This month look for the star Rasalhague in the constellation of Ophiuchus the Serpent Bearer. Rasalhague is the brightest star of this large and dim constellation, which has the shape of a simple house and reaches nearly to the zenith. Ophiuchus is located in the south, just above Scorpius on August evenings and Rasalhague is the star at the top of the constellation.

In Greek myth, Ophiuchus is Asclepius the healer. He was born to a mortal mother and his father was the Greek god Apollo. In his youth, Asclepius was given to Chiron the centaur to raise. It was Chiron who trained his adopted son to be healer. Asclepius became such a great healer that he brought several of his dead patients back to life. To prevent him from going too far, Zeus hurled a thunderbolt and killed Asclepius. His father Apollo complained about the death of his son, so Zeus made Asclepius immortal and placed him in the sky as Ophiuchus.    

Rasalhague (also called Alpha Ophiuchi and 55 Ophiuchi) is Arabic for "the Head of the Serpent Collector."  The star is 47 light years away. Therefore, the light you see from Rasalhague tonight left in 1966. Rasalhague is a double star, but its companion is so close that even a telescope can’t resolve them as separate stars. Rasalhague is spectral type A5 (white in color) and has a surface temperature of 18,000 degrees (compare to 5,800 degrees for the sun). That makes Rasalhague twice as hot and 25 times brighter than our sun. Rasalhague recently (in stellar years) stopped converting hydrogen into helium. Its higher core temperature is permitting the star to generate energy by fusing the helium ash in its core into carbon and oxygen.