Study: Billions of Earth-size planets in Milky Way - Hawaii News Now - KGMB and KHNL

Study: Billions of Earth-size planets in Milky Way

By ALICIA CHANG
AP Science Writer

LOS ANGELES (AP) - Our Milky Way is home to at least 17 billion planets that are similar in size to Earth, a new estimate suggests. That's more than two Earth-size planets for every person on the globe.

Just how many are located in the sweet spot where water could exist is "simply too early to call," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, who presented his work at an astronomy meeting Monday.

It's the first reliable tally of the number of worlds outside the solar system that are the size of Earth, but the hunt for our twin is far from over.

Despite the explosion of exoplanet discoveries in recent years, one find remains elusive: A planet that's not only the right size but also in the so-called Goldilocks zone where it's not too hot or too cold for water to be in liquid form on the surface.

The sheer number of Earth-size planets gives astronomers a starting point to narrow down which ones are in the habitable zone.

Fressin and his team came up with their figure by conducting a fresh analysis of data collected by NASA's Kepler spacecraft, which was launched in 2009 to track down other Earths. They estimated at least one in six stars in the galaxy hosts a planet the size of ours, translating to at least 17 billion Earth-size worlds.

Using a different method, a team from the University of California, Berkeley and University of Hawaii separately came up with a similar estimate. They calculated 17% of distant stars have planets that are the same size as Earth or slightly larger.

The findings were presented at the American Astronomical Society in Long Beach, Calif.

Meanwhile, the Kepler spacecraft continues to spot planets as they pass between Earth and the star they orbit. It found 461 new candidate planets, bringing the total to 2,740 potential planets, said mission scientist Christopher Burke at the SETI Institute.

Most of the new Kepler finds were driven by discoveries of Earth-size planets and super-Earths. 4 of those are thought to reside in the Goldilocks zone, but more observations are needed.

Fressin said it's clear that rocky planets abound outside the solar system.

"If you look up on a starry night, each star you're looking at - almost each 1 of them - has a planetary system," Fressin said.

Follow Alicia Chang at http://twitter.com/SciWriAlicia

Online:

Kepler mission: http://www.nasa.gov/kepler

Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Hawaii News Now headlinesNewsMore>>

  • Puerto Rico marks 1 year since Maria with song and sadness

    Puerto Rico marks 1 year since Maria with song and sadness

    Thursday, September 20 2018 12:58 PM EDT2018-09-20 16:58:38 GMT
    Friday, September 21 2018 6:06 AM EDT2018-09-21 10:06:18 GMT
    (AP Photo/Ramon Espinosa). In this Sept. 8, 2018 photo, Alma Morales Rosario poses for a portrait between the beams of her home being rebuilt after it was destroyed by Hurricane Maria one year ago in the San Lorenzo neighborhood of Morovis, Puerto Rico...(AP Photo/Ramon Espinosa). In this Sept. 8, 2018 photo, Alma Morales Rosario poses for a portrait between the beams of her home being rebuilt after it was destroyed by Hurricane Maria one year ago in the San Lorenzo neighborhood of Morovis, Puerto Rico...
    Puerto Ricans are marking the one-year anniversary of Hurricane Maria with choirs, protests and a funeral procession.More >>
    Puerto Ricans are marking the one-year anniversary of Hurricane Maria with choirs, protests and a funeral procession.More >>
  • Man dies in officer-involved shooting at Honolulu highrise

    Man dies in officer-involved shooting at Honolulu highrise

    Friday, September 21 2018 4:09 AM EDT2018-09-21 08:09:13 GMT
    A man was killed Thursday evening in an officer-involved shooting at a Honolulu highrise. (Image: Hawaii News Now)A man was killed Thursday evening in an officer-involved shooting at a Honolulu highrise. (Image: Hawaii News Now)

    Police reportedly fatally shot a suspect after an operation at the Century Center building.

    More >>

    Police reportedly fatally shot a suspect after an operation at the Century Center building.

    More >>
  • Telling men to 'step up,' Sen. Hirono strides into spotlight

    Telling men to 'step up,' Sen. Hirono strides into spotlight

    Thursday, September 20 2018 6:29 PM EDT2018-09-20 22:29:45 GMT
    Friday, September 21 2018 1:52 AM EDT2018-09-21 05:52:43 GMT
    (AP Photo/J. Scott Applewhite). Sen. Mazie Hirono, D-Hawaii, with Sen. Kirsten Gillibrand, D-N.Y., left, is applauded by demonstrators as the arrive to speak to reporters in support of professor Christine Blasey Ford, who is accusing Supreme Court nomi...(AP Photo/J. Scott Applewhite). Sen. Mazie Hirono, D-Hawaii, with Sen. Kirsten Gillibrand, D-N.Y., left, is applauded by demonstrators as the arrive to speak to reporters in support of professor Christine Blasey Ford, who is accusing Supreme Court nomi...
    Hawaii Sen. Mazie Hirono steps into the spotlight as she has unexpectedly become one of the most outspoken senators in Christine Blasey Ford's defense.More >>
    Hawaii Sen. Mazie Hirono steps into the spotlight as she has unexpectedly become one of the most outspoken senators in Christine Blasey Ford's defense.More >>
Powered by Frankly