Listen to part of a lecture in an archaeology class.

(professor) It's well known among archaeologists that the civilizations in Central America and Mexico about 1,000 years ago, it's well known that they were accomplished astronomers. And how do we know this? Anyone? Joseph?

(male student) I know the Maya had a famous book and it has a chart in it saying when the planet Venus will rise and set?

(professor) Right! That's something we now call the Venus tables. So, the Maya came up with an incredibly accurate table of the phases of the planet Venus. But if you're not an astronomer, how are you going to understand it?

(male student) I know I couldn't.

(professor) I'm sure not many archaeologists could either. That\\\'s why some archaeologists also study astronomy. Actually, it's an entire branch of archaeology called archaeo-astronomy.

Combining archaeology and astronomy gives us insight into ancient cultures, because it helps us to understand part of their motivation as a culture. And the more we learn about ancient civilizations all over the world, the more we begin to see the importance of this field of research.

There are other clues that point to the importance of astronomy to the Maya, such as the placement of buildings, and, and how they were built. In fact, there's a building, one of the few round buildings built by the Maya that archaeologists studied and were puzzled about for years.

It looks remarkably like a modern observatory, but it wasn't until astronomers studied it that we found that the building was set up to pretty accurately track the planet Venus.

Now, there\\\'s a lesser-known site where archaeo-astronomy played a role right here in the United States. In what is now, Wyoming. It\\\'s called the Bighorn medicine wheel.

The whole structure, it is shaped like a huge wagon wheel laid out on the ground. It's made of many rocks arranged in a big circle with a pile of rocks in the center and 28 lines of rocks radiating from the center like spokes.

And naturally, we wanted to know why it was built, what purpose it served. We knew it was built by the people who lived in the plains, but we\'re not exactly sure when. It\'s estimated to be anywhere from 300 to 800 years old. So, before archaeo-astronomy revealed what's probably the wheels’ function, what do you think some of the hypotheses were?

(female student) Maybe they thought it was built for some sort of ceremony?

(professor) Okay, good! That was one hypothesis. Two things, though. It's at a very high elevation. Plus, it's covered in snow about 8 months a year. So, it's not very accessible.

(female student) But that wouldn't necessarily rule it out.

(professor) No, you're right. It wouldn't. Still…

(male student) Oh. Uh, did they think the rocks were used to hold down the edges of a tent?

(professor) Well, a tent or a teepee was another idea. But remember, it's high up in the mountains. And the whole thing is pretty large. Almost 25 meters across much bigger than the base of a tent would've been.

(female student) So, who finally figured out that it was related to astronomy?

(professor) While in the early 1970s, an astronomer learned about a different wheel, 5 or 600 kilometers south of the one in Wyoming. And how parts of that wheel lined up with the rising and setting sun on certain days of the year. The astronomer was John Eddy.

So, John Eddy traveled to Wyoming to study the Bighorn medicine wheel. He studied the lines of rocks. He took lots of measurements, and he found that when looking across the wheel, certain points on the wheel lined up with the points on the horizon where the sun rose and set during the summer solstice, in, in June.

And there were other alignments to three very bright stars when they appeared in the sky for the first time each year, 28 days apart from each other, same as the lunar month. So, what does this tell us?

(male student) It was used as a calendar?

(professor) Well, a calendar. I think an astronomical tool, an observatory that helped make a calendar would be more accurate. But before John Eddy's research, no one ever studied in that context, they never even considered it.

The discovery prompted archaeologists and astronomers to join forces more often. Together, we\'ve studied more structures in the Americas, other stone circles, wooden structures, earth mounds.

And we've learned that many were used for astronomical observations. And in examining those observations, we\'ve really expanded our understanding of the people who lived in the Americas hundreds of years ago.