Astrobiology: The study of the living universe

Christopher F. Chyba, Kevin P. Hand

Research output: Contribution to journalArticlepeer-review

116 Scopus citations


Astrobiology is the study of the living universe. Astronomy provides the context for the origin and evolution of life on Earth. Conversely, discoveries about the terrestrial biosphere-from extremophilic microbes to the evolution of intelligence - inform our thinking about prospects for life elsewhere. Astrobiology includes the search for extraterrestrial life via in situ exploration, spectroscopy of solar and extrasolar planetary atmospheres, and the search for extraterrestrial intelligence. This review situates astrobiology within philosophical issues of the definition of life and the biological compatibility of the universe. It reviews the habitability of the Galaxy in general and of planets and moons in particular, and summarizes current controversies in origins-of-life research and in evidence for the earliest life on Earth. It critiques certain "rare Earth" and "anthropic" arguments, and considers four approaches to deciding whether intelligent life exists elsewhere in the Galaxy. It concludes that astrobiology must also speak to the future of human civilization.

Original languageEnglish (US)
Pages (from-to)31-74
Number of pages44
JournalAnnual Review of Astronomy and Astrophysics
StatePublished - 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Bioastronomy
  • Cosmobiology
  • Exobiology
  • SETI


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