Earth-like planet found orbiting closest star to sun

By Barry Eitel

SAN FRANCISCO

An international team of astronomers announced Wednesday they have discovered a rocky, Earth-like planet that might harbor life orbiting Proxima Centauri, the closest star to the sun.

The planet, designated Proxima b, is 4.22 light-years from Earth – essentially a celestial next-door-neighbor. At 40 trillion kilometers (25 trillion miles) away, it is easily the closest Earth clone ever found. If a small, unmanned spacecraft were launched in the next few years, it could reach Proxima b by 2100; children living in 2016 would be alive to see the craft’s arrival.

Proxima Centauri is classified as a red dwarf star, meaning it is much smaller and colder than the sun. Even though Proxima b has an orbit closer to its home star than Mercury, Proxima Centauri’s cooler temperature leads scientists to believe liquid water could form on Proxima b’s surface.

A study of the discovery will be published Thursday in the journal Nature. Astronomers from the United States, Europe and South America worked on the project.

"The discovery of the potentially habitable planet around Proxima Cen is the culmination of 30 years of work,” study author Paul Butler of the Carnegie Institution for Science said in a statement. “This work has resulted in the discovery of hundreds of planets around the nearest stars, and now a potentially habitable planet around the nearest star in the sky.”

By closely observing Proxima Centauri and other stars, researchers believe potentially habitable planets are actually fairly common in the universe.

“This work … points the way to the future when such planets will be directly observed with giant ground- and space-based telescopes,” Butler added.

The experience of living on Proxima b would be quite alien compared to Earth. The planet does not rotate, for example, so it does not experience days. It is also bombarded by ultraviolet radiation due to its proximity to Proxima Centauri, but life could still survive.