The Atlanta Journal-Constitution
Scientists find planet that’s like Earth
Tiny probe could be sent to explore by the year 2060.
Astronomers say they’ve found a planet where life could be possible — and it’s orbiting a star near Earth’s solar system.
WASHINGTON — After scanning the vast reaches of the cosmos for Earth-like planets where life might exist, astronomers have found one right next door.
They reported Wednesday they had discovered a planet that’s rocky like Earth and only slightly bigger orbiting Proxima Centauri, the nearest star to our solar system. It is probably in the not-too-hot, not-too-cold region — which they call the “Goldilocks Zone” — where liquid water, a key to life, is possible if the planet has an atmosphere.
And it is a mere 4.22 lightyears from Earth, or about 25 trillion miles.
It is easily the closest potentially habitable planet ever detected outside our solar system — and one that could be reachable by tiny, unmanned space probes before the end of the century, within the lifespan of some people alive today.
The international team of astronomers that announced the discovery did not actually see the planet but deduced its existence by using telescopes to spot and precisely calculate the gravitational pull on the star by a possible orbiting body — a tried-and-true method of planet-hunting.
“We hit the jackpot here,” said Guillem Anglada-Escude, an astrophysicist at the Queen Mary University of London and lead author of a study on the discovery in the journal Nature. He said the planet is “more or less what we have on Earth.”
They’re calling it Proxima b, and while it could be Earthlike, it would probably look very alien. It is 4.6 million miles from its red dwarf star, or just one-twentieth of the distance between Earth and the sun, creating an incredible orange sky with no blue — sort of like a perpetual sunset. And if that’s not different enough, the planet circles its star so quickly that its year is about 11 Earth days long.
The planet doesn’t rotate, so one side is always facing its star and the other side is always dark and colder. It is bombarded with X-rays and ultraviolet light, but that wouldn’t necessarily preclude life, particularly forms that exist underground, scientists said.
Scientists in the past 20 years have found more than 3,000 planets outside our solar system, or “exoplanets.” And more than 40 of them seem to be in the habitable zone. But this one “basically puts a giant flashing neon sign on the nearest star saying: ‘See this right here,’” said study co-author R. Paul Butler of the Carnegie Institution for Science.
It would take more than eight years for an energy pulse or radio signal traveling at the speed of light to go there and back. NASA’s New Horizons probe, the fastest spacecraft launched, left Earth hurtling toward Pluto at about 36,000 mph. At that speed, it would take more than 78,000 years to get there.
But earlier this year, an allstar team of scientists and business leaders including Stephen Hawking announced Breakthrough Starshot, a project to send out hundreds of light-powered space probes that would weigh about a gram, travel at one-fifth the speed of light and send pictures back to Earth.
Breakthrough Starshot executive director Pete Worden, a former top NASA official, said organizers are hoping to include Proxima in their plans. Even at the hoped-for speed, it would take 20 years to get there and four more years for photos to come back. Worden said he hopes to launch a probe by 2060.
Yet in the vastness of space, Proxima b is practically just over the fence, “like your next-door neighbor,” Butler said. Proxima b is more than 50 trillion miles closer than the previous closest potentially habitable exoplanet.
The next step may be for a powerful Earth or space telescope to get an actual image of the planet, Butler said. But even when that comes, it will only be a single dot.