It’s called the red planet for a reason. So just what are these large blue patches dotting the surface of Mars?
Is it a shallow lake that we’re seeing? An odd, one-off chemical reaction? A flash frozen patch of ice from a begone era? Nope, what we’re seeing is not water, chemistry, or cold temperatures: It’s wind. Or, more accurately, the evidence of incredibly strong windstorms past — and the Martian volcanoes they once swept by.
The ESA, who just released the photo, explains that what we’re seeing is actually the effect of a dust storm, or perhaps several — with winds just shy of an Earth-bound Category 1 hurricane — extending over the course of up to many weeks.
Some of the dust that gets swept up is from Mars’ volcanoes, and as it moves, small layers of this darker dust get trapped in the craters pockmarking the landscape. Over time, enough of the volcanic dust collected to darken the surface and show up as the blue patches we’re seeing now.
To get a better idea of just how it works, check out this picture of the effects of a much younger wind storm blowing volcanic dust and ash into a Martian crater. The color itself may be a little less dramatic, but looking at just how far the winds scattered the dust makes it pretty clear that the wind storms on Mars are not to be trifled with:
Images: ESA/DLR/FU Berlin.