Displays of colorful lights known as aurora occur on Mars, scientists announced today.
Terrestrial auroral displays, known also as the Northern Lights in the Northern Hemisphere, wow skywatchers routinely in parts of the far North. The glowing shows occasionally dip as far south as Texas when solar activity peaks.
Auroras are created when charged particles from the Sun interact with molecules and atoms in the atmosphere, creating a glow similar to neon lighting in terms of the science involved. The solar particles are funneled toward polar regions by Earth's strong magnetic field. Seen from space, the lights create bright rings around the poles. Each auroral oval is about 1,860 miles (3,000 kilometers) in diameter.
The phenomenon on Mars is created in the same manner. But Mars has a much thinner atmosphere and only weak magnetic fields, its internal dynamo having died out long ago. Remnants of martian magnetism exist in pockets of rock, and that's where the new study focused.
"We have discovered the aurora exactly at the place of maximal magnetic field on the surface of Mars, as recorded previously by NASA Mars Global Surveyor," said study leader Jean-Loup Bertaux of Service from Aeronomie at the CNRS in France. "It is small in horizontal extent, about [19 miles] 30 kilometers."
Unlike Earth's mix of colors, which often bathe the sky in reds and greens, auroras on Mars would likely be faint and blue if seen by an astronaut on the surface, Bertaux told SPACE.com.
"He would see a pillar of light, as on Earth, but possibly weaker," Bertaux said.
The observations were made with the European Space Agency's orbiting Mars Express satellite. No conventional images were produced. The findings are detailed in the June 9 issue of the journal Nature.
Previous studies have found auroral displays on Saturn, Jupiter. On those planets, the process is affected by magnetic activity similar to the earthly variety.
Aurora from the Space Station