This is Scientific American 60 Second Science. I'm Emily Schwang.

More than 900 years ago, the Pueblo people were thriving in New Mexico's Chaco Canyon.

While they were there, the region experienced what the whole... thriving in New Mexico's Chaco Canyon.

While they were there, the region experienced what the whole country is looking forward to

on August 21st, a total solar eclipse.

Theirs took place in the year 1097, and they may have left a record of the event.

I spotted this very peculiar petroglyph, which was a round object.

Kim Malville is a retired solar astronomer from the University of Colorado Boulder.

In 1992 he and colleagues were leading a field course in Chaco Canyon when he noticed

a unique carving on the south side of a rock.

Which was a round object with loops coming out of it.

And this struck me as maybe this was a image of the sun with the corona in a very active state and maybe at that time

there was what is known as a coronal mass ejection. That's when a giant cloud of

plasma spirals off the sun's surface because of a solar flare.

It was somewhat foolhardy, I suppose, on our part to suggest a particular explanation for it.

But Malville knew that he had a testable

hypothesis. Astronomers know that the region had a total solar eclipse on

July 11th 1097. During the brief darkness, the sun's Corona would have been

visible. Solar activity increases and decreases on a roughly 11-year

cycle, so Malville used various historic records to find out what was happening in 1097.

And all of these indicated that in 1097, the sun was indeed in a state of very high activity and thus we couldn't prove that this was actually

a image of the Corona but we could not falsify our hypothesis.

...