Finding the Alphabet from Space

Posted on Mon, January 8, 2018

A few years ago, NASA Earth Observatory science writer Adam Voiland started noticing familiar shapes in satellite images of Earth. First, it was a plume of smoke in the shape of a V. Soon upper and lowercase letters revealed themselves in craters, clouds, and rivers. Since then, Voiland has searched through thousands of NASA’s satellite images and astronaut photography, looking for the entire alphabet in images taken from space. I recently spoke to him about his quest for the Earth’s alphabet as well as his work at NASA’s Earth Observatory.

Tell me about NASA’s Earth Observatory. What is the mission of the website?

Our official mission statement is to "share with the public the images, stories, and discoveries about the environment, Earth systems, and climate that emerge from NASA research, including its satellite missions, in-the-field research, and models." Day-to-day, I like to think of the job as "come in and write about the most jaw-dropping satellite image (or data visualization) we can find." Sometimes that means I might be writing about the latest image of a hurricane or the damage it caused. Another day the topic might be new maps of the global spread of "bare ground," or the sheer beauty of changing fall colors.

The Enhanced Thematic Mapper on Landsat 7 acquired this image of Akimiski Island in James Bay on August 9, 2000. The island appears to form the letter "D."

Spot the letter D? The Enhanced Thematic Mapper on Landsat 7 acquired this image of Akimiski Island in James Bay on August 9, 2000. Credit: NASA Earth Observatory.

Why are satellite images important to scientists, researchers, and the public?

With satellite missions, it's the perspective that is the key. Satellites make it possible to see the "big picture." For instance, scientists could set up networks of sensors on the ground to sample air quality or put buoys in the ocean to measure its salinity, but these tools would only sample a very small area. If you put the right satellite or fleet of satellites into orbit to take those same measurements, you might be able to get global maps of air pollution or salinity. There's a tradeoff between how much coverage a sensor gets and the resolution of the observations, so what scientists really need is a combination of satellite data and data from the ground (or aircraft) to study these issues on a global scale.

What inspired you to start looking for the alphabet in satellite images?

It was really just a whim. I saw an odd smoke plume over Canada that looked to me like a V, or maybe a 2, and it occurred to me that it might be fun to look for the whole alphabet. Years later, after finding both uppercase and lowercase sets of letters, I can say it really was fun. I feel like I know Earth's surface a lot better now than I did when I began this project.

The letter B, found in an image of the Arkansas River and the Holla Bend Wildlife Refuge, captured by the Landsat 8 in 2014.

The letter B, found in an image of the Arkansas River and the Holla Bend Wildlife Refuge. This was captured by the Operational Land Imager (OLI) on Landsat 8 on August 4, 2014. Credit: NASA Earth Observatory. 

How many satellite images did you have to go through to find the whole alphabet?

That's actually a tough question to answer. I did a lot of browsing through imagery on sites like Earth Explorer from the U.S. Geological Survey, Worldview from NASA, Google Earth, Snapsat, and Libra. I wasn’t counting. I would say probably thousands, though I glossed over many very quickly.

What was your approach to finding letters?

I used a mix of strategies. Often I focused on particular types of terrain that I thought would create the shapes I needed to find certain letters. I knew that rivers tend to make meanders and oxbows that might be useful for letters like C, B, and R. Likewise, fjords tend to make straight lines, so I spent a lot of time looking in Greenland and Patagonia for X's and A's. If I was looking for features that were cloud-free, I tended to search on Google Earth, but if I was looking for features caused by the clouds, I turned to Worldview or browsers that hadn't filtered clouds out. I also looked at maps that focused on key themes like vegetation or rivers and screened out background "noise.”

An astronaut captured this photograph of an artificial island at the southern end of Bahrain Island on January 23, 2011. The island appears in the shape of the letter C.

An astronaut captured this photograph (and the letter C) of an artificial island at the southern end of Bahrain Island on January 23, 2011. Credit: NASA Earth Observatory. 

What was the hardest letter to find? What was the easiest?

R was the hardest, by far. It turns out that nature doesn't like to put curved, straight, and diagonal lines right next to each other. Meanders in rivers can do it quite nicely, but with the children’s book, we had to make sure that the features were large enough that they would print well. I have dozens and dozens of really great letters that weren't large enough to print at high quality. Thanks to volcano calderas and impact craters, O’s seemed to turn up all over the place. 

What do you hope children will get out of your book ABCs from Space?

I hope it helps kids learn their letters, of course, but at a more basic level, I really hope it encourages kids, parents, and teachers to get outside and really observe and appreciate the natural world. I did this ABC search using satellite imagery, but I've also had a lot of fun searching for letters in leaves, streams, pebbles, bugs, and anything else I could find while out in the woods with my two-year-old son. I would love to see parents doing that sort of thing, especially in a time when we’re all constantly surrounded by gadgets and technology. 

To learn more about Adam Voiland’s work visit or read his book ABCs from Space: A Discovered Alphabet (Simon & Schuster, 2017).