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The strong man and the snake handler go head to head on spring and summer nights.
Rasalhague is the star that represents the head of Ophiuchus, the serpent bearer. And Rasalgethi is the head of Hercules, the strong man. Rasalhague climbs into good view in the east by around 10:30, with fainter Rasalgethi above it. They’re separated by only about five degrees — the width of three fingers held at arm’s length.
The names of the two stars come from ancient Arabic. The first part of each name, Ras, means “head.” And these aren’t the only stars named for the head of a constellation. Another is Rastaban — the head of Draco, the dragon, which is off to the upper left of Hercules. And yet another is Rasalas, the head of the lion, which is high in the southwest.
Rasalhague consists of two stars. One of them is more than twice as big and twice as massive as the Sun, while the other is much smaller than the Sun. The bigger star is actually nearing the end of its life, so it’s starting to undergo changes in its core. Over many millions of years, that’ll cause the star to grow much bigger and brighter.
Rasalgethi is already in that phase of life. It’s hundreds of times wider than the Sun, and thousands of times brighter. And it has not one companion, but two, both of which are also bigger and brighter than the Sun. They, too, eventually will puff up to giant proportions — but not until the current bright star has expired and faded from sight.
Script by Damond Benningfield