from The American Heritage® Dictionary of the English Language, 4th Edition
- Sagan, Carl 1934-1996. American astronomer noted for research on the possibility of extraterrestrial life and for speculation on the severity of a nuclear winter. His books include Dragons of Eden (1977).
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A unit of measurement equal to at least four billion.
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. (Wiktionary)