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:
“Consider the China pride and stagnant self-complacency of mankind. This generation inclines a little to congratulate itself on being the last of an illustrious line; and in Boston and London and Paris and Rome, thinking of its long descent, it speaks of its progress in art and science and literature with satisfaction.... It is the good Adam contemplating his own virtue.”
—Henry David Thoreau (1817–1862)
“It is impossible to dissociate language from science or science from language, because every natural science always involves three things: the sequence of phenomena on which the science is based; the abstract concepts which call these phenomena to mind; and the words in which the concepts are expressed. To call forth a concept, a word is needed; to portray a phenomenon, a concept is needed. All three mirror one and the same reality.”
—Antoine Lavoisier (1743–1794)