Billions and billions of Earth-sized planets call Milky Way home

The galaxy contains billions of potentially habitable Earth-sized planets, according to even the most conservative estimate drawing on data from NASA’s Kepler space telescope.
Although a mechanical failure recently put the telescope out of commission (SN: 6/15/13, p. 10), Kepler’s census of planets orbiting roughly 170,000 stars is enabling astronomers to predict how common planets similar to Earth are across the galaxy