At first look, an image captured by NASA's Mars Reconnaissance Orbiter seems to feature spider-like objects crawling over the surface of Mars. The image, which was clicked on 13 May 2018 and released on Friday, actually shows a unique phenomenon that has little to do with spiders.
The picture shows a carbon dioxide ice cap covering a region on the Red Planet and as the sun returns in the spring, the "spiders" appear to emerge from the landscape.
The phenomenon, which happens when CO2 below Mars' surface warms in the spring and changes from solid to gas, leads to spider-like radiating mounds on the surface and is called "araneiform terrain".
"The word 'araneiform' means 'spider-like'. There are radially organised channels on Mars that look spider-like, but we don't want to confuse anyone by talking about 'spiders' when we really mean 'channels,' not bugs," NASA said.
"Over time, the trapped carbon dioxide gas builds in pressure and is eventually strong enough to break through the ice as a jet that erupts dust. The gas is released into the atmosphere and darker dust may be deposited around the vent or transported by winds to produce streaks. The loss of the sublimated carbon dioxide leaves behind these spider-like features etched into the surface," a NASA release said.
This >active seasonal process, however, is not seen on Earth, NASA said, while comparing the process to the sublimation of dry ice on Earth.