Summer’s most colorful double star is calling your name. Albireo (al-BEER-ee-oh), in the foot of the Northern Cross, is a gorgeous gold and pale blue pair that even the smallest telescope can split. With good focus and steady hands, 10x binoculars will cleave it.
The two stars, which appear to the naked eye as a single star, are about 380 light years away and so far apart from each other, that to be honest, astronomers still aren’t certain they’re physically connected. Assuming they’re gravitationally bound, they orbit one another with a period upward of 75,000 years. Albireo became a triple star in 1976, when astronomers discovered that the brighter orange star had a very close companion beyond the reach of amateur telescopes.
Luckily for skywatchers, Albireo is easy find. Using the little map, look high up in the southeast at nightfall to trace the grand outline of the Summer Triangle defined by the bright stars Vega, Deneb and Altair.
Deneb in the Northern Cross (also known as Cygnus the Swan) sits at the top of the Triangle and marks the “head” of the Northern Cross (known formally as Cygnus the Swan); Albireo lies at the “foot” of the cross. Albireo is well placed June through early autumn as it swings across the southern sky.
I like to use my lowest magnification when I stop by for a look in the telescope. Not only are the colors more apparent but the two stars shine crisply against the diamond dust of fainter Milky Way stars.
The origin of the name Albireo is rooted in the Arabic language but became corrupted through mistranslation and misunderstandings to the point that it no longer means anything in particular. No matter. It still sounds very good to the ear, and looks even better to the eye.
Albireo has lots of company. Somewhere around half of all stars are double or multiple. All manner of pairs exist – everything from almost impossible to split to widely-separated duos you can sever with your naked eye. They’re everywhere. I’ll often stumble across a potential double, note its position and backcheck to see if it’s a real, physical pair or one of many line-of-sight or “optical” doubles that masquerade as the real thing.
Dust off that telescope and make Albireo your next stop on a summer night.