Scientists baffled by mysterious haze on Mars
There's a big mystery floating on Mars: A giant haze that was first spotted in 2012 has reappeared and scientists still don't know how to explain it.
According to the journal Nature, the plume stretches more than 600 miles. Researchers say it's the largest they've ever seen on the Red Planet.
Despite its grand size, they still don't know what it is or how it got to the upper reaches of the atmosphere.
Scientists believe it could be a bright aurora, similar to the northern lights ... or a large cloud of carbon dioxide or water particles.
A planetary scientist from the European Space Agency told the BBC, "We know there are clouds on Mars, but clouds, up to this point, have been observed up to an altitude of 100km...And we are reporting a plume at 200km, so it is significantly different. At 200km, we shouldn't see any clouds, the atmosphere is too thin..."
He also says if any of the theories are correct, "it would mean our understanding of Mars' upper atmosphere is wrong."
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