Stargazing: The Double Star Alberio

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The clear nights of early autumn offer stargazers a great opportunity to grab a small telescope or binoculars and take a look at the hidden celestial objects that can be seen only through a "looking glass."

This week, look overhead at the Milky Way and the high-flying double star Alberio in the Summer Triangle constellation of Cygnus. Seen at even slight magnification through binoculars or a small telescope, the third-magnitude Albireo unfolds from a single point of light into a beautiful double star. The contrasting bright "golden yellow" primary star and blue or "sapphire" companion have been called the most beautiful double stars in the sky. At 386 light-years distant, these two bright stars orbit around a common center of gravity under their mutual gravitational attraction.

Look for Cygnus, the celestial Swan, high overhead around 9:30 p.m. Deneb, the brightest star in Cygnus, is directly overhead. It marks the swan's tail. Alberio, 20 degrees to the lower right of Deneb, marks the swan's head.



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