Just like on Earth, the end of northern summer sees an atmospheric vortex develop over Mars’ north pole and last through to the spring. On Earth the polar vortex can sometimes become unstable, lose its shape and descend southwards, bringing colder weather to the mid-latitudes. The same can happen to Mars’ polar vortex, and in doing so it provides an opportunity to probe its interior. “Because winters at Mars’ north pole experience total darkness, like on Earth, they are very hard to study,” Dr. Olsen said. What goes on inside the Mars north polar vortex?