A mystery is brewing on Mars: Amateur astronomers spotted enormous plumes erupting off the Red Planet's surface, leaving scientists puzzled.
More than 155 miles (250 kilometers) high and hundreds of miles across, the baffling plumes were spotted by amateur astronomers in the spring of 2012. The plumes reflect sunlight, which means they could be made of water ice, carbon dioxide ice or dust. But clouds made of those materials would be hard to explain with current models of the Martian atmosphere, scientists say.
Images of Mars from the last 20 years reveal that shorter plumes, reaching heights of about 62 miles (100 km), occasionally flare up from the planet's surface. An image by the Hubble Space Telescope from 1997 revealed another abnormally high plume, similar to the one seen in 2012, according to a statement from the European Space Agency (ESA). [7 Biggest Mysteries On Mars]
Scientists at the Universidad del Pais Vasco in Spain studied the images of the plumes and confirmed that they reach heights of more than 155 miles (250 km) above the surface, and cover an area of up to 310 by 620 miles (500 by 1,000 km).
"At about 250 km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected," says Agustín Sánchez-Lavega of the Universidad del País Vasco, lead author of the new research.
The features developed in less than 10 hours and remained visible for about 10 days, but changed their structure from day to day, ESA officials wrote in a statement. None of the spacecraft orbiting Mars were in a position to see the plumes, due to their locations around the planet and light conditions at the time.
Analysis of the images from 2012 and of past images of plumes erupting from the surface of Mars haven't helped the researchers determine what caused the plumes or what they are made of.
The ESA statement reports that "further insights should be possible following the arrival of ESA's ExoMars Trace Gas Orbiter at the Red Planet, scheduled for launch in 2016."
The new results were reported in Monday's (Feb. 16) issue of the journal Nature.