NASA launched the Kepler Space Telescope in March 2009 to give astronomers an idea about how many planets might exist out there in the depths of space. Unlike other telescopes, Kepler doesn't look at different parts of the sky; it focuses on one patch of space and surveys the same stars over and over. The telescope is looking for the regular dimming of the stars, which can indicate that a planet has passed between the Earth and that star. Scientists call that a "transiting" planet.
So far, Kepler's spotted 1,235 possible transiting planets, including 54 that are in what scientists call the habitable zone. They estimate that those planets are at the right distance from their respective stars to have liquid water, which is a requirement for all life that we know. They are all shown in the graphic above.
Below the top row of huge stars, you can see our own sun at scale. Both Jupiter and Earth are shown transiting, but Earth is just the tiniest speck.
So far, only 15 of these possible planets have been confirmed as discoveries by ground-based telescopes.