Well-defined Numbers That Are Not Precisely Known
Sagan's number is the number of stars in the observable universe. It is named in honor of Carl Sagan. This number is reasonably well defined, since we know what stars are and what the observable universe is, but its value is not known with any certainty (it is presently estimated to be approximately 70 sextillion (short scale)).
Sagan's number is unrelated to the bogus sagan unit or the humorous use of the term "sagan" to denote any large quantity.
Read more about this topic: Indefinite And Fictitious Large Numbers
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