Valdosta Daily Times

Top News

November 5, 2013

Study: 8.8 billion Earth-size, just-right planets

WASHINGTON — Space is vast, but it may not be so lonely after all: A study finds the Milky Way is teeming with billions of planets that are about the size of Earth, orbit stars just like our sun, and exist in the Goldilocks zone — not too hot and not too cold for life.

Astronomers using NASA data have calculated for the first time that in our galaxy alone, there are at least 8.8 billion stars with Earth-size planets in the habitable temperature zone.

The study was published Monday in the journal Proceedings of the National Academy of Science.

For perspective, that’s more Earth-like planets than there are people on Earth.

As for what it says about the odds that there is life somewhere out there, it means “just in our Milky Way galaxy alone, that’s 8.8 billion throws of the biological dice,” said study co-author Geoff Marcy, a longtime planet hunter from the University of California at Berkeley.

The next step, scientists say, is to look for atmospheres on these planets with powerful space telescopes that have yet to be launched. That would yield further clues to whether any of these planets do, in fact, harbor life.

The findings also raise a blaring question, Marcy said: If we aren’t alone, why is “there a deafening silence in our Milky Way galaxy from advanced civilizations?”

In the Milky Way, about 1 in 5 stars that are like our sun in size, color and age have planets that are roughly Earth’s size and are in the habitable zone where life-crucial water can be liquid, according to intricate calculations based on four years of observations from NASA’s now-crippled Kepler telescope.

If people on Earth could only travel in deep space, “you’d probably see a lot of traffic jams,” Bill Borucki, NASA’s chief Kepler scientist, joked Monday.

The Kepler telescope peered at 42,000 stars, examining just a tiny slice of our galaxy to see how many planets like Earth are out there. Scientists then extrapolated that figure to the rest of the galaxy, which has hundreds of billions of stars.

For the first time, scientists calculated — not estimated — what percent of stars that are just like our sun have planets similar to Earth: 22 percent, with a margin of error of plus or minus 8 percentage points.

Kepler scientist Natalie Batalha said there is still more data to pore over before this can be considered a final figure.

There are about 200 billion stars in our galaxy, with 40 billion of them like our sun, Marcy said. One of his co-authors put the number of sun-like stars closer to 50 billion, meaning there would be at least 11 billion planets like ours.

Based on the 1-in-5 estimate, the closest Earth-size planet that is in the habitable temperature zone and circles a sun-like star is probably within 70 trillion miles of Earth, Marcy said.

And the 8.8 billion Earth-size planets figure is only a start. That’s because scientists were looking only at sun-like stars, which are not the most common stars.

An earlier study found that 15 percent of the more common red dwarf stars have Earth-size planets that are close-in enough to be in the not-too-hot, not-too-cold Goldilocks Zone.

Put those together and that’s probably 40 billion right-size, right-place planets, Marcy said.

And that’s just our galaxy. There are billions of other galaxies.

Scientists at a Kepler science conference Monday said they have found 833 new candidate planets with the space telescope, bringing the total of planets they’ve spotted to 3,538, but most aren’t candidates for life.

Kepler has identified only 10 planets that are about Earth’s size circling sun-like stars and are in the habitable zone, including one called Kepler 69-c.

Because there are probably hundreds of planets missed for every one found, the study did intricate extrapolations to come up with the 22 percent figure — a calculation that outside scientists say is fair.

“Everything they’ve done looks legitimate,” said MIT astronomer Sara Seager.

1
Text Only
Top News
  • Kingston’s loss means less clout for Ga.

    For two decades, Rep. Jack Kingston was a congressman who routinely crushed his opponents on election night — winning a new term every other year with vote totals between 63 and 77 percent.

    July 28, 2014

  • IMG_3745.jpeg Gas leak on West Adair

    A gas leak has occured on West Adair Street, between Tombs and Oak Street. The leak began just after 11 a.m.

    July 28, 2014 1 Photo

  • salmonella 2 copy.jpg Trial nears for suspects in salmonella case

    Three people accused of scheming to manufacture and ship salmonella-tainted peanuts that killed nine people, sickened more than 700 and prompted one of the largest food recalls in history are set to go to trial this week in south Georgia.

    July 28, 2014 1 Photo

  • AP4507280123 copy.jpg Today in History for Monday, July 28, 2014
    Today is Monday, July 28, the 209th day of 2014. There are 156 days left in the year. 
     

    July 28, 2014 1 Photo

  • Commercial driver training program expanding

    Department of Driver Services (DDS) Commissioner Rob Mikell announced recently an expansion of the commercial driver training program administered by the Agency’s Regulatory Compliance Division. DDS will now offer a Commercial Driver License (CDL) Instructor Training Class for customers who have applied to be CDL instructors. The session will provide additional guidance as the applicants prepare for the final exam.

    July 28, 2014

  • Tentative deal reached on VA reform

    The chairmen of the House and Senate Veterans Affairs committees have reached a tentative agreement on a plan to fix a veterans’ health program scandalized by long patient wait times and falsified records covering up delays.

    July 27, 2014

  • Heat advisory for much of South Georgia

    A heat advisory is in place for much of South Georgia until 7 p.m.

    July 27, 2014

  • 2 injured in western Georgia small plane crash

    Fire officials say two people were hospitalized after small plane crash in western Georgia. 

     

    July 27, 2014

  • Nuclear Construction_Rich(1) copy.jpg Promises of easier nuclear construction fall short

    The U.S. nuclear industry has started building its first new plants in decades using prefabricated Lego-like blocks meant to save time and money and revive the once promising energy source.
    So far, it’s not working.

    July 27, 2014 1 Photo

  • Deadline nears for alligator hunt

    Gator hunting is no longer reserved for University of Georgia sports fans, but hunters must file applications by the end of July.

    July 27, 2014

Top News
Poll

Do you agree with the millage rate increases?

Yes. We need to maintain services
No. Services should have been cut.
     View Results