Extraterrestrial life.Biochemistry,Hypothetical types of biochemistry,Cosmic pluralism,Drake equation,Zecharia Sitchin,Panspermia,Sentience quotient,Snaiad,Kardashev scale,Cryptozoology,Astrobiology,Planetary habitability,Extrasolar planet,Life on Mars,Wow! signal,Extraterrestrial liquid water,Scientific skepticism,Gliese 581 c,Ceres (dwarf planet),Gliese 581 d,SETI,OGLE-2005-BLG-390Lb,Gliese 581,Allan Hills 84001,NASA,Kepler Mission,Terrestrial Planet Finder,Communication with Extraterrestrial Intelligence