Proxima b is the only planet orbiting Proxima Centauri, the third star in the Alpha Centauri system. It is a terrestrial planet (i.e., with a solid surface), 10% larger than the Earth. It was discovered in 2016 and found to harbor life after the first probes arrived in its atmosphere in 2044. Later exploration missions discovered that its crust is relatively rich in osmium, a rare metal on Earth which is suitable for use as the primary construction material in a Void Gate.
Proxima b is strikingly different from Earth. To start with, it is tidally locked to Proxima Centauri due to being much closer to it than Mercury is from the Sun. This means one side of the planet faces Proxima Centauri, leaving it in permanent daylight, while the other side faces away from the star in perpetual darkness.
Proxima b has virtually no water, with sulphuric acid oceans covering half of its surface. Its atmosphere is composed mainly of methane and sulfur dioxide, therefore not breathable and creating a greenhouse effect that maintains an average surface temperature of 80C, with extremes of -10C on its North Pole and 400C on its South Pole.
Proxima b is booming with life, having close to twice as much biomass as Earth. About half of Proxima b’s biomass is estimated to exist under its sulfuric acid oceans, and the other half is land-based. There is no evidence of intelligent life on Proxima b, indicating that evolution is further behind than on Earth. Reasons for this are currently unknown.
Proxima b’s species evolved using strategies analogous to life on Earth, such as how they obtain and consume food, how they move in liquid and solid environments, or how they reproduce passing genetic information from generation to generation. However, that’s where the similarities end.
Life forms have vastly different biochemistry, using sulfuric acid as a solvent and composed of carbon-based proteins incompatible with Earth life. Advanced life forms breathe sulfur dioxide and their metabolic reactions to generate energy are not yet understood.
Take a look at the Proxima b Life Catalog, maintained by SEV, which contains details of species already studied and will continue to be updated as new ones are discovered.