Scientists have discovered an exoplanet that may be habitable. (Photo: NASA Ames/JPL-Caltech/Public domain)

Astronomers from the European Southern Observatory (ESO) have made a stunning discovery 20 years in the making: an exoplanet that circles around the Sun’s nearest star, Proxima Centauri. Scientists have been looking for this world since the first exoplanet—a planet that orbits a star outside our solar system—was discovered in 1995.

The newly discovered exoplanet is thought to be the closest place for life to exist outside our solar system. The planet is close enough for scientists to study and to determine whether human life could flourish there. 

The planet, named Proxima b, orbits its parent star every 11 days and has an estimated surface temperature that would allow for the presence of liquid water. Astronomers say the surface is rocky and 1.3 times bigger than our Earth.  

Astronomer Guillem Anglada-Escudé, from Queen Mary University of London, led the mission, called the Pale Red Dot campaign, to find the exoplanet. They looked for the tiny back-and-forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet. 

“Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us,” said Anglada-Escudé in an ESO release. “Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next.”

Proxima b is in a “habitable zone” because of its distance from the star it orbits. For astronomers the world-over the news is a game changer.

“It’s the holy grail,” Mercedes López-Morales, an astronomer from the Harvard-Smithsonian Center for Astrophysics, tells Atlas Obscura.

The next step for López-Morales and her team at Harvard is to detect whether the new planet has an atmosphere and an ozone layer. The presence of an ozone layer means oxygen, which means air. It will certainly keep the team busy over the next couple of years.

Astronomers will be cautiously optimistic, says David Kipping, an astronomer at Columbia University. His team is also involved in research related to the new discovery, and will be working on it closely in the future. Kipping is in no doubt about the potential impact of this news. “If independently confirmed, this would be a historic discovery shaping the entire future of our field,” he tells Atlas Obscura.

And while this was a monumental discovery, the early predictions suggest the atmosphere may be damaged because the star is highly active and has powerful winds. This means, as the first indications show, the atmosphere may be eroded, says López-Morales, and not like Earth’s.

Nonetheless, no one will know until the tests are done with a powerful telescope. The astronomers will now undertake research that asks a legitimate question: does life already exist on this new planet, and will it be conducive for human life in the future?

To reach this point is a major step forward, and the team involved in the discovery deserve huge plaudits, says López-Morales.

“These guys can go on vacation for a year now.”