According to Stuart's photo and description, the asteroid would have been the size of an 18-wheeler. Buratti then calculated the crater's location and how big it would be. She and a graduate student searched through thousands of images of the scarred lunar surface. Finally, they came across an image of a mile-wide crater snapped by Clementine, a NASA space probe that took 2 million photos of the moon in the mid-1990s.
Paul Lowman, a lunar geologist with NASA, has seen Buratti's study and agrees that Stuart was right — the doctor had indeed witnessed a major asteroid impact.
The arrow points to the spot where an 18 wheeler sized rock hit the moon at just the moment a sentient life form on the Earth was looking at that spot. Good job, Dr. Stuart!