Earth Matters

Puzzling Evidence

September 2nd, 2014 by Mike Carlowicz

The answer to the August puzzler — Nagoya and the south-central coast of Japan — was puzzling even to Earth Observatory staff.


When we first posted the image on August 26, even we did not know what we were looking at. We had asked our colleagues at the Crew Earth Observations (CEO) office at NASA Johnson Space Center to give us an image that would stump our readers and would help us talk about a new citizen science project to identify the locations shown in nighttime images. They gave us an image that no one here immediately recognized.

In the process of presenting the answer last Friday (image below), we unwittingly demonstrated a quality-control portion of that ID program.


As you can see, we correctly labeled Nagoya, and then labeled the two cities on the left as Osaka and Wakayama. But as several readers from Japan pointed out, Osaka and Wakayama are farther west, and Kyoto also appears in the scene. Though we had consulted two different sources, maps of Earth at night are still pretty raw and the human eye can be tricked when looking at an unfamiliar landscape.

One of the protocols of the Cities at Night program is to ensure that every image is classified by multiple individuals working separately. It took several NASA staff and several readers to figure out the correct locations in this image. One of the goals of the citizen-science project is to figure out the optimal number of people needed to correctly classify an image. We didn’t intend to be a case study, but that’s what just happened.

Congratulations to Bruce Boucek, a data librarian at Brown University, for being the first reader to correctly identify Nagoya and the Chita peninsula of Japan. We asked him how he figured out the location, and he wrote: “I’ve been a map fanatic since I was a kid…When I was an undergrad, I had a particular interest in Japanese geography and as a PhD student I spent years working with remote sensing and satellite imagery. My initial hunch was that it was the eastern coast of Japan, but it didn’t look like Tokyo. I guessed that it was the next bay south and verified my hunch by looking at the NASA earth at night imagery. The clincher was the airports which have a significantly higher brightness signature.”

Three other readers — James Titmas, Jyo Sano, and Yumiko Stettler — also correctly identified the Nagoya area. Thanks also to Justin Wilkinson, Will Stefanov, and the CEO unit at NASA Johnson, a team that has to catalog and identify the thousands of images that come down from the International Space Station every year.

2 Responses to “Puzzling Evidence”

  1. David says:

    Was there an answer for July’s puzzler?