|The MAVEN Mars probe has detected widespread green |
auroras on Mars (even though this NASA artist's
conception shows them as violet). (NASA image)
Mars does not have a magnetic field surrounding the whole planet as Earth does, but rather sporadic "magnetic umbrellas" that are remnants of an ancient global field, and they are regularly "lit up" by particles from the sun. But according to researchers at the University of Colorado, which operates MAVEN's Imaging Ultraviolet Spectrograph (IUVS) instrument, these umbrellas are mostly found in Mars's southern hemisphere and there is now evidence of widespread auroras in the northern hemisphere as well.
"The (solar) particles seem to precipitate into the atmosphere anywhere they want," says IUVS lead scientist Nick Schneider. "Magnetic fields in the solar wind drape across Mars … and the charged particles just follow those field lines down into the atmosphere."