A zero to 10 scale which attempts to predict and categorize the effect of an announcement of the discovery of extraterrestial life. It was proposed in 2000 by Iván Almár and Jill Tarter at the 51st International Astronautical Congress. The IAA's SETI Committee (and its successor, the IAA SETI Permanent Study Group) officially adopted the Rio Scale in 2002. It has since been revised.
The scale is described at:
A Rio scale calculator is online at:
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Last revised: 14 September 2011.