Gemini streamers

Six stars look like one in Gemini: together they form Castor. The naked eye sees a single point. Pollux is brighter, despite Castor's "Alpha" label, because Johann Bayer did not carefully distinguish the pair in 1603. The names come from the twins of Greek myth, sons of Leda who both sailed with the Argonauts. Pollux was the son of Zeus; Castor was mortal. Their twin symbol belongs to the mutable air sign ruled by Mercury, with dates of May 21 to June 20. Gemini also appears in two discovery stories. William Herschel discovered Uranus here in 1781, and Clyde Tombaugh found Pluto on plates centered on a Gemini star in 1930.