News / Science & Technology

Study Finds Billions of Earth-like Planets

Illustration of planets that are habitable based on their proximity to the sun. (Photo credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley)
Illustration of planets that are habitable based on their proximity to the sun. (Photo credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley)
Rick Pantaleo
Astronomers from the University of California, Berkeley, and the University of Hawaii, Manoa say that based on new analysis of Kepler spacecraft data, one in five stars similar to our own sun are orbited by planets about the size of Earth, with a surface temperature that would be favorable to support life.

 

"What this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye," said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler data. "That is amazing,"

 

Petigura, along with his colleagues Geoffrey Marcy from UC Berkeley and Andrew Howard from the University of Hawaii, have had their analysis published online in the journal Proceedings of the National Academy of Sciences.
 

The researchers point out that just because an exoplanet is Earth-sized or is in an Earth-sized orbit does not automatically mean that it can to support life, even if their orbits are within a star’s habitable zone, where temperatures are not too hot or too cold.


"Some may have thick atmospheres, making it so hot at the surface that DNA-like molecules would not survive," Marcy said. "Others may have rocky surfaces that could harbor liquid water suitable for living organisms. We don't know what range of planet types and their environments are suitable for life."

Artist's impression of the planet Kepler-78b and its host star. (Karen Teramura/UHIfA)Artist's impression of the planet Kepler-78b and its host star. (Karen Teramura/UHIfA)
x
Artist's impression of the planet Kepler-78b and its host star. (Karen Teramura/UHIfA)
Artist's impression of the planet Kepler-78b and its host star. (Karen Teramura/UHIfA)
Last week Marcy, Howard and their colleagues made news when they announced that they found Kepler-78b, an Earth-sized exoplanet with the same density and a core made up of the same mixture of rock and iron as our own planet.

But since it orbits so close to its star, this newly-discovered rocky planet has a blazing surface temperature of about 2,200 degrees Kelvin, which is far too hot to support life as we know it.

The team focused on 42,000 stars that are like the sun or slightly cooler and smaller. Among those stars, the researchers said they found 603 candidate planets orbiting them. Of these candidate exoplanets, only 10 were Earth-sized, meaning that they were about one to two times the diameter of Earth and orbiting their star at a distance that would provide life supporting temperatures.

To find how many other Earth-sized planets residing in habitable zones they missed in their search, the researchers put planet-finding algorithms devised by Petigura through a number of tests. In these tests, Petigura actually threw in some fake planets into the actual Kepler data to find out which planets his software could detect and which it couldn't.

"What we're doing is taking a census of extrasolar planets, but we can't knock on every door. Only after injecting these fake planets and measuring how many we actually found, could we really pin down the number of real planets that we missed," Petigura said.

NASA's Kepler spacecraft observed 150,000 stars within a field in the constellation Cygnus. (NASA)NASA's Kepler spacecraft observed 150,000 stars within a field in the constellation Cygnus. (NASA)
x
NASA's Kepler spacecraft observed 150,000 stars within a field in the constellation Cygnus. (NASA)
NASA's Kepler spacecraft observed 150,000 stars within a field in the constellation Cygnus. (NASA)
Taking several factors into consideration, such these missing planets, and that only a small number of Earth-like exoplanets are situated in such way that they can be seen transiting in front of their host stars from Earth, the team estimated that 22 percent of all sun-like stars in the galaxy have Earth-size planets in their habitable zones.

"Until now, no one knew exactly how common potentially habitable planets were around Sun-like stars in the galaxy," said Marcy.

Although they found all of the possibly habitable planets circling around cooler K stars, or Orange Dwarfs, which are somewhat smaller than our sun, the researchers said that the results of their analysis could also be inferred to G stars like the sun.

The researchers speculated that if the Kepler spacecraft hadn’t been crippled by technical malfunctions this past spring and was able to fully continue its research mission, it would have been able to gather enough data to directly detect some Earth-size planets in the habitable zones of G-type stars.

This new, more thorough analysis of Kepler data made by the researchers shows that "nature makes about as many planets in hospitable orbits as in close-in orbits," said Howard.

You May Like

Video Indiana Controversy Points to Divergent Notions of Religious Freedom

Gay-marriage opponents are looking for ways to maintain their beliefs in face of changing culture, one writer says More

UNICEF Denies North Korean Measles Outbreak

Agency dismisses Russian media report after government, WHO assurances More

Turkey Seen Taking Harder Stance Against Militant Kurds

Stance comes as President Recep Tayyip Erdogan is being seen as moving closer to generals More

This forum has been closed.
Comment Sorting
Comments
     
by: Steve Hopkins from: New York
November 06, 2013 2:23 PM
That means there's probably somebody, somewhere on one or more of these billions of planets watching Brady Bunch reruns on a protoplasmic TV, thanking their lucky stars that they don't live here. Still, it's beyond obvious that the cosmos is teeming with life, intelligent and otherwise, some of it benevolent and syrupy-sweet and some of it bent on conquest and destruction, like us. Sometimes you just have to open your mind to see the possibilities. Here's a song to help you do that ...

