An analysis of the Kepler spacecraft’s photographs of the of the 100 billion stars in the Earth’s galaxy found that 20 percent of the planets orbiting those stars have the potential to support life according to research conducted by University of California at Berkeley graduate student Erik Petigura, Geoffrey Marcy, University of California at Berkeley professor of astronomy, and Andrew Howard of the Institute for Astronomy at the University of Hawaii that was published in the Nov. 4, 2013, edition of the journal Proceedings of the National Academy of Sciences.
The closest Earth-like planet in the habitable zone of a star is only 12 light years from Earth and can be seen without the aid of a telescope.
The requirements for the development of life as it is known on Earth are water, a rocky surface, and carbon. Only one planet has been found that meets those requirements to date.
The researchers used the Keck telescope to examine the 42,000 stars found by the Kepler spacecraft that were similar in size and temperature to Earth’s sun to have the potential to support life. Of those stars, 603 had potentially habitable planets and ten of those planets had a similar distance from their star and the chemical combination necessary to support life.
The astronomers plan for future instrumentation that can more precisely determine the chemical composition of potentially life bearing planets that are similar to Earth.