Stars have songs trapped in their hearts, according to William Chaplin. The resonating sounds found within a star, he says, make it quake and pulse in tiny but predictable ways, that could help astronomers in their search for Sun-sized starts that shelter Earth-sized planets.

We could guess the size of a piccolo or a tuba hidden behind the orchestra curtain by their sounds alone, the University of Birmingham physicist suggested, and the same is generally true for stars. "The bigger the star, the deeper the 'tone' or oscillations it gives off," Chaplin said at the 2011 AAAS Annual Meeting.

Chaplin's research in the new field of asteroseismology is one of the lesser-known highlights of the NASA Kepler mission, a space-based telescope launched in 2009 to explore a portion of the Milky Way galaxy for Earth-like planets. At the Annual Meeting, Kepler researchers discussed the data gleaned by the telescope in its first years, surveying its designated patch of sky in the constellations Cygnus and Lyra.

The telescope measures the brightness of nearly 100,000 stars every 30 minutes, watching for small flickers in their brightness as possible planets move between the telescope and the star.  Kepler has helped detect about 1200 "candidate" planets so far, said NASA space scientist William Borucki, including 68 that are similar in size to Earth.

Pretender planets can be dethroned with further observations from ground-based telescopes, which can help astronomers check off a list of "astronomical false positives" such as the presence of a binary star that could be mistaken for a new world, said Matthew Holman, a Kepler researcher from the Harvard-Smithsonian Center for Astrophysics.

Confirmation could also come from new data downloaded from Kepler after the planet slips between its star and the telescope again. But these transits are difficult to catch, and Borucki said many decisions on planethood could be postponed until 2012, when the telescope has captured enough transit data.

In the meantime, the Kepler team has plenty of pondering about these possible worlds to keep them occupied. Among Kepler's finds, said MIT planet scientist Sara Seager, are a hot rocky planet that may be covered in lakes of lava, a hot but unexpected bright planet the size of Jupiter, and a spectacular collection of six rock and gas planets orbiting in nearly the same place around their star.

"By now, we're used to expecting the unexpected," she said.

For more details on the Kepler mission and the possibility of nearby Earth-like planets, read a transcript of the Science News team's Live@AAAS chat with Borucki and Seager.