by: Jim from: Philly
November 05, 2013 7:22 PM
Amazing stuff. Every year they have more information thats exciting . Can't wait til they actually discover life on another planet intelligent or not though intelligent would be awesome. Unless they are already here and NASA is just trying to get us more comfortable with the idea before the big announcement that we are not alone. ;)

by: Rb from: WW
November 05, 2013 4:57 PM
Amos 8: Seek him that makes the seven stars and Orion, and turns the shadow of death into the morning, and makes the day dark with night: that calls for the waters of the sea, and pours them out on the face of the earth: The LORD is his name
In Response

by: fimani from: botswana
November 10, 2013 11:42 AM
try harder guys may be u shall find us planet haven,and stop living in confusion

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Indiana Controversy Highlights Divergent Meanings of Religious Freedomi
X
Jerome Socolovsky
April 01, 2015 1:41 AM
Indiana’s state government has triggered a nationwide controversy by approving a law that critics say is aimed at allowing discrimination against gays and lesbians. The controversy stems from divergent notions of religious freedom in America. VOA's Jerome Socolovsky reports.
Video

Video Indiana Controversy Highlights Divergent Meanings of Religious Freedom

Indiana’s state government has triggered a nationwide controversy by approving a law that critics say is aimed at allowing discrimination against gays and lesbians. The controversy stems from divergent notions of religious freedom in America. VOA's Jerome Socolovsky reports.
Video

Video Nigerians Welcome Buhari's Return to Power

Crowds of jubilant Nigerians nationwide have celebrated the return to power of former military ruler Muhammadu Buhari. The retired army general won this year's presidential election with more than 2 million votes more than incumbent President Goodluck Jonathan. Buhari's supporters hope he can strengthen the country's economy and security once he takes office in late May. Zlatica Hoke has this story.
Video

Video Report: State of Black America a 'Tale of Two Nations'

The National Urban League has described this year's "State of Black America" report as a "tale of two nations." The group's annual report, released earlier this month (March), found that under an equality index African Americans had only 72% parity compared to whites in areas such as education, economics, health, social justice and civic engagement. It’s a gap that educators and students at Brooklyn’s Medgar Evers College are looking to close. VOA's Daniela Schrier reports from the school.
Video

Video Film Tells Story of Musicians in Mali Threatened by Jihadists

At this year's annual South by Southwest film and music festival in Austin, Texas, some musicians from Mali were on hand to promote a film about how their lives were upturned by jihadists who destroyed ancient treasures in the city of Timbuktu and prohibited anyone from playing music under threat of death. As VOA’s Greg Flakus reports from Austin, some are afraid to return to their hometowns even though the jihadists are no longer in control there.
Video

Video Gamma Ray Observatory to Open Soon in Mexico

American and Mexican scientists have completed construction of the world's largest gamma ray observatory, situated high in central Mexico’s Sierra Negra Mountain. The observatory's huge array of water-based detectors will soon start discovering secrets about black holes and supernovas. VOA’s George Putic reports.
Video

Video Ebola Vaccine Trials Underway in West Africa

Ebola has claimed the lives of more than 10,000 people in West Africa. Since last summer, researchers have rushed to get anti-Ebola vaccines into clinical trials. While it's too early to say that any of the potential vaccines work, some scientists say they are seeing strong results from some of the studies. VOA's Carol Pearson reports.
Video

Video Philippines Wants Tourists Spending Money at New Casinos

Tourism is a multi-billion dollar industry in the Philippines. Close to five million foreign visitors traveled there last year, perhaps lured by the country’s tropical beaches. But Jason Strother reports from Manila that the country hopes to entice more travelers to stay indoors and spend money inside new casinos.
Video

Video Civilian Casualties Push Men to Join Rebels in Ukraine

The continued fighting in eastern Ukraine and the shelling of civilian neighborhoods seem to be pushing more men to join the separatist fighters. Many of the new recruits are residents of Ukraine made bitter by new grievances, as well as old. VOA's Patrick Wells reports.
Video

Video Islamic State Prisoners Talk of Curiosity, God, Regret

Islamic State fighter, a prisoner of Kurdish YPG forces, asked his family asking for forgiveness: "I destroyed myself and I destroyed them along with me." The Syrian youth was one of two detainees who spoke to VOA’s Kurdish Service about the path they chose; their names have been changed and identifying details obscured. VOA's Zana Omer reports.
Video

Video Germanwings Findings Raise Issue of Psychological Testing for Pilots

More is being discovered about the co-pilot in the crash of Germanwings Flight 9525 in the French Alps. Investigators say he was hiding a medical condition, raising questions about the mental qualifications of pilots. VOA's Carolyn Presutti reports.
Video

Video Liberia's Almost Last Ebola Patient Grateful but Still Grieving

Beatrice Yardolo was to make history as Liberia’s last Ebola patient. Liberians recently started counting down 42 days, the period that has to go by without a single new infection until the World Health Organization can declare a country Ebola-free. That countdown stopped on March 20 when there was another new case of Ebola, making Yardolo’s story a reminder that Ebola is far from over. Benno Muchler reports from Monrovia.
Video

Video Cambodian Land Grabs Threaten Traditional Communities

Indigenous communities in Cambodia's Ratanakiri province say the government’s economic land concession policy is taking away their land and traditional way of life, making many fear that their identity will soon be lost. Local authorities, though, have denied this is the case. VOA's Say Mony went to investigate and filed this report, narrated by Colin Lovett.

VOA Blogs

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More