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Sarah Parcak: How Can Satellite Images Unlock Secrets To Our Hidden Past?

Jun 26, 2020

Part 3 of the TED Radio Hour episode TED Radio Wow-er

There may be hundreds of thousands, if not millions, of undiscovered ancient sites. Sarah Parcak wants to locate them — from space.

About Sarah Parcak

Sarah Parcak is a space archaeologist, who uses satellite images to locate hidden ancient sites around the world, such as ancient Egypt, the Roman Empire, and more. Since winning the 2016 TED Prize, she launched an online crowdsourcing archaeology platform called GlobalXPlorer.

Sarah is also an associate professor of Anthropology at the University of Alabama at Birmingham, where she founded the Laboratory for Global Observation. She holds a BA from Yale University and an MA and PhD from Cambridge University.

Activity Guide - Printable PDF

Activity 1: What Will Survive?

Archaeologists know that organic stuff (things that are or used to be alive) is susceptible to decay. If you've ever seen or made a time capsule, this is why they need to be airtight and dry. Archaeologists don't find organic remains very often, because it generally undergoes significant decay within a fairly short time. At most sites, fragile artifacts and organic remains are lost, and we'll never know what stories they could have told. Inorganic remains survive better, although they too can rust, erode, or otherwise break down in unstable conditions. Only if a site is covered over and sealed quickly, as Pompeii was by volcanic ash, may both organic and inorganic remains survive.

Here's some definitions and examples: Organic (once living) remains survive well only if protected (by hot/dry, airless, waterlogged, and very cold or frozen environments, or if sealed in volcanic ash). Organic remains turn to dirt easily. Examples of organic remains include human and animal bones, plants, objects and features made of plants and animals (like food, paper, wood, leather). Inorganic (never living) remains survive well in relatively airless conditions, although they too can break down when exposed to the elements. Examples of inorganic remains include clay, stone, cement, plastic, glass, and metal.


  • Just a pencil and paper! Though a clipboard would be helpful too.

How To Do It:

  • Make a list of the furniture and objects in a room at home. Carefully note whether each object is organic or inorganic. If an object has parts of both, make a note of which parts are which (for example, the legs of a chair are organic, the rest is inorganic).
  • Assume 1,000 years have passed, and the room has not been specially preserved like Pompeii. List what will be left after all the organic materials decay.
  • Summarize what you think an archaeologist in the future will be able to say about your room, your family, and you as an individual. Will your name survive? Will your taste in colors or music or books survive? Will the archaeologist know for certain what your gender or age is?
  • Another thing to think about is what objects would not survive that are also very important to you—and that say a lot about who you are and how you live.
  • If you liked the activity, you can do it again for a different room at home and compare the surviving artifacts in both rooms. Would an archaeologist now have a better understanding of how you live? Did the kind of room make a difference, for example did more of the kitchen survive as compared to your bedroom?

Source: Adapted from The Archaeological Institute of America

Activity 2: Backyard Photo Scavenger Hunt

Archaeology is all about documenting a site. Sarah Parcak is especially cool because she does this from space, using cameras and sensors on satellites. For this activity, the site is your backyard (or any area outside that your family is okay with you exploring). We're not going to photograph your site the way archaeologists do, but we are going to test our observation skills and get creative.


  • Digital camera or phone camera
  • If you don't have either of those, no worries! You can always do a quick sketch of what it is you'd like to capture.

How To Do It:

  • Search your site for objects that you think best represents each of the adjectives below. You can take the pictures in any order. Bonus points if it's an object that would survive, like we learned about in the first exercise.
  • You're looking for something: smaller than you, taller than you, yellow, cheerful, lonely, pointy, soft, clean, dark, light, moving, shiny, colorful, unique, cold, warm, magical.
  • See if a friend or family member can guess which picture goes with which adjective. Or if more than one person did the activity, take turns showing each other a picture and guessing the adjective. See if they can guess whether it represents "soft" or "dark." If they guess the adjective correctly, ask them what about your photo made them think that was the answer. If they did not guess it correctly, what made it not look like the answer.
Copyright 2020 NPR. To see more, visit https://www.npr.org.


So we're going to move on from the dolphins. And this next idea that you brought us is about uncovering something hidden as well. But this time we're going to talk about uncovering human history with archaeologist Sarah Parcak.

GUY RAZ, BYLINE: Yeah, I mean, man, how can I even begin? I think you know Sarah, too. She uses tools of space exploration to dig into our past - into the past here on planet Earth.

ZOMORODI: Yeah, and what I love about that is that space exploration, like, it's not exactly the first thing that comes to mind when you hear archaeology. But for Sarah, the idea kind of runs in the family. So let's listen.


SARAH PARCAK: My name is Sarah Parcak. And I am an archaeologist.

RAZ: And as an archaeologist, Sarah Parcak searches for traces of past civilizations hidden beneath the Earth for thousands of years.

Do you think that every civilization eventually becomes buried and hidden?

PARCAK: Yeah, I think that all civilizations do. I think there are also a lot of civilizations and cultures out there that we don't know about yet.

RAZ: Sarah has discovered an ancient amphitheater under the airport in Rome.

PARCAK: Like, the equivalent of an ancient cineplex.

RAZ: An unknown temple in Petra.

PARCAK: Could be a temple, not sure.

RAZ: And the lost city of Tanis in Egypt.

PARCAK: It was Egypt's capital for about 400 years.

RAZ: And how Sarah discovered these sites? Not by digging but by building on a technique used by her grandfather.

