AstrolinguisticsLincos languageNIROSETIPioneer plaqueProject CyclopsProject OzmaProject PhoenixSERENDIPSearch for extraterrestrial intelligenceSETI@homesetiQuestVoyager Golden RecordWater holeXenolinguisticsTypes of alleged extraterrestrial beingsEnergy beingsGrey aliensInsectoidsLittle green menNordic aliensReptilian humanoidsExhibitionsThe Science of AliensHypothesesCosmic pluralismDirected panspermiaDrake equationExtraterrestrial hypothesisFermi paradoxHypothetical types of biochemistryInterplanetary contaminationKardashev scaleMediocrity principlePanspermiaFermi paradox solutionsAestivation hypothesisBerserker hypothesisDark forest hypothesisFirstborn hypothesisGreat FilterHart–Tipler conjectureNeocatastrophismPlanetarium hypothesisRare Earth hypothesisZoo hypothesisRelated topicsAncient astronautsAstrobiologyAstroecologyBiosignatureBrookings ReportExotheologyExtraterrestrials in fictionExtremophileHemolithinMERMOZNexus for Ex