Proxima B

Proxima B is a planet orbiting Proxima Centauri, it is 1.3% the size of Earth, though slightly less dense. It originally had an atmosphere of 74% Nitrogen, 24% Carbon Dioxide, 1% Argon, 0.7% Oxygen and 0.3% others, yet this started to change in 2110 when the terraforming of the planet begun. The system is 4.243 light years away.