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Mars Crater or Collapse? A Photo Mystery in Martian 'Swiss Cheese'

dimple on mars, south polar pit, crater
This photo from NASA's Mars Reconnaissance Orbiter shows a crater or pit in the planet's southern hemisphere, where it is currently summer. Carbon dioxide ice gives the region a "swiss cheese" look in this view released June 2, 2017. (Image credit: NASA/JPL-Caltech/University of Arizona)

Scientists aren't sure if a big dimple on Mars came from something smacking into the Red Planet's surface or if was simply caused by a collapse.

A new image from NASA's Mars Reconnaissance Orbiter (MRO) shows several shallow pits among carbon dioxide ice, nicknamed "Swiss cheese terrain" because it looks a bit like the famous cheese.

But at upper right is a deeper pit that goes through the ice and dust, which NASA says could be an impact crater or some sort of collapse pit. [See more amazing Mars photos by MRO]

The picture was taken in the southern hemisphere of Mars late in the summer and unveiled Friday (June 2). At the time the image was taken, the sun was low in the Martian sky and the shadows it cast allowed for more "subtle" topography to show in the image, NASA officials.

MRO takes detailed pictures of the surface using the University of Arizona's High Resolution Imaging Science Experiment (HiRISE) camera. The spacecraft launched in 2005 and has been orbiting Mars since 2006.

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Elizabeth Howell, Ph.D., is a contributing writer for (opens in new tab) since 2012. As a proud Trekkie and Canadian, she tackles topics like spaceflight, diversity, science fiction, astronomy and gaming to help others explore the universe. Elizabeth's on-site reporting includes two human spaceflight launches from Kazakhstan, and embedded reporting from a simulated Mars mission in Utah. She holds a Ph.D. and M.Sc (opens in new tab). in Space Studies from the University of North Dakota, and a Bachelor of Journalism from Canada's Carleton University. Her latest book, NASA Leadership Moments, is co-written with astronaut Dave Williams. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday.