Eighty - Definition and Overview

80 is the natural number following 79 and preceding 81.

• Greek numeral: π´
• See wiktionary:eighty to see 80 in other languages.

In mathematics

80 is a Harshad number

In science

• The atomic number of mercury

In astronomy,

Messier object M80, a magnitude 8.5 globular cluster in the constellation Scorpius

The New General Catalogue object (http://www.ngcic.org/) NGC 80, a magnitude 12.1 spiral galaxy in the constellation Andromeda

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -333 June 13 and ended on 929 July 9. The duration of Saros series 80 was 1262.1 years, and it contained 71 solar eclipses.

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -121 January 27 and ended on 1213 April 6. The duration of Saros series 80 was 1334.2 years, and it contained 75 lunar eclipses.

In other fields

Eighty is also:

• the number of units in a fourscore
• the age at which one becomes an octogenarian
• in the title of Around the World in Eighty Days by Jules Verne
• the model number of the computers TRS-80, IBM 80, Sinclair ZX80, and Aster CT-80
• the model number of:
  • T-80, a Soviet tank
  • IAR 80, a Romanian WWII fighter aircraft
  • McDonnell Douglas MD-80, Arado