NASA Mars imagery captures auroras covering planet

"Mars is experiencing its greatest level of auroral activity in the past 10 years," Nick Schneider of the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP), told spaceweather.com. "In February alone, there were three episodes of global auroras, an 'aurora hat trick' we've never seen before."

Auroras are triggered by coronal mass ejections or CMEs, which are large plumes of solar plasma spat out from the sun. When this reaches the Earth, it triggers a geomagnetic storm, where these charged particles from the sun are funneled by the Earth's magnetic field toward the poles. The ions then collide with gas molecules such as oxygen and nitrogen, exciting the atmospheric molecules.

"These excited particles glow. The type of particle being hit (oxygen, nitrogen, etc) determines the color of the auroral glow," Delores Knipp, a space weather research professor at the University of Colorado Boulder, told Newsweek.

Unlike Earth, which is surrounded by a continuous global magnetic field, Mars has several localized, umbrella-shaped magnetic fields that emerge sporadically from the surface, predominantly in the southern hemisphere. These are thought to be the remains of an ancient global magnetic field that deteriorated billions of years ago.

"Mars has no global magnetic field, like the drawings of a magnet lined up with Earth's poles. Magnetic fields are made deep in the molten metal cores of planets as they spin and churn. Mars is much smaller than Earth, so its interior has already cooled off and it can't create a magnetic field," Schneider told Newsweek.

Therefore, Mars's aurorae aren't limited to only its poles, and can be seen across the whole planet.

"Earth's strong magnetic field protects the planet when violent solar activity blasts energetic particles through the solar system. But Mars lacks that protective "bubble," so those energetic particles bombard the planet everywhere. The whole night sky lights up, especially at the current level of activity at "Solar Max." Some particles can penetrate the atmosphere so deeply is could be a hazard to future astronauts," Schneider said.

The MAVEN images show a purple false-color version of the aurora's ultraviolet components. MAVEN cannot pick up visible light, but the aurorae likely were detectable in the visible light spectrum too.

"We can confidently predict that Mars aurora will glow green, based on extensive studies the aurora at ultraviolet wavelengths by the MAVEN spacecraft. There's just enough atomic oxygen at the top of Mars' atmosphere to appear the same color as green aurora on Earth. No camera sent to Mars so far has adequate "nighttime settings," but we're working to get better cameras on future missions—a smartphone camera would work well enough!" Schneider explained.

"The aurora will be plenty bright for future astronauts to watch, as long as it's safe to do so."

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