NASA has announced a pair of unusual findings made by its MAVEN mission, which is meant to sample Mars' atmosphere in order to help us understand its evolution. But, by orbiting through the outer edges of the atmosphere, the mission has identified some unexpected features of the area above the red planet.

The first, and easiest to understand, is the auroras. Dubbed the "Christmas Lights" because of their appearance in December of last year, the glow was in the ultraviolet range and spanned the entire Northern Hemisphere of Mars. The source of the energy was electrons accelerated out from the Sun, which were detected by another instrument on MAVEN. Because Mars lacks a magnetic field, the electrons also made it deep into the atmosphere, producing a light show that was close to the surface relative to Earth's auroras.

The dust, however, is not as easy to explain. It's been a constant, present since MAVEN first entered orbit, and ranges between 150 and 300km above the surface, with the density of particles increasing at lower altitudes. Much like the recent dust plume observed above the planet, it's not clear what could be lofting the particles from Mars' surface. "If the dust originates from the atmosphere, this suggests we are missing some fundamental process in the Martian atmosphere," said Laila Andersson of the University of Colorado.

Alternative explanations involve a non-Martian source, such as debris from comets or even Mars' two small moons. There's also the possibility that it, too, could be a solar phenomenon.

MAVEN is only four months into its mission, so the red planet may have other surprises in store for its operators.