Just four light-years from Earth lies the closest known exoplanet, Proxima Centauri b. It has captured imaginations because it could be one of the first exoplanets where extraterrestrial life might exist. But what would it actually be like to land on this distant world?
A Neighbor in Space
Proxima Centauri b orbits Proxima Centauri, a red dwarf star that is part of the Alpha Centauri system. Alpha Centauri consists of three stars: Alpha Centauri A and B, which orbit close together, and Proxima Centauri, which orbits farther away but remains gravitationally linked to its companions. While Proxima Centauri b is the closest known exoplanet, the journey from Earth would still take an unimaginable 165,000 years at current spacecraft speeds.
A Habitable Zone World?
Proxima Centauri b is located in the habitable zone of its star, the region where temperatures could, in theory, allow liquid water to exist. However, being in the habitable zone does not automatically mean the planet is hospitable. Proxima Centauri is a red dwarf, much smaller and cooler than the Sun. It burns hydrogen far more efficiently, giving it a lifespan measured in trillions of years, far beyond the Sun’s eventual demise.
Despite its longevity, the star’s faint output means Proxima Centauri b must orbit extremely close to receive enough energy to potentially support life. This proximity brings serious challenges, including intense stellar activity.
Deadly Solar Flares
Red dwarf stars like Proxima Centauri emit frequent and unpredictable solar flares. These powerful bursts of ultraviolet and X-ray radiation can strip away a planet’s atmosphere over time. Without a protective atmosphere, surface conditions would be harsh, and exposure to radiation could make life impossible on large portions of the planet.
Tidal Locking and Extreme Conditions
Proxima Centauri b is likely tidally locked, meaning one side always faces its star while the other remains in perpetual darkness. The dayside could be extremely hot and irradiated, while the nightside could be frigid and dark. However, there is a potential refuge in the so-called terminator zone, the narrow strip between the day and night sides. In this region, temperatures could be more moderate, making it the most promising area for habitability.
The Atmosphere Question
One of the biggest uncertainties about Proxima Centauri b is whether it has a significant atmosphere. A thin atmosphere could allow surface temperatures to range from -40 degrees Celsius to 30 degrees Celsius, potentially supporting liquid water. Where there is water, life could theoretically exist.
If the atmosphere is absent or extremely thin, the planet’s surface could be inhospitable, dominated by radiation and severe temperature extremes.
A Challenging Home
Even if Proxima Centauri b offers liquid water and moderate temperatures in the terminator zone, survival would require protection from radiation and careful planning to adapt to constant sunlight on one side and eternal darkness on the other. The reality of living on this planet would be dramatically different from anything on Earth, with extreme conditions making every day a challenge.
