Final answer:
The constellation closest to us is Centaurus, specifically Alpha Centauri. This binary star system is located 4.4 light-years away from us. Another star in the same constellation, Proxima Centauri, is slightly closer at a distance of 4.3 light-years.
Step-by-step explanation:
The constellation closest to us is Centaurus, and we know this because the three nearest stars to the Sun are located in this constellation. The brightest of these three stars is Alpha Centauri, which is a binary star system consisting of two stars in mutual revolution.
These two stars are 4.4 light-years away from us. Proxima Centauri, a faint star in the same constellation, is slightly closer to us at a distance of 4.3 light-years.