The Summer Triangle is one of the most prominent star patterns in the sky. But its name isn't quite right. A more accurate name might be the "Most-of-the-Year Triangle." It climbs into the evening sky in May, and doesn't disappear until January.
In fact, it's in good view tonight. It stands high overhead at nightfall, and spends hours descending the western sky.
Its brightest star is Vega, in Lyra, the harp. It's one of the brightest stars in the night sky, so it's easy to find, even from the city.
To the eye alone, the rest of Lyra isn't all that impressive. But binoculars or a telescope reveal an impressive sight: one of its stars is actually a beautiful double star -- one red, the other blue.
The colors mean that the stars have different surface temperatures. A red star is cooler than the Sun, while a blue star is much hotter than the Sun. So just by looking at Delta Lyrae through binoculars, you can see that one star is hotter than the other.
On the sky, Delta Lyrae stands a short distance from Vega. But in space, it's a thousand light-years beyond Vega. The two stars of Delta Lyrae lie at different distances from Earth, though, so they're not related to each other -- they just line up so close in the sky that their light blurs into a single point.
Each star is really much brighter than Vega. So if either star were as close to us as Vega is, Delta Lyrae -- and not Vega -- would be the dazzling leader of the Most-of-the-Year Triangle.
Script by Damond Benningfield and Ken Croswell
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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