What evidence supports that proxima centauri is the closest star to the earth other than the sun?

Answer 1

For stars closer than about 400 light years (LY), we can directly calculate the distance using trigonometry and the parallax shift of the "nearby" stars as compared to the more distant stars far away. By observing the nearby star at times 6 months apart, we have a "baseline" of 2 AU distance, and we can calculate the distance. The closer, the more accurate, of course. Since Proxima Centauri is only 4.2 LY away, our calculation is pretty much spot-on.

Beyond about 400 LY, our distance estimates are based on the difference between the relative magnitude of the star (how bright it looks to us) as compared to the "absolute magnitude", the brightness that we calculate based on the star's spectrum, size and color. So for the red supergiant star Betelgeuse, our estimated distance of 650 LY could be off 140 LY either way!

Answer 2

Proxima Centauri is the closest known star to Earth (other than the Sun) based on current astronomical measurements. Its proximity has been determined through various methods, including stellar parallax and astrometric observations. This, along with its relatively low luminosity and location in the Alpha Centauri star system, makes it the closest known star to our solar system.