Extraterrestrial, EHKS truh tuh REHS tree uhl, intelligence is intelligent life that developed somewhere other than the earth. No life has been discovered on any planet other than the earth. However, many scientists have concluded that intelligent life may exist on planets orbiting some of the hundreds of billions of stars in our galaxy, the Milky Way. These scientists base their conclusion on research in such fields as astronomy, biology, planetary science, and paleontology (the study of prehistoric life through fossils). The effort to find evidence that there is extraterrestrial intelligence is often called SETI, which stands for Search for Extraterrestrial Intelligence.