Mysterious Plumes on Mars May Be Extraterrestrial Auroras
Amateur astronomers have reported sightings of strange, plume-like features on Mars on two separate occasions in 2012, and ESA scientists have no idea what to make of them. They were seen in the same region in both instances, approximately 250 km above the surface of the Red Planet.
"At about 250 km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected," said lead author Agustin Sanchez-Lavega. The plumes extended for 500-1,000 km and lasted for approximately ten days. They only appeared on the morning side of the Martian terminator, which is a moving line that separates the light and dark sides of a planetary body, which shows that the plumes evolve rapidly over ten hours and demonstrate cyclical behavior. They also showed variability, or changes in appearance and structure, from day to day.
As a result of a magnetic anomaly in the region where the plumes were observed, ESA scientists believe that the strange phenomena could be Martian auroras. "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," said co-author Antonio Garcia Munoz. If this theory is correct, then this auroral emission would be 1,000 times as bright as Earth's observed auroras.
The other predominant theory is that the plume represents "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," said Sanchez-Lavega.
The origins of these plumes are still unknown, although ESA expects to have more information about the mysterious structures when their ExoMars Trace Gas Orbiter arrives on the Red Planet in 2016.