# How large would Alpha Centauri AB be in the sky, when observed from exoplanet Proxima C?

Context: I am creating a hard science-fiction world set in the Alpha Centauri system.

How large and bright would the binary star Alpha Centauri AB in the sky, when observed from an exoplanet (Proxima C) in Proxima Centauri? Would it be visible during the day? Is it close enough to cast any light onto the planet?

• Welcome to worldbuilding. Can you explain what have you already searched on your own? At the moment your question sounds a bit like "do the math for me". Please read the help center for what we want from a good question
– L.Dutch
Oct 13, 2021 at 19:12
• I know that our sun is 8.3 light-minutes from Earth. After conversion, the Alpha Centauri AB binary system that Proxima Centauri orbits is 105,192 light minutes away. So since the Alpha Centauri A and B stars are sun-like, if we assume they are the same size as the sun, then they would be 12673 smaller in the sky. However this does not account for brightness, and I'm not sure how the two stars would combine to create a new star, and how large that star would be. Oct 13, 2021 at 19:19
• While we do allow real-world questions, there is a discussion going on about clarifying their suitability without an actual worldbuilding problem. Do you have an actual worldbuilding problem? If not, this question might be better asked at Astronomy. Oct 13, 2021 at 20:05
• Magnitude and Luminosity calculator Oct 13, 2021 at 21:16