The closest star? The Sun . After the Sun is Proxima Centauri , part of the three-star Alpha Centauri (α Cen) star system. Proxima Centauri is about 25,219,301,250,000 miles or 40,586,533,727,000 kilometers away. So let’s look at this in other ways. A 50-mile high stack of toilet paper stretched out on 1 sheet = 1 million miles scale. Alpha Centauri is often listed as the second closest star to Earth, this is incorrect . Proxima Centauri is the second-closest star and orbits Alpha Centauri.