New Earth-like planets

About one in four stars similar to our Sun may host planets as Earth. That is according to a new study funded by NASA and University of California and published by Science.

"Earth-size planets in our galaxy are like grains of sand sprinkled on a beach -- they are everywhere" said Andrew Howard of the University of California, Berkeley, lead author of the new study (in a common news release of the Jet Propulsion Laboratory in Pasadena, California, and NASA Headquarters in Washington, DC).

His team looked for planets within 80-light-years of Earth, using the radial velocity, or "wobble," technique. To measure the minute wobble of each star astronomers have used the 10-meter Keck telescopes in Hawaii (instrument operated by the University of California and Caltech).

"Of about 100 typical Sun-like stars, one or two have planets the size of Jupiter, roughly six have a planet the size of Neptune, and about 12 have super-Earths between three and 10 Earth masses," said also Andrew Howard, a research astronomer in UC Berkeley's Department of Astronomy and at the Space Sciences Laboratory (in a press release of the University of California, Berkeley).

He adds that "if we extrapolate down to Earth-size planets -- between one-half and two times the mass of Earth -- we predict that you'd find about 23 for every 100 stars."

For more information about exoplanets and NASA's planet-finding program click here.