Humans long believed that there were other planets out in space, circling around distant stars. Scientists just never knew where to look for them. In the past 20 years all that has changed. Today, astronomers have confirmed more than 900 extra-solar (outside of our solar system) planets, and the number continues to climb. Some astronomers think that there are at least 100 billion planets in our galaxy alone. These planets come in a variety of sizes, temperatures, and orbits. Many have detected so far are giants like Jupiter and Saturn- but this is mostly because these are easier to spot. Big observatories on Earth and orbiting telescopes have also found small, rocky planets, boiling hot planets, iceball planets, systems with nine planets, planets around double stars, planets around red giant stars, and even lonely wandering planets without a star. The great prize for planet finders, though, will be an Earthlike, Earth-size planet in the "habitable zone." This is an orbit that keeps a planet warm enough to hold liquid water on its surface- and maybe to host life. Scientists are now beginning to identify some candidates. Will there be life of them? Stay tuned!