleogene extinction event that brought about the extinction of the dinosaurs 65 million years ago.

Concerns were originally raised about this theory, in part because very few solid observational constraints exist of the asteroid or family. Recently, it was discovered that Baptistina does not share the same chemical signature as the source of the Cretaceous–Paleogene boundary (K–T boundary). While this finding made the link between the Baptistina family and K–T impactor more difficult to accept, it did not preclude the possibility.

However, in 2011 data from the Wide-field Infrared Survey Explorer revised the date of the proposed collision which broke-up the Baptistina parent asteroid to about 80 million years ago. If correct, these data mean it is very unlikely that the K–T impactor was part of this family of asteroids, as it typically takes many tens of millions of years for an asteroid to reach a resonance with Earth and then collide, much more than the 15 million between this breakup and the collision of the K–T impactor. "As a result of the WISE science team's investigation, the demise of the dinosaurs remains in the cold case files," said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program.