Expert: Tom Whiting - 1/1/2012

Question
I have a general question Sir, I've read that our Solar system is headed towards the Leo constellation.  I understand that the earth spirals around the sun as the Sun heads towards Leo.  Meanwhile the whole galaxy is headed where?  Relative to all of this movement how is it that Polaris is relatively fixed in the sky.  With so many spirals and multidirectional spirals how does Polaris still seem to stay fixed?  Where or how can I understand it visually?
Thanks for your time and efforts.

Answer
Hi Adam,
You jumped one phase too many, of our true motion... by too much "skip" reading.  First, the Solar System is actually moving relative to the center of our Galaxy toward the star Vega, in Lyra.  (Actually it's more a spot near the Hercules/Vega border... that's why the Kepler spacecraft is attempting to find extra-solar planets in this region between Vega and Deneb).  It's our flight path, as it were, around the Milky Way Galaxy. (We know this is the "way" of the sun because the stars are slowly moving apart in that direction, whereas in exactly opposite direction in the sky, stars appear to be converging.) Just like in a plane the clouds ahead appear to be diverging, wheres the clouds behind you appear to be converging.
So the sun is actually moving toward the star Vega with the Earth and all the planets in a simple spiral motion following along with the sun.
Now the galaxy is moving around the Local Group (30 or so galaxies in a 5-10 million light year distance), AND THEN the Local Group (of galaxies) is moving around the great Virgo Supercluster of Galaxies out there some 65 million light years distant... And THAT is the motion in a direction toward the constellation of Leo. (So it's not just the Solar System, it's the WHOLE Local Group... of galaxies... moving toward Leo, in our orbit around the Virgo Supercluster core.

Polaris is simply one of our neighborhood stars (about 200 light years?) that our pole just happens to point to, right now. It is not fixed.  Thuban (Alpha Draconis) was our North Star when the pyramids were being built. 2012 years ago there was no North Star. Polaris will be closest to our north pole around 2105 AD. Then starting around 2500 AD there will be no North star for about 3000 years, until... I think it's Gamma Cephei is next in line. It's called precession of our polar axis, with a 25,800 year orbit, encompassing a 47 degree diameter (23.5 doubled) circle in our sky.
The bright star Vega will be our "North star" 13,000 years from now... and it was our North Star about 13,000 years ago, during the last Ice Age coming to an end.)
Remember 13,000 years is not very long, astronomically and geologically speaking.
But to answer your question, Polaris (and all the other stars in our neighborhood) seem to remain relatively "fixed" because of the vast distance to them, and the fact that all, or most,
of the neighborhood stars are all revolving pretty much together around the Milky Way Galaxy in nearly the same plane, taking 250 million years to make one orbit around the Galaxy, including Polaris (Alpha Ursae Minoris- it's other real name).
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA