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Earth Matters

August Puzzler

August 26th, 2014 by Mike Carlowicz


Every month on Earth Matters, we offer a puzzling satellite image. The August 2014 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.

How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money, but, we can promise you credit and glory (well, maybe just credit). Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In the credits, we’ll acknowledge the person who was first to correctly ID the image. We’ll also recognize people who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a  day to give others a chance to play.

Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.


UPDATE (September 4) – The answer to this puzzler was the Image of the Day on August 31. We also posted a blog entry about the challenges in solving this puzzler.

Glacier-calving in Lakes Versus the Sea

August 22nd, 2014 by Adam Voiland

Tidewater glaciers—glaciers that flow from inland mountains all the way into the sea—are perhaps best known for birthing new icebergs in spectacular fashion. As members of James Balog’s Extreme Ice Survey team captured in this clip (above) of Ilulissat Glacier in western Greenland, calving events can feature huge chunks of ice tumbling into roiling waters and be accompanied by loud booming and splashing sounds.

However, tidewater glaciers aren’t the only type of glacier that calve. The ends of lacustrine, or lake, glaciers also break off periodically. Such glaciers gouge depressions in the ground, and those holes fill with melt water to become proglacial lakes. While many of these lakes are small and ephemeral, some are large enough to serve as the backdrop for sizable calving events.

University of Alaska glaciologist Martin Truffer captured this sequence of images (below), which show a calving event at Yakutat Glacier in southeastern Alaska on July 16, 2009. “What we see in the video is a huge iceberg breaking off and rotating. I don’t have a good estimate of the size, but the part of the front that broke of is at least one kilometer long. I think it is quite unusual to see such large ice bergs overturning in lake-calving glaciers. Mostly, they just break off and quietly drift away,” Truffer noted in an email.

There are some key differences between calving events at tidewater and lacustrine glaciers. Tidewater glaciers tend to have much steeper calving fronts than their freshwater cousins. Also, lake water is generally much cooler than seawater, and there is less water circulation in lakes due to the absence of tides. As a result, tidewater glaciers calve much more frequently and are much less likely to have floating tongues of ice, which are common on lake-calving glaciers.

To learn more about Yakutat Glacier, read the Image of the Day we published on August 20, 2014. To learn more about the differences between lake-calving and tidewater glaciers, read this study published in the Journal of Glaciology.  And to see more photographs of Yakutat Glacier, check out Martin Truffer’s field dispatches on his Glacier Adventures blog. I’ve included one of my favorites—an aerial shot taken on September 26, 2011, after Yakut retreated enough that its single calving face had divided into two separate branches. The photograph was taken by William Dryer, one of Truffer’s colleagues.


Fish Stories from the ISS

August 19th, 2014 by Mike Carlowicz

Since he rocketed to the International Space Station (ISS) on May 29, 2014, American astronaut Reid Wiseman has been enjoying the sights. He has built an active following on Twitter by sharing photographs of a world he is seeing from space for the first time. Like many first-timers in space, he is also discovering some curiosities that most of us never see from the ground.

On August 18, he tweeted the following photo and comment: “Bangkok is the bright city. The green lights outside the city? No idea…”


Astute Twitter followers, journalists, and bloggers quickly pointed out that @astro_reid was most likely seeing fishing boats, which use bright lamps to draw plankton, squid, and fish to the surface. Several people even pointed to the Earth Observatory and our story about mysterious night lights off the coast of South America. It turns out that Wiseman’s fisherman also appear in the first three seconds of this time-lapse video shot from the ISS as it flew over eastern Asia in January 2014.

A few weeks ago, Wiseman had a similar experience looking out over Taiwan and the coast of China. “Could all those white lights off the coast of Taiwan be fishing boats? Hard to believe.”


Maybe Wiseman will spot some other strange lights, such as the mystery lights of the Australian Outback…the natural gas flares of the Dakotas…the contrail of a rocket…or gamma-ray rich lightning. The natural sights of the planet at night are far more compelling that any UFO stories.

More Melt Ponds

August 1st, 2014 by Adam Voiland



We published a photograph of a lone turquoise melt pond as our Image of the Day on August 2, 2014. Although that was one of the largest that scientists participating in the 2014 MABEL campaign saw, it certainly wasn’t the only one. In fact, that melt pond had plenty of companyand we had no shortage of photos of them.

The digital camera that captured the lone melt pond was taking a picture every 3 seconds, with each frame showing an area about 2.5 by 1.5 kilometers (1.6 by 0.9 miles). There were thousands of photographs to choose from, and many of them were spectacular. Above are two favorites. The upper image shows several narrow melt ponds and surface streams on a glacier in southeastern Alaska; the lower photo shows even more melt ponds on thinning sea ice.

Though melt ponds make for nice aerial photographs, they’re also a topic of great interest to scientists. In 2012, American researchers published an interesting study that detailed how melt ponds produce fractal patterns that can be useful for understanding the dynamics of sea ice melting. (For a more readable write-up, try this Scientific American blog post.) In 2014, scientists from the United Kingdom argued that the amount of water in spring melt ponds could be used to make skillful predictions about how much ice will melt during the height of summer.

A View to Remember

August 1st, 2014 by Adam Voiland

Over four missions, astronaut Carl Walz logged 231 days in space. Before the launch of the International Space Station resupply Orb-2 mission  from Wallops Island, Virginia, in July 2014, he described a few of views of Earth from space that he remembers best. Walz is now Vice President of Human Space Flight Operations at Orbital, a Virginia-based aerospace company.

“There was one rare, clear night that sticks out in my memory when I could see all the city lights along the Eastern Seaboard. I’ll never forget those lights. I could see New York, Philadelphia, Washington, all the way west to Chicago all at once. It was just all there…


…and there was absolutely nothing like flying over Las Vegas at night. You can actually see the colors of the lights. Most city lights are a kind of white light that’s a bit diffuse. Then there’s Las Vegas. It’s this bright spot out in the middle of the desert just staring you in the face…


…And the storms. We didn’t see any hurricanes because we were flying in the winter and springtime in the Northern Hemisphere, but we did see our share of thunderstorms. Remember, you’re looking at the thunderstorms from the top down. You can’t see lightning directly, but you can see these incredible flashes illuminating the clouds…



…Oh, of course, we’d sometimes see shooting stars. From that perspective, it was simply jaw-dropping.”


Editor’s Note: The photographs used to illustrate this post were not taken by Walz.  Click on each of image to find out more about when it was taken. To see more astronaut photographs, check the Earth Observatory Image of the Day on Mondays, browse the archive of astronaut photographs on Visible Earth, or search the Gateway to Astronaut Photography website.