Some features of this site are not compatible with your browser. Install Opera Mini to better experience this site.

Earth Matters

February Puzzler

February 24th, 2015 by Kathryn Hansen


Every month on Earth Matters, we offer a puzzling satellite image. The February 2015 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.

Good luck!

Flipped, Dirty, Amazing Icebergs

February 6th, 2015 by Adam Voiland

Photo © Alex Cornell.

Icebergs are white, right? Well, no, not completely. As seen in this shot (above) of a recently-flipped iceberg, their undersides can come in spectacular shades of blue and green. The photograph was captured in Cierva Cove, Antarctica, by videographer Alex Cornell during a family vacation. “[It] had this arresting alien-green color to it,” Cornell said of the iceberg in an interview with Universe Today. “It looked a lot more like a parked spacecraft than a floating iceberg.”

When icebergs look white, it is because compressed snow at their surfaces contain large numbers of tiny air bubbles and other reflective particles that tend to reflect all wavelengths of visible light equally. When ice gets compressed—such as when it is trapped under water—the air bubbles and other reflective particles get squeezed out and washed away, leaving purer ice behind. When light encounters pure ice, it can penetrate deep into it rather than reflecting off the surface. As light moves through ice, longer wavelengths (red and yellow) tend to be absorbed most readily, leaving shorter-wavelength green and blue light to reflect back. This “leftover” blue and green light is what gives the undersides of icebergs their remarkable color.

As impressive as it is to see a close-up view, spotting blue ice is not that uncommon. In 2012, we published an aerial photograph with a striking patch of blue ice. Blue ice also shows up regularly in satellite imagery, such as this image acquired by the Advanced Land Imager on EO-1 in 2011.


To learn more about the color of icebergs, check out these stories from WebExhibits, the National Snow & Ice Data Center, and Seed. PetaPixel has also published an interesting guest blog post in which Cornell explains how he produced and distributed the photographs from start to finish. You can find more shots of the flipped berg on his website and Instagram page.

Cornell’s images were not the only jaw-dropping iceberg photographs I noticed this week. On Tuesday, Antarctic Sun editor Peter Rejcek pointed out that the U.S. Antarctic Program had added several new iceberg photographs to their photo library. The images below show an overturned iceberg (with some penguins on top) that contains centuries of windblown sediments and minerals. It really is the stuff of dreams.


Photograph by Ethan Norris, National Science Foundation.


Photograph By: Ethan Norris, National Science Foundation



January Puzzler Answer: Arrecife Alacranes

February 5th, 2015 by Kathryn Hansen



The January 2015 puzzler (top image) might look like bacteria in a petri dish—many guesses played off some variation of that theme. However, if you answered “coral reef,” you were on the right track.

Alexandre Mathieu was the fist to submit a comment to our Earth Matters blog suggesting that the image was a reef. There were also some good guesses on Facebook, such as this post (and poem!) from Clinton Rivers:

This looks like a coral reef
Like Great Barrier or perhaps Belize

A sign from space Of co-operation! 
Down below in the coral nation

Polyps grow and work together 
With a tiny algae called zooxanthellae

Their carbon capture is solar powered 
In warm waters you may see their towers 

Together they can build a home
Lots of them a reef or dome

An example for us fresh from the ocean 
To live on this earth in Symbiosis

The puzzler, however, proved too obscure for anyone to correctly identify the reef’s location. The puzzle image showed the middle portion of Arrecife Alacranes (bottom image)—a reef in the southern Gulf of Mexico, about 100 kilometers (60 miles) north of Progresso, Mexico. Read the Image of the Day caption to learn more.

It’s rare for a puzzler to stump all of our savvy readers. That’s not our goal, but it’s a fine line between images that are too easy and too hard. Had we cropped the image to include any of the five small islands in the area, we would likely have been flooded with correct answers almost immediately! Tune in next month for a puzzler that will likely be a bit more identifiable.