Planetarium

"How far away could we travel from the Sun and still be able to see it?"


- Question from 8th grader


Hello! I wanted to provide a little background before I post the answer. Actually, this answer is more of an approximation. The Sun is by far the sky's brightest night sky object because we are so close to it: between 91.5 - 94.5 million miles, depending on the time of year. All the other stars are much fainter because they are so far away. (Think about it this way: a light beam requires about 8.3 minutes to travel from the Sun to Earth. A light beam from Proxima Centauri, the closest star to the Sun, requires about 4.2 years to reach Earth. Proxima Centauri is about 262,000 times farther away from us than the Sun.)    

If we were to travel away from the Sun, it would become fainter. At Pluto's distance, the Sun will still be many millions of times brighter than the night sky's brightest star, Sirius. At the distance of Proxima Centauri, the Sun would be about as bright as Procyon, the  brightest star in Canis Minor and the 8th brightest star in our sky. The faintest stars that most people can see are about 185 times dimmer than Procyon. For the Sun to appear this faint to us, we would have to be about 58 light years away from it. Some people have keener eyesight than most of us and they can see fainter stars. However, if we were all in a space vessel that was 58 light years from the solar system, we could still just barely see the Sun. We'd likely need a highly detailed star chart to locate it.

[If you want to see the mathematics on which this response was based, go to our page: The Math Zone! Go to MZ 3: Using the Distance Modulus to determine the Sun's brightness at various distances.]