PARCAK: My grandfather Harold Young was one of the pioneers of using aerial photography in forestry. And so by the time I got to college, I thought if Grampy did this for forestry, I bet lots of people have done this for archaeology. It would be fun to see what he did. And I really - I feel like I was the first kid in the candy store. You know, virtually no one had used it before in Egypt.

RAZ: So after Sarah graduated, she started to experiment with a method that has now completely revolutionized archaeology. And as she explained on the TED stage, it's earned her a special title.


PARCAK: I'm a space archaeologist. Let me repeat that. I am a space archaeologist. This means that I use satellite images and process them using algorithms and look at subtle differences in the light spectrum that indicate buried things under the ground that I get to go excavate and survey. And by the way, NASA has a space archaeology program, so it's a real job.


PARCAK: This is from a site south of Cairo. So let's have a look from space. You can't see anything. When we process the image, this is what you see. This rectilineal form is an ancient tomb that is previously unknown and excavated and you all are the first people to see it in thousands of years.

RAZ: OK, so how does it work? How do you use satellite images to find, you know, hidden places?

PARCAK: So satellite imagery allows us to do two things. It allows us to look at sites with a fresh pair of eyes. But why they're really valuable is that they record information in different parts of the light spectrum that we simply can't see with our human eyes. So imagine there's a stone wall somewhere in Italy that dates to the Roman period, so roughly 2,000 years ago. And you'd walk over a field and you wouldn't see it.

RAZ: Yeah.

PARCAK: Well, that stone wall, which may be under a meter or so of Earth, it affects the overland topography. So the roots going down, they couldn't go as deep because they'd be stopped by the stone wall. And so processing the satellite data, you can actually map out and see those changes. And you start seeing straight lines. And those straight lines form structures, which definitely aren't natural. So just as an example, we got a hold of new satellite imagery for most of the pyramid fields. And when I started processing it, it feels like cheating. You can see everything.

RAZ: How many sites have you guys found using pictures from satellites?

PARCAK: I'm at the point where I've lost count. It is in the many thousands, but I don't know anymore.

RAZ: Wow.


PARCAK: I believe we have barely scratched the surface in terms of what's left to discover. In the Egyptian Delta alone, we've excavated less than one one-thousandth of 1% of the total volume of Egyptian sites. When you add to that the thousands of other sites my team and I have discovered, what we thought we knew pales in comparison to what we have left to discover. When you look at the incredible work that my colleagues are doing all around the world and what they're finding, I believe that there are millions of undiscovered archeological sites left to find. Discovering them will do nothing less than unlock the full potential of our existence.

ZOMORODI: When we come back, we'll hear more from Sarah about how her work can help us all discover more about the planet we call home. I'm Manoush Zomorodi. And you're listening to the TED Radio Hour from NPR. Stay with us.


ZOMORODI: It's the TED Radio Hour from NPR. I'm Manoush Zomorodi. And today on the show - ideas for the whole family with my predecessor, Guy Raz. In addition to previously hosting this show, he is the host of the kids' science podcast Wow In The World. Hey, Guy.

RAZ: Hello.

ZOMORODI: So before the break, we were hearing from you and Sarah Parcak, the space archaeologist, about how many ancient sites she has already begun to uncover using satellite imagery. Let's get back to your conversation with Sarah.

RAZ: All right.


RAZ: I mean, what you're saying is we only know a tiny bit about our past. Is that true? I mean, is most of our history hidden?

PARCAK: I would say, yes, because history is always written by the winners. And, yeah, people are living in places where they've always lived for thousands of years. Look at places like Rome and Istanbul and Cairo. Those cities are layers upon layers upon layers of history. So I think we've taken a lot for granted about who we are and where we've come from. We think living in this very modern age with smartphones and the Internet and sort of this whole world of knowledge at our fingertips, we know everything. But the more and more we delve into the past, the more we realize that we don't and that it has a lot of lessons to teach us for today.


PARCAK: I wish for us to discover the millions of unknown archeological sites around the world. By creating a 21st-century army of global explorers, we'll find and protect the world's hidden heritage, which contains clues to humankind's collective resilience and creativity. So how are we going to do this? We are going to build an online crowdsourced, citizen science platform to allow anyone in the world to engage with discovering archaeological sites and protect them. By creating this platform, we will find the millions of places occupied by the billions of people that came before us. Acknowledging that the past is worth saving means so much more; it means that we're worth saving, too. And the greatest story ever told is the story of our shared human journey, but the only way that we're going to be able to write it is if we do it together. Thank you.


ZOMORODI: Oh, I love that line where she says means that we're worth it, too.

RAZ: So great.

ZOMORODI: So I have to ask, if you could go on an archeological dig, the ancient civilization of your choice...

RAZ: Yup.

ZOMORODI: ...Where would you go?

RAZ: I think I would want to do something, like, way, way, way back, like early humans or, like, our - or even our human predecessors. They were human-like creatures at least 7 or 8 million years ago, and that's what we know of. And we've only discovered, you know, the remains of, like, a teeny number of human-like species. And so there's, like, very little doubt that we have so many more to discover, like, hundreds, thousands of species. And that would just be amazing to go on one of those digs.

ZOMORODI: I want to call Sarah and ask her if I can go visit one of those places in Peru if she could hook me up.

RAZ: Oh, my God. Right?

ZOMORODI: That'd be cool (laughter).

RAZ: I know. So cool. Transcript provided by NPR, Copyright NPR.