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Old 12-04-2016, 03:47 PM
wolfpup wolfpup is online now
Join Date: Jan 2014
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Originally Posted by Nars Glinley View Post
Would it appear much different than any other star when viewed from Earth?
In short, yes. I didn't work through any of the detailed calculations, but one can quickly see this just by taking Rigel A as an example and doing some quick guesstimates. Rigel A is described as "a blue-white supergiant that is estimated to be anywhere from 120,000 to 279,000 times as luminous as the Sun"; it's the seventh brightest star in the sky despite being 863 light-years away.

By contrast, Sirius A has 25 times the luminosity of the sun and is only twice as far away as Proxima Centauri, and the combination makes it by far the brightest star in the sky.

Anyway by my rough guesstimates, its absolute magnitude tells us that at about 32 ly, Rigel would be intense and unmistakeable -- 40 times brighter than Venus at its brightest, which itself is 15 times brighter than Sirius. At the distance of Proxima Centauri, it would dominate the night sky and, though still only visible as a point of light, would be bright enough to provide nighttime illumination and cast a shadow, comparable to the moon.