by Timothy Ferris
Double stars are good viewing in telescopes of all sizes. The larger the aperture of a given telescope, the closer together the double stars it can resolve, or split. This colorful double star, Albireo, 385 light years from Earth, is one of the most beautiful in northern skies. (It is also the official star of the University of California—because its blue and gold hues closely resemble Cal Berkeley's school colors.) Some double stars are line-of-sight coincidences but many, like Alberio, are true siblings that formed together and continue to orbit around their common center of gravity. This photo was taken digitally through an 18-inch telescope, projecting the image through the telescope's eyepiece to increase the apparent separation of the stars.