A major advance in human understanding of our universe occurred in 1995, when we entered the era of the discovery of planetary systems around stars other than the Sun. Roughly 300 planets have been found outside our Solar System to date, ranging from the fairly familiar to the weirdly unexpected. Nearly all of the new planets discovered so far appear to be gas giant planets, similar to our Jupiter and Saturn. In the last few years, however, over a dozen planets have been discovered with much lower masses, in the range of 5 to 20 times the mass of the Earth, masses that are comparable to those of the ice giant planets in our Solar System, Uranus and Neptune. However, but it is not yet clear if these smaller mass planets truly are ice giant planets, or are perhaps rocky planets similar in composition to the Earth, but with much more mass, i.e., super-Earths. The latter possibility would be tantalizing evidence that Earths are common. The long-term goal is to discover and characterize nearby Earth-like, habitable planets. European space agencies and NASA have launched and planned an array of space-based telescopes that will carry out this incredible search in the next several decades. The French-led CoRoT Mission and NASA's Kepler Mission will search for evidence of Earth-mass planets by the transit technique, where the presence of the planet is inferred by monitoring the tiny dimming of star light caused by passage of the planet in front of the star it is orbiting. CoRoT and Kepler are likely to provide our first firm estimates of the frequency of habitable, Earth-like planets in our neighborhood of the galaxy. Once that frequency is known, we will know how best to design specialized space telescopes that will be capable of imaging these new worlds, and telling us whether their atmospheres show evidence of the molecules necessary for life (e.g., water and oxygen), and possibly even those created by life (e.g., methane). We will then know if any of the nearby stars harbor planets that are habitable, and perhaps even inhabited. We will know just how crowded the universe really is.