The unit is derived from the phrase billions and billions (of stars), frequently attributed to the American astronomer Carl Sagan. The lower bound of a number must be two billion plus two billion, or four billion. Johnny Carson popularized the phrase through his occasional impersonation of Sagan throughout his career.
Sagan (plural Sagans)
- Sagan at dictionary.reference.com (Jargon File)
- William Safire, ON LANGUAGE; Footprints on the Infobahn, New York Times, April 17, 1994
- Carl Sagan, Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium, Random House, 1997