Glossary term: Extraterrestrial Intelligence

Description: Extraterrestrial intelligence refers to the possible existence of intelligent entities other than those on Earth.

Searches for extraterrestrial intelligence have included looking for radio or other signals, but much current research is centered on determining whether the conditions for intelligent life are present elsewhere. Going by the available evidence, the necessary conditions for the emergence of life on Earth – a solid planet, at a distance from its star where liquid water can exist on the planet's surface, atoms like carbon and oxygen, and the conditions to form more complex molecules – should exist on numerous other planets within our Galaxy and beyond. It is not an unreasonable assumption that intelligent life might have arisen at least on some of those planets, although we have no solid basis for estimating the probability of that happening.

Some astronomers have used radio signals to search for putative messages as part of a Search for Extraterrestrial Intelligence (SETI). The speed of light as a fundamental physical limit means that interstellar journeys would take very long times, limiting the ability for us to come into direct contact with extraterrestrial intelligences.

Related Terms:

See this term in other languages

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".