Giant plumes of haze that had mysteriously appeared and later vanished high above the surface of Mars have baffled scientists.
The first plume was spotted in March 2012, the next in April 2012, reaching more than 250km above the surface of the Red Planet.
The haze has been described as highly “unusual.” Usually, the highest clouds on Mars reach around 100km, said study co-author Antonio Garcia Munoz, a planetary scientist with the European Space Agency’s European Space Research and Technology Centre in the Netherlands.
“It’s quite shocking that this is happening at a 200-kilometer altitude,” Garcia Munoz told the Los Angeles Times. “This is completely unusual.”
Two main explanations have been posed by researchers, with one being that the plumes could be “caused by a cloud of carbon dioxide ice or water ice particles.”
However, the phenomenon “could also be caused by an aurora, rather like the one responsible for the northern lights on Earth,” the newspaper reported.
“Both tentative explanations have pros and cons,” he added, “and the final conclusion is that we are not so sure what is causing this plume.”
Adding to the mystery, the plumes were described as extremely broad, stretching across an area measuring roughly 1,000km by 500km and lasted about 10 days each time.