Based on how bright the stars look to our eyes alone, Deneb ranks among the 20 brightest stars in the night sky. Because the stars are at different distances, though, that ranking is a little misleading. If we could arrange them based on their true brightness, Deneb would outshine them all. In fact, it might be the brightest of all the stars that are easily visible to the unaided eye.

Deneb is high in the east-northeast at nightfall, at the lower left corner of the bright Summer Triangle.

Deneb is a blue supergiant – it’s much bigger, heavier, and hotter than the Sun. And it’s much, much brighter. Exactly how much brighter isn’t certain. That’s because there’s disagreement about the star’s distance.

Astronomers have measured the distance with several techniques. Some are more direct, while others are based on models of different types of stars. That’s yielded estimates of about 1400 to 2600 light-years.

And that makes a big difference. At the greater distance, Deneb would be almost four times brighter than at the smaller one. So Deneb’s true luminosity – the value when you add up all wavelengths of light – is somewhere between 50,000 and 200,000 times the Sun’s. If the high end of that range is correct, then Deneb is one of the brighter stars in the entire galaxy – and perhaps the brightest star that’s easily seen with the eye alone.

Script by Damond Benningfield