This once normal star, having exhausted its internal supply of hydrogen, has expanded, growing into a gargantuan caricature of its former self called a red giant. It is dozens or hundreds of times its original size. Any nearby planets will be engulfe...

... ve the ground, the shock front from the blast penetrated to ground level and deposited tiny grains from the original meteor, melted and fused together. Researchers found these grains in Antarctica and dated them to 430,000 years ago. They believe thi ...