Seth Shostak is an American astronomer, author, and science communicator who has spent decades with the SETI Institute. His research and public work focus on radio searches for technological civilizations, the probability of life elsewhere, and the practical problem of distinguishing a genuine signal from interference and natural phenomena.

Shostak trained in radio astronomy and used large arrays to study galaxies before joining the SETI Institute. He later became one of the organization’s most recognizable public voices through books, lectures, articles, and the radio program Big Picture Science. That career centers on explaining how an actual search is designed: choose detectable signals, survey systematically, and follow up candidates. His skepticism of visitation claims grows from decades spent trying to turn the broad possibility of alien intelligence into a specific observing program.

Shostak regards extraterrestrial life as scientifically plausible and worth searching for, but he has repeatedly argued that UFO reports have not produced the kind of independently verifiable evidence needed to establish visitation. He contrasts a repeatable astronomical signal with ambiguous imagery, eyewitness testimony, or claims whose underlying data remain classified. UAP advocates sometimes view that standard as too dismissive of military cases; Shostak sees it as the minimum needed for a discovery of historic scale.

Shostak’s SETI career made him a prominent scientific interpreter of claims about non-human intelligence. He explains how signal searches handle false positives, repeatability, and independent confirmation, then applies that experience to public discussion of UAP. His role is not military case investigation but clarifying how a culturally compelling possibility would become an accepted scientific discovery.