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Proxima b could be life-friendly, says co-discoverer

Artist's impression of Proxima b orbiting Proxima Centauri

An artist’s impression of Proxima b orbiting Proxima Centauri. Image Credit: ESO/M. Kornmesser

In late August, the European Southern Observatory (ESO) broke the news announcing the discovery of Proxima b, the closest exoplanet to Earth, fueling hopes of finding an Earth-like planet that could support life. Now, Mikko Tuomi of the University of Hertfordshire, United Kingdom, and co-discoverer of Proxima b, suggests the newly found alien world could be one of the best currently-known extra-solar places to search for microbial organisms.

Proxima b, located some four light-years away, has a mass similar to Earth’s – about 30 percent greater – and is orbiting its parent red dwarf star, Proxima Centauri, every 11.2 days. While the planet’s radius and density is still undetermined precisely, astronomers revealed it lies within the “habitable zone” of its host star and has an equilibrium temperature in the range where water could be liquid on its surface.

Artist’s impression of Proxima b.

Artist’s impression of Proxima b. Image Credit: ESO/M. Kornmesser

“Everything we know about Proxima b suggests that, although it is different, it shares similar features with the earth such that it could be a life-friendly planet,” Tuomi told

The exoplanet’s similar mass to Earth means there is hardly any doubt about the fact the planet has a rocky surface, with comparable composition. According to Tuomi, that in turn implies the planet’s radius is likely only slightly larger than Earth’s radius. However, this is rather theoretical guesswork as currently researchers have no observational information about the exo-world’s radius and therefore cannot estimate its density.

While many physical parameters of Proxima b are still uncertain, it is known the radiation flux on the planet’s surface is some 70 percent of the flux on Earth, making the exoplanet’s surface temperature somewhat lower than on our planet. Moreover, its slightly larger mass suggests a denser atmosphere is possible enabling a stronger greenhouse effect than on Earth.

But could Proxima b really host alien lifeforms? It is important to note when geochemical processes turn into biochemical ones and become identifiable as life, only three basic ingredients are needed.

“First, we need rock, and Proxima b indeed is a planet that certainly has a rocky surface,” Tuomi said, “Second, the most common molecule in the Universe, water, has to be present. We have no evidence of this, but water can be found everywhere in space and there are no reasons why it would not exist on the surface of Proxima b – and the temperatures on its surface likely allow the water to be liquid and for oceans as well. Third, there needs to be carbon dioxide, but that is simply a common primitive atmospheric molecule on all the Earth-sized planets in the solar system.”

Thus, Tuomi concluded this means all the ingredients for life are the most likely there.

“If that is the case, I believe the formation [of] biochemical processes we can call life is rather an inevitability than a once-in-a-blue-moon rare event,” Tuomi said.

However, much work still needs to be done to confirm Proxima b’s conditions to support life. The proximity of the newly detected planet means it can be studied with future space telescopes such as the James Webb Space Telescope. Scientists hope to obtain more information regarding the planet’s properties, and also about the existence of additional planets in the system, by conducting further observations over the coming years. The exoplanet could be even within reach of robotic interstellar missions within a human lifetime.

“This is not the case for the majority of known ‘Earth-like’ exoplanets found by the Kepler spacecraft because they are hundreds of light years away,” Tuomi said.


Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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