Earth-Like Planets Quite Common
Many people wonder how unique Earth and the other planets of the Solar System are as other Earth-like planets may also have life on it, similar to what we find around us. Finding these other planets is not easy, but those researchers hunting for them are having some success. Researchers at the Harvard-Smithsonian Center for Astrophysics have recently released an analysis that indicates one in six, or 17%, of all stars should have an Earth-like planet orbiting them, and 70% should have a planet of any size.
The researchers used NASA's Kepler spacecraft for their planet hunting. It watches for the regular dimming of a star caused by a planet crossing in front of it, and while this method does work, it has its limitations. Primarily it is limited by the size of a planet and distance it is from its star, so those Earth-like planets around 17% of stars are also in an orbit closer than Mercury. For Kepler to catch a planet at an Earth-sized orbit, the planet would have to be a gas giant, or the spacecraft would have to observe the star for a very long time to observe the minor eclipsing a smaller planet would cause.
Another result of this research actual upends previous findings concerning other planetary systems. The researchers failed to find any correlation between the size of the host star and the size of the planets, except for gas giants. Planets of smaller sizes were found equally around stars similar to the Sun and much smaller Red Dwarfs.