One in five stars has Earth-sized planet (1)

A team of researchers from University of California at Berkeley and University of Hawaii, Manoa, released a study that looks at how common Earth-size planets are around stars that are more like our sun.    Image © Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley.

They determined that twenty percent of Sun-like stars in our galaxy have Earth-sized exoplanets that could host life, within the habitable zone.



The habitable zone area where planets receive the same amount of stellar energy, as the Earth receives from the Sun.

Geoff Marcy, a Berkeley astronomer and co-author of the research paper, said:

“Earth-sized planets having the temperature of a cup of tea are common around sunlike stars. This represents one great leap toward the possibility of life, including intelligent life, in the universe.”

One in five stars has Earth-sized planet (2)

Credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley.

“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. That is amazing,” said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler and Keck Observatory data.



“For NASA, this number – that every fifth star has a planet somewhat like Earth – is really important, because successor missions to Kepler will try to take an actual picture of a planet, and the size of the telescope they have to build depends on how close the nearest Earth-size planets are,” said Andrew Howard, astronomer with the Institute for Astronomy at the University of Hawaii. “An abundance of planets orbiting nearby stars simplifies such follow-up missions.”

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

Read more W.M. Keck Observatory,   PNAS