CORONA BOREALIS (kō-rō´nä bō-rē-a´-lis)--THE NORTHERN CROWN.
LOCATION.--A line drawn from α Cygni, to α Lyræ, and projected a little over 40°, terminates in the Crown, which lies between Hercules and Boötes, and just above the diamond-shaped group of stars in the head of the Serpent.
The characteristic semicircle resembling a crown is easily traced out. The principal stars are of the fourth magnitude excepting Gemma, which is a second-magnitude star and known as the "Pearl of the Crown."
Gemma, sometimes called Alphacca, forms with the stars Seginus and Arcturus, in Boötes, an isosceles triangle, the vertex of which is at Arcturus.
Close to ε a famous temporary appeared suddenly May 12, 1866, as a second-magnitude star. It was known as the "Blaze Star" and was visible to the naked eye only eight days, fading at that time to a tenth-magnitude star, and then rising to an eighth-magnitude, where it still remains.
The native Australians called this constellation "The Boomerang." To the Hebrews it was "Ataroth" and by this name it is known in the East to-day. No two of the seven stars composing the Crown are moving in the same direction or at the same rate.
α Coronæ is seventy-eight light years distant and sixty times brighter than the sun.
LOCATION.--A line drawn from either Vega, in Lyra, or Altair, in Aquila, to Gemma, in Corona Borealis, passes through this constellation. The left foot of Hercules rests on the head of Draco, on the north, and his head nearly touches the head of Ophiuchus on the south.
The star in the head of Hercules, Ras Algethi, is about 25° southeast of Corona Borealis.
α Ophiuchi and α Herculis are only about 5° apart.
The cluster 13 M., the Halley Nebula, can be easily seen in an opera-glass. In a recent photograph of this cluster 50,000 stars are shown in an area of sky which would be entirely covered by the full moon.
Hercules occupies the part of the heavens toward which the sun is bearing the earth and planets at the rate of twelve miles a second or 373 million miles a year.
On a clear night the asterism Cerberus, the three-headed dog, which Hercules holds in his hand, can be seen.
This constellation is said to have been an object of worship in Phœnicia. There is a good deal of mystery about its origin. The ancient Greeks called it "The Phantom" and "The Man upon his Knees."