Confusion Over Kepler's 'Earth-Like' Planets Explained
NASA's mini fiasco in public communication last
week was a scientist's attempt at public outreach gone awry. Kepler mission co-investigator Dimitar Sasselov of Harvard University, speaking at the
popular TED talks, tried to convey the excitement of hunting for Earth-size planets orbiting in the habitable zones of other stars. But his sloppy
terminology and careless graphics, says Kepler Principal Investigator William Borucki, led to headlines that Kepler had just discovered hundreds of
Earth-like planets. That's not true, says Borucki of NASA's Ames Research Center in Mountain View, California. "I'm disappointed one of our members
Sasselov's problems go back to his use of the term "Earth-like" in his 18-minute presentation
last month to a conference in Oxford, U.K.
"Kepler cannot tell whether [a candidate exoplanet] is Earth-like or not," notes Borucki. The orbiting telescope determines only an exoplanet's size
and, given more observing time, the distance from its star. " 'Earth-like' is a term common among astrophysicists," Borucki adds, "but it's not
appropriate for the public."
Compounding the confusion, Sasselov redrew a figure from a Kepler team manuscript and, in the process, inadvertently squeezed the majority of candidate
exoplanets into a size category he labeled "like Earth." But "there are no Earth-size planets in my figure," says Borucki, the manuscript's first
author. Look for the official release of the Kepler team's analysis of its most promising data next February. NASA's public affairs office should be
firmly in control by then.
Update: Sasselov's mea