By DENNIS OVERBYE
Published: August 2, 2010
Dimitar Sasselov, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, lit up the Internet last month with a statement that would stir the soul of anyone who ever dreamed of finding life or another home in the stars.
Brandishing data from NASA’s Kepler planet-finding satellite, during a talk at TED Global 2010 in Oxford on July 16, Dr. Sasselov said the mission had discovered 140 Earthlike planets in a small patch of sky in the constellation Cygnus that Kepler has been surveying for the last year and a half.
“The next step after Kepler will be to study the atmospheres of the planets and see if we can find any signs of life,” he said.
Last week, Dr. Sasselov was busy eating his words. In a series of messages posted on the Kepler Web site Dr. Sasselov acknowledged that should have said “Earth-sized,” meaning a rocky body less than three times the diameter of our own planet, rather than “Earthlike,” with its connotations of oxygenated vistas of blue and green. He was speaking in geophysics jargon, he explained.
And he should have called them “candidates” instead of planets.
“The Kepler mission is designed to discover Earth-sized planets but it has not yet discovered any; at this time we have found only planet candidates,” he wrote……………………