Astronomers Have Discovered an Earth-Sized Exoplanet in Our Cosmic Backyard

But what would potential life look like on this planetary neighbor?

new exoplanet
An artist's impression of Proxima b ESO/M. Kornmesser

Earlier today, astronomers at the European Southern Observatory (ESO) announced that they have officially confirmed the discovery of an exoplanet circling the closest star to our solar system. Though many media reports have trumpeted the potential for the planet to harbor life, the most fascinating features of this new planet are not its similarities to Earth, but its differences, Nadia Drake reports for National Geographic. 

The exoplanet was found orbiting a star called Proxima Centauri. As its name suggests, the red dwarf is the closest star to our own solar system—a mere 4.33 light-years away, Phil Plait reports for Slate. Because it’s so close, scientists have long hoped that a planet might orbit the glowing body, which would allow us to learn more about these alien solar systems and perhaps even visit one.

So for years, astronomers at the ESO studied Proxima Centauri looking for small shifts in its starlight from a planet passing in front. But while early measurements found signs that an object was orbiting every 11 days or so, they still couldn’t rule out something like solar flares were giving off a false signal, Alexandra Witze reports for Nature. In January, Anglada-Escudé and his colleagues added a second telescope to the mix and within a week they were certain they had found an exoplanet.

The planet, dubbed Proxima b, is a hair larger than Earth, with a mass about 1.3 times as big as our home planet’s. Though its star is much dimmer than our own, Proxima b is located much closer to it, putting it squarely in the so-called “Goldilocks zone” that scientists believe gives a planet just the right conditions to contain liquid water, Jennifer Ouellette reports for Gizmodo.

But don't get too excited about little girls and bears roaming its surface. As a red dwarf, it's a particularly volatile type of star and regularly blasts waves of ultraviolet radiation into space, Drake reports. Any life form that may have evolved on the planet would have to have some serious shielding to protect itself from regular showers of radiation. 

Life isn't entirely impossible, however. A new study submitted to the Astrophysical Journal suggests that a particular adaptation could safeguard the planet's potential inhabitants against frequent solar flares. If the hypothetical denizens of the planet could absorb harmful radiation and transform it into fluorescence like certain corals on Earth, then they would stand a fighting chance, Maddie Stone reports for Gizmodo. In the future, scientists could potentially identify life on this and other exoplanets by spotting these fluorescent biosignatures. 

“The idea of biofluorescence as a sign of life is a neat idea,” Adler Planetarium’s Lucianne Walkowicz tells Drake—but it's a hypothetical one. As Drake explains: 

[M]any, many things would have to go right for a biofluorescent signature to be detectable. Fluorescing proteins would need to be much more efficient than they are on Earth, [Walkowicz] says, and such organisms would have to be essentially everywhere. Not to mention that an atmosphere and surface water are not givens in the harsh environments around red dwarfs.

Still, the exoplanet’s proximity to Earth makes it a perfect candidate for future exploration, particularly for programs like the Breakthrough Starshot Initiative, which is developing a tiny spacecraft that sails through the stars on sails powered by lasers. Unlike a larger, traditional spacecraft, these theoretical “nanocrafts” could travel much faster and reach Proxima b in a fraction of the time, allowing scientists to quickly start studying the exoplanet up close, Ouellette reports. Meanwhile, it gives astronomers and engineers a brand-new target to aim for as they develop new, more powerful telescopes to scan the night skies.

“It gives us the target and focus to build the next generation of telescopes and one day maybe even get to visit,” Kipping tells Witze. “It's exactly what we need to take exoplanetary science to the next level.”

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