50,000 years ago the desert of Arizona was open grasslands with areas of small forests filled with woolly mammoths and giant ground sloths.
At this time, a giant meteorite, 162 feet wide, fell from the sky and smashed into the Earth.
Over the years, the climate of that area has changed into a desert and the impact site from the meteorite is still plainly visible.
It is believed that the space rock struck the land at the speed of about 28,000 mph.
Most of the meteorite vaporized during the impact, but scientists have found some pieces inside the crater.
Check out this neat animation illustrating the most likely path the meteorite took on its way to Earth.
Geez...kind of freaky to think about this happening today!