Epsilon Lyrae
The four stars of the system known as Epsilon Lyrae are like dancers in a never-ending ballet. The stars form two pairs, with the stars of each pair twirling around each other once every millennium or so. And the two pairs twirl around each other, too, in a slow turn that takes hundreds of millennia.
This graceful system is also known as the Double Double.
All four of its stars are a little hotter and more massive than the Sun -- and a lot brighter. And all the stars are siblings, because they were born from a single cloud of gas and dust.
The stars of each "double" are separated from each other by about 150 times the distance from Earth to the Sun. Even so, from a planet orbiting one of the stars, the other star in the pair would still shine many times brighter than a full Moon. So except for every thousand years or so, when the distant star appeared only in the daytime sky, nighttime on such a planet wouldn't get very dark.
The "double double" of Epsilon Lyrae is visible to the unaided eye. It's near the brilliant star Vega, which is high overhead at nightfall. To most of us, much fainter Epsilon Lyrae looks like a single star. But those with especially good eyesight might just be able to split them into two points of light -- the two pairs.
Binoculars provide a clear view of the two pairs. And a telescope splits each pair into two stars, allowing the Double Double to shine through in all its glory -- a beautiful family of stars.
Script by Damond Benningfield, Copyright 2009
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