Martian North Star

The North Star serves as a guidepost for people living on Earth’s northern hemisphere. “Does the planet Mars have a North Star?”

There happens to be a star now over the northern axis of the Earth. We call that star Polaris, or the North Star. But the identity of Earth’s North Star changes over time, due to the precession of the Earth. Precession causes Earth’s axis to trace out a circle among the stars. One cycle of precession takes 26,000 years. So the star we call Polaris hasn’t always been the North Star. There’ve been many North Stars for Earth.

The north pole of Mars today points at a dim, nameless star, difficult to glimpse through the dusty martian atmosphere. This present-day martian North Star lies in the star figure we earthlings call Cygnus the Swan. But, like Earth, Mars also undergoes a cycle of precession. It completes one cycle in 180,000 years. because of its precession, Mars, like Earth, has the potential to have many different North Stars over time. Still, it’s not possible to say for certain where Mars’ northern axis pointed in the past or will point in the future.

That’s because unlike Earth, Mars lacks a large, stabilizing moon. So its seasonal tilt undergoes chaotic shifts.

Article for inspiration:

  • “Long-Term Orbital and Spin Dynamics of Mars,” William R. Ward, in Mars, Hugh H. Kieffer, et al., editors, University of Arizona Press, 1992.

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