Page:Star Lore Of All Ages, 1911.pdf/501

Rh for a time after the capture of Constantinople. In Damascus it was called "Mismār," a "needle" or "nail."

Other titles for the Pole Star are "the Chariot Star," "the Steering Star," "the Lodestar," "the Northern Axle" or "Spindle."

It is generally supposed that the North Star marks the true Pole of the earth, but in reality it is 1° 14′ distant from the true Pole. Its mean right ascension, as given by the Harvard Observatory List of Bright Stars, is 1 h 22.6 m., consequently when the right ascension of the meridian of any place is the same, Polaris will be exactly on the meridian at that time and place, but above or below the true Pole. The approximate location of the true Pole may be found by drawing an imaginary line from Polaris to ζ Ursæ Majoris. The Pole is on this line in the direction of ζ at a distance from Polaris equal to about one fourth of the distance between the Pointer stars of the Dipper.

Polaris revolves around the true Pole once in twenty-four hours in a little circle 2.5° in diameter. Within this circle two hundred stars have been photographed. "Polaris will continue its gradual approach to the Pole till about the year 2095, when it will be only 26′ 30″ away from it. It will then recede," according to Allen, "in favour successively of γ, π, ζ, ν, and α, Cephei, and α, and δ, Cygni, and α Lyæe, Vega, when, marked by this last brilliant star 11,500 years hence, the Pole will beabout fifty degrees distant from its present position and within five degrees of Vega, which for 3000 years will serve as the Pole Star of the then existing races of mankind. The Polar point will then circle past ι and τ Herculis, θ, ι, and α, Draconis, β, Ursæ Majoris, and κ, Draconis back to our Polaris again, the entire period being from 25,695 to 25,868 years according to different calculations." See accompanying diagram.

Polaris is from thirty-six to sixty-three light years distant from the earth, and is receding from our system at the rate