Sci­en­tists spot what could be an­other Earth

Rocky neigh­bor just 25 tril­lion miles away

Baltimore Sun - - NATION & WORLD - By Seth Boren­stein

WASH­ING­TON — Af­ter scan­ning the vast reaches of the cos­mos for Earth-like plan­ets where life might ex­ist, as­tronomers have found one right next door.

A planet that’s rocky like Earth and only slightly big­ger has been dis­cov­ered or­bit­ing Prox­ima Cen­tauri, the near­est star to our so­lar sys­tem, sci­en­tists re­ported Wed­nes­day.

It is prob­a­bly in the not-too-hot, not-too-cold “Goldilocks Zone” where wa­ter — a key to life — is pos­si­ble, if the planet has an at­mos­phere.

And it is 4.22 light-years from Earth, or nearly 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, in time for some peo­ple alive to­day to wit­ness it.

The in­ter­na­tional team of as­tronomers that an­nounced the dis­cov­ery did not ac­tu­ally see the planet but de­duced its ex­is­tence in­di­rectly, by us­ing tele­scopes to spot and pre­cisely cal­cu­late the grav­i­ta­tional pull on the star by a pos­si­ble or­bit­ing body — a triedand-true method of plan­ethunt­ing.

“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 like Earth in the im­por­tant fea­tures, it would prob­a­bly still look alien.

It is 4.6 mil­lion miles from its red dwarf star, or just 1/20th of the dis­tance be­tween Earth and the sun, cre­at­ing an in­cred­i­ble or­ange sky with no blue, so it looks like a per­pet­ual sun­set.

And if that’s not dif­fer­ent enough, the planet cir­cles its star so quickly that its year is about 11 days.

The planet doesn’t ro­tate, so one side is al­ways fac­ing its star and the other A ren­der­ing of the planet or­bit­ing Prox­ima Cen­tauri, the near­est star to our so­lar sys­tem. side is al­ways dark and colder. It is bom­barded with X-rays and ul­travi­o­let light, but that wouldn’t nec­es­sar­ily be fa­tal to life, since life can 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.

Ear­lier this year, an all­star team of sci­en­tists and busi­ness l ead­ers 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 photos 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 will take 20 years to get there and four more years for photos to come back.

Wor­den said he hopes they will launch by 2060.

Yet in the vast­ness of space, Prox­ima b is prac­ti­cally just over the fence, “like your next-door neigh-

M. KORN­MESSER/EURO­PEAN SOUTH­ERN OB­SER­VA­TORY

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