Did a collision with a giant asteroid or comet change the shape of ... 30 times greater than average in the Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the ...

The asteroid, named 2012 BX34, measured between six and 19 meters in diameter (20 to 62 feet), said Gareth Williams, associate director of the US-based Minor Planet Center which tracks space objects.

He and three colleagues from the Extreme Environment Missions Operations could be flown to deflect the asteroid. “Earth has close calls all the time. The work we are doing is without a doubt ...