Celestial navigation plus accurate clocks. I'd think this would be especially good on a planet without clouds (as long as your planet rotates fast enough, so I guess Mercury is out). Anyone know if Mars has any polar stars?
[source pg 4] https://www-robotics.jpl.nasa.gov/publications/Reg_Willson/M...
"The attitude of the rover is based on measurements from two vector instruments: (1) accelerometers that determine the vector towards the center of gravity of Mars and (2) Pancam solar images that determine the vector to the Sun."
Because you generally only need the brightest subset of stars in any area, you don't even need a comprehensive one.
A star map for Mars would functionally be pretty much equivalent to an earth one, I guess, given the distances involved.
So the dark side of mercury would work fine. On the hot side as long as you are not exactly on the equator the sun acts as a fixed direction and you can use that.
> Anyone know if Mars has any polar stars?
The orbital tilt of Mars is 1.85 degrees (vs 0 for earth) and the Axial tilt is 25.19 vs 23.44 for Earth. So Polaris would be pretty close to being a polar star for Mars as well.
Still the thought of seeing literally the same stars on an alien world is blowing my mind. Just imagine the same sky, but different planet... wow
Objects inside of our own solar system, on the other hand, would be really interesting to look at through such a setup.
It depends on how the two tilts interact - do they cancel or add? I don't know.
ISTM this would work on the equator too?
If you can figure out where the sun is, and you know what time it is, you're in good shape.
If you are on the equator, but not directly under the sun then you can figure things out.
I guess I should have said equator on the central meridian.
Edit: I was under the mistaken assumption that Mercury is tidally locked.
So it would sort of work on the equator as well, but you might have to wait a bit for the sun to move enough to tell where you are.
Poris is only useful if you're in the northern hemisphere. In the southern hemisphere on earth we use the southern cross. It's a bit trickier if you're using a quadrant because you have to align it with a blank area of sky. Though the 17th century explorers managed it.
http://abaaonline.blogspot.com/2013/07/pole-star-on-differen...
Mars north pole points near Deneb. The reference also gives pole stars for other planets.
They're pretty much all cirrus-equivalents, granted, but they're still water (more precisely, water ice) clouds. That is, unless NASA is misinterpreting them, but seeing as they're, like, the end-all-be-all experts on Martian climate, I reckon that's unlikely.
Even barring that, however, dust clouds would also cause issues for celestial navigation.