As a photographer, one of the targets on my bucket list is the Northern Lights. As the Sun ramps up into a solar maximum, the chance of the aurorae reaching where I live is increasing, so that’s good. More solar activity means more aurorae, which are, all told, pretty common here on Earth. But today I learned that there are also aurorae on Mars.

Which doesn’t make sense to me as Mars doesn’t have a global magnetic field as Earth does. Still, NASA’s MAVEN spacecraft has observed over 200 so-called ‘discrete’ aurorae which only occur in the southern hemisphere of the red planet. And physicists have analyzed those observations and discovered that the solar wind – which causes aurorae on Earth – is interacting with localized bits of crustal magnetic fields to create those discrete aurorae.

Co-author Zachary Girazian explains: Our main finding is that inside the strong crustal field region, the aurora occurrence rate depends mostly on the orientation of the solar wind magnetic field, while outside the strong crustal field region, the occurrence rate depends mostly on the solar wind dynamic pressure.

So while Mars doesn’t have a global magnetic field, there are enough magnetic field generating regions in the southern hemisphere to interact with the solar wind. And now you know.

More Information

University of Iowa press release

“Discrete Aurora at Mars: Dependence on Upstream Solar Wind Conditions,” Z. Girazian et al., 2022 March 27, JPR Space Physics