Arcturus has the largest "proper motion" -- motion across the sky -- of any of the bright stars except Alpha Centauri, the nearest star to our solar system. In 100 years Arcturus moves across the sky a distance equal to about half the width of your little finger held at arm's length.
At its distance of nearly 37 light years, this motion, when combined with its motion along our line of sight measured spectroscopically using the Doppler shift, yields a space velocity of about 76 miles per second with respect to our Sun. Most stars in our vicinity are moving relatively slowly with respect to Sol because of our common motion carrying us around the center of the Milky Way galaxy every 250 million years. Arcturus is in an elongated orbit around the Galaxy's center that carries it out into the Galaxy's halo.
It was famous with the seamenof early days and as a calender sign regulated their annual festival by its movements in relation to the sun. But its influence always was dreaded, as is seen in Aratos writings.
Polaris
