It refers to the experience of seeing firsthand the reality of the Earth in space, which is immediately understood to be a tiny, fragile ball of life, "hanging in the void", shielded and nourished by a paper-thin atmosphere. From space, national boundaries vanish, the conflicts that divide people become less important, and the need to create a planetary society with the united will to protect this "pale blue dot" becomes both obvious and imperative.
Third-hand observers of these individuals may also report a noticeable difference in attitude. Astronauts Ron Garan (Ted Talk on youtube: TedxVienna - Ron Garan - The Orbital Perspective of Our Fragile Oasis) Rusty Schweikart, Edgar Mitchell, Tom Jones, and Mike Massimino are all reported to have experienced the effect.
The term and concept were coined in 1987 by Frank White, who explored the theme in his book The Overview Effect — Space Exploration and Human Evolution (Houghton-Mifflin, 1987), (AIAA, 1998). The overview effect has been considered to be one of the stimuli that led to the Gaia hypothesis.
An article claims the environmental protection movement was inspired by NASA's Earthrise (and another) photograph.
- National Aeronautics and Space Administration; Douglas A. Vakoch (6 July 2011). Psychology of Space Exploration: Contemporary Research in Historical Perspective. Government Printing Office. pp. 29–. ISBN 978-0-16-088358-3. Retrieved 9 February 2013.
- Albert A. Harrison (1 April 2007). Starstruck: Cosmic Visions in Science, Religion, and Folklore. Berghahn Books. pp. 92–. ISBN 978-1-84545-286-5. Retrieved 9 February 2013.
- Douglas A. Vakoch. On Orbit and Beyond. Springer. pp. 10–. ISBN 978-3-642-30583-2. Retrieved 9 February 2013.
- "Space Euphoria: Do Our Brains Change When We Travel in Outer Space?", Daily Galaxy, 2008-05-20
- The Human Brain in Space: Euphoria and the “Overview Effect” Experienced by Astronauts, Ian O'Neill, Universe Today, 2008-05-22
- "StarTalk Live at the Bell House, The Astronaut Session", Star Talk Radio, 2012-01-29, 
- "Space Tourism: Face Time with Earth", Leonard David, Senior Space Writer, SPACE.com, 2006-08-05, Space-ecotourism
- "Earthrise: The Photo that Launched a Movement". TreeHugger. Retrieved 2015-11-05.