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Just in case you’ve been living under a megalith, the internet’s abuzz over the discovery of a “circle” of stones on Mars.

Dubbed Marshenge, by commenter Jeff Taylor at Facebook’s Journey to the Surface of the MARS, this formation’s triggered a deluge of speculation. It was originally imaged by by the Mars Reconnaissance Orbiter on September 24, 2012 at 3:29 p.m. local time in Nilosyrtis Mensae (28.064°N, 75.956°E).


The obvious Earthly parallel is England’s Stonehenge. According to mainstream archaeologists this 5,000 year old stone circle is aligned with the summer solstice’s sunrise and the winter solstice’s sunset. Mavericks, like Graham Hancock, propose a connection between this and other megalithic sites across Earth, suggesting an ancient global civilization. This hypothesis isn’t so outlandish with Bronze Age burials around Stonehenge hailing from the Mediterranean, Germany, and France.

Were Martians among those cosmopolitan visitors, returning home to erect their own tourist trap? Until we have boots on the ground to “science the shit out of this” we won’t know for certain, but puny Earthlings can still make a pretty good guess.

Marshenge circle measurement

Marshenge hill measurement

The MRO’s HiRISE camera resolution in the original image is 25 cm per pixel.

This formation is impressive with Marshenge’s “hill” being approximately 359 pixels in diameter, and the stone “circle” is about 188 px, translating to 89.7 meters and 47 meters respectively. The four primary stones, which I shall provisionally dub Greg (3 o’clock), Patrick (6 o’clock), Andreas (9 o’clock), and Miguel (noon), cast shadows making it easy to calculate their height by plugging in the numbers from the NASA/University of Arizona’s metadata into the following equation.

tan (Sun Elevation)=(Height of the Object) / (Length of the shadow)

“Greg” is close to 2.25 meters tall, and “Miguel” a little shorter at 1.8m. “Patrick” is closer to 1.62m, and “Andreas” measures up to a mere 81 cm. These are short compared with the 7-9 meter tall megaliths of Stonehenge, but formidable with their remarkable width. “Greg”‘s 6.25 meters wide (measured at the diagonal, west to east), “Patrick” at 1.8m, “Miguel” 4m at the widest point, and “Andreas” measuring at 4.25m.

If their placement isn’t natural, then Martians certainly have a different aesthetic than us. The stones don’t appear to be aligned to cardinal directions nor the direction of Mars’s solstice sunrises and sunsets. Any resemblance to Stonehenge could be chalked up to pareidolia. Yet if this is an artificial arrangement, maybe there’s more to be found beneath the hill much like Göbekli Tepe appears to have been intentionally buried.

On the other hand, these stones might be ejecta from an ancient eruption. Another possible explanation, put forward by mainstream media, is ‘sorted terrain’, or ‘patterned ground’. This phenomenon appears on Earth and Mars where sediment and small stones are arranged by permafrost’s freeze-thaw cycles. Looking closely at the raw images, this may not be the case since the area doesn’t resemble Earth’s patterned ground below.

patterned ground and sorted terrain

Until humans can examine them firsthand, we’ll never know for certain. Until then, I’m fairly confident this is a natural phenomenon but hope to get proven wrong one day.

My gratitude to Andreas Müller at GreWi for his assistance in determining the correct pixel measurements, and utilizing HiRISE’s JP2 archives, facilitating my revision of this article with the correct dimensions of Marshenge.