Every month on Earth Matters, we offer a puzzling satellite image. The August 2018 puzzler is above. Your challenge is to use the comments section to tell us what we are looking at and why this place is interesting.
How to answer. You can use a few words or several paragraphs. You might simply tell us the location. 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 feature in the image. If you think something is interesting or noteworthy, tell us about it.
The prize. We can’t offer prize money or a trip to Mars, 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. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have shaped the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.
Recent winners. If you’ve won the puzzler in the past few months or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance to play.
Releasing Comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance to play, we may wait between 24 to 48 hours before posting comments.
Answer: About two billion years ago, an asteroid hit Earth southwest of what is now Johannesburg, South Africa, and formed Vredefort Crater—the world’s oldest and largest known impact structure. Layers of upturned rock eroded at different rates and produced the concentric pattern visible in the image above. Congratulations to Felix Bossert and Tom for correctly identifying the feature. Read more about the image in our September 1, 2018, Image of the Day.