It may be a difficult number to verify, but NASA officials are saying that a batch of recently discovered planets prove that the universe is littered with hundreds of billions of planets similar those within our own solar system.
A new study finds that our own galaxy likely hosts upwards of 100 billion planets.
“There are at least 100 billion planets in the galaxy, just our galaxy,” says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal. “That’s mind-boggling.”
“It’s a staggering number, if you think about it,” adds Jonathan Swift, a postdoctoral student at Caltech and lead author of the paper. “Basically, there’s one of these planets per star.”
Swift and his colleagues arrived at their estimate after studying a five-planet system dubbed Kepler-32, which lies just under 1,000 light years from Earth. The team of NASA researchers say the alien solar system represents the vast majority of planets in our galaxy, thus serving as a perfect case study for understanding how most of these worlds form. The planetary system in question, which was detected by NASA’s Kepler space telescope, contains five planets. Two of the planets orbiting Kepler-32 had previously been discovered by other astronomers and at least one of the planets is thought to have a similar composition to that of Earth.
According to the NASA astronomers, systems similar to Kepler-32 comprise around three-quarters of all the stars in our galaxy, leading researchers to determine their 100 billion-planet estimate. The estimate could serve as a first step for astronomers focused on determining a solid figure for the number of planets throughout the universe.
“I usually try not to call things ‘Rosetta stones,’ but this is as close to a Rosetta stone as anything I’ve seen,” said Johnson. “It’s like unlocking a language that we’re trying to understand—the language of planet formation.”
While the study is far from definitive, it does represent the first attempt by astronomers to calculate the total number of planets based on actual observations made by NASA’s Kepler Space Telescope. The space telescope has reportedly captured images of upwards of 3,000 exoplanets, many of which have yet to be confirmed. Astronomers around the world have spent the last year and a half examining the images and conducting additional research to confirm their orbits and composition.
NASA’s Kepler Space Telescope, launched on March 6, 2009, searches for planet candidates orbiting distant suns, or exoplanets, by continuously measuring the brightness of more than 150,000 stars. When a planet candidate passes, or transits, in front of the star from the spacecraft’s vantage point, light from the star is blocked. Different sized planets block different amounts of starlight, allowing astronomers to determine a planet’s size relative to its star.
The announcement comes as Kepler is preparing for its extended mission. With the completion of the prime mission, Kepler now has collected enough data to begin finding true sun-Earth analogs — Earth-size planets with a one-year orbit around stars similar to the sun, said the U.S.-based space agency in a statement released in late 2012.
The new study was published January 2 in The Astrophysical Journal.