In Science
- The atomic number of protactinium, an actinide.
- McCarthy 91 function, a recursive function in discrete mathematics
In astronomy,
- Messier object M91, a magnitude 11.5 spiral galaxy in the constellation Coma Berenices
- The New General Catalogue object NGC 91, a single star in the constellation Andromeda
- The Saros number of the solar eclipse series which began on August 6, 159 BC and ended on 1175 October. The duration of Saros series 91 was 1334.2 years, and it contained 75 solar eclipses.
- The Saros number of the lunar eclipse series which began on 161 May and ended on 1459 July. The duration of Saros series 91 was 1298.1 years, and it contained 73 lunar eclipses.
Read more about this topic: 91 (number)
Famous quotes containing the word science:
“Art is the beautiful way of doing things. Science is the effective way of doing things. Business is the economic way of doing things.”
—Elbert Hubbard (1856–1915)
“If science fiction is the mythology of modern technology, then its myth is tragic.”
—Ursula K. Le Guin (b. 1929)