Strange clouds that have been spotted twice hovering over Mars have scientists baffled.
In March and April of 2012 amateur astronomers reported "plume-like features" developing on the Red Planet, the European Space Agency (ESA) reported. These plumes were seen rising over 150 feet above the same region of Mars in both puzzling sightings.
"At about [155 miles], the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected," said Agustin Sanchez-Lavega of the Universidad del País Vasco in Spain, lead author of the paper reporting the results in the journal Nature.
The strange features developed in less than 10 hours and lasted for about 10 days before disappearing; their structures were observed to continually change throughout the time they were visible. Following the sightings researchers looked back on archived Hubble Space Telescope images taken between 1995 and 1999 as well as amateur images taken between 2001 and 2014. They identified an unusually high plume similar to what was seen recently in a Hubble images from May 17 1997. The researchers are now using Hubble data to try to gain insight into what is causing the elusive haze.
"One idea we've discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes," Agustin said.
"Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field," added Antonio Garcia Munoz, a research fellow at ESA's ESTEC and co-author of the study.
