The planet Earth has Polaris as its Polestar, meaning that the
apparent location of Polaris in the sky places it directly over one of
Earth's physical Poles (the North Pole in our case). Does the planet
Mars have a Polestar as well? If so, which Star is it, and above which
Pole does it ride?

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Request for Question Clarification by sublime1-ga on 07 May 2006 15:10 PDT

grandrascal...

Mars' north pole view can be seen here:
http://www.eknent.com/etc/mars_np.png

...and the south pole view is here:
http://www.eknent.com/etc/mars_sp.png

As you can see, there's no easily visible star which would
serve as a useful pole star.

The following discussion on this topic, on the Bad Astronomy
and Universe Today Forum may interest you:
http://www.bautforum.com/archive/index.php/t-38314.html

Let me know if this satisfies your interests...

sublime1-ga

---

Clarification of Question by grandrascal-ga on 11 May 2006 01:44 PDT

I Asked:
.>> Does the planet Mars have a Polestar...? If so, which Star
 >> is it, and above which Pole does it ride?

You Respond:
.> ...As you can see, there's no easily visible star which would
 > serve as a useful polestar.

I Reply:

Then your answer to, "Does the planet Mars have a Polestar?" is
"No, it doesn't" -- a perfectly valid answer, especially if it
is true! Post it, and I'll accept it.   :)

grandrascal...

Thanks for confirming my response as an acceptable answer.
I'll repost it here for the sake of future readers.

---------------------------------------------------------

Mars' north pole view can be seen here:
http://www.eknent.com/etc/mars_np.png

...and the south pole view is here:
http://www.eknent.com/etc/mars_sp.png

As you can see, there's no easily visible star which would
serve as a useful pole star.

The following discussion on this topic, on the Bad Astronomy
and Universe Today Forum may interest you:
http://www.bautforum.com/archive/index.php/t-38314.html

sublime1-ga


Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.

Searches done, via Google:

mars polestar
://www.google.com/search?q=mars+polestar

Thanks for a fast answer. Sorry if I was a bit late responding -- I
wasn't online for a day or so.

Nor has the Earth always had a good pole star. The north celestial
pole precesses in a circle with a radius of 23 degrees every 26,000
years. When Confucius wrote about the constancy of the pole star, he
was talking about a completely different star.

.> When Confucius wrote about the constancy of the pole star, he
 > was talking about a completely different star.

Interesting! I already knew about the Earth's precession, of course.
Just out of errant curiosity, you wouldn't happen to know which star
Confucius knew as the Polestar away back then, would you...?

Good question. I don't know the answer. The last bright star that was
close to North was Thuban, or Alpha Draconis, the brightest star in
the constellation Draco the Dragon. Thuban was the pole star during
the construction of the pyramid of Khufu and was closest to North
around 2000 BC, well before Confucius (~500 BC). There was not a
comparably bright star close to North at the time of Confucius. Good
thing there was not as much light pollution in those days!

Actually in 2000 years the difference would probably not be that
great, so Confucious probably knew the same polestar we do.

http://tinyurl.com/g74fs

"Thuban was the North Star 4,800 years ago at the time of the 'Old
Kingdom' in Egypt---a period when most of the pyramids were built,"
Teske said. "The exact pole has crept from Thuban to its present
position near Polaris and now is headed toward gamma Cephei, which
will be the North Star in about 2,000 years.

Another article stated the pole currently points about 4 degrees from polaris. 
So it seems we're already headed away from Polaris, although I don't
know when it was at it's closest to being lined up with the pole.
Thuban is 26 degrees from polaris, a rough calc would show that
Polaris would have been about 10
 degrees further from the pole 2000 years ago, or about 2-3 times the
current distance.

Almundy,

Polaris has a declination of 89.25 degrees, so it is 0.75 degrees from
the pole, not 4 degrees, which would be very noticeable, since it
would trace a circle whose diameter was 16 times the diameter of the
moon.

At the time of Confucius (2500 years ago) the pole was closer to
Thuban than to Polaris. This is a huge distance and I cannot imagine
that either Thuban or Polaris would be considered a pole star at that
time. A better candidate is Kochab in Ursa Minor, which was considered
to be the pole star at the time of Homer (~800 BC). See, for example:

http://www.astro.uiuc.edu/~kaler/sow/thuban.html

grandrascal...

Thanks very much for the rating and the tip!

sublime1-ga

Actually,

Mars does have a pole star, it's just very faint and it's an unnamed
star, known only by it's numeric designations.  The North Star for
Mars is HIP 104516, or HD 201834.  From Mar's North Pole, it would
have an aparent magnitude of 5.75, which would be barely visible to
the naked eye.  In the South, there is again a polar star, but it is
far too faint to see with the naked eye, having a app-mag of greater
than 8.00.  The closest easily visible star near the sout pole is
Kappa Vela (HIP=45941, HD=81188).  It has an app-mag of 2.5, so it is
fairly bright, and it is just a degree or two off perfect polar
orientation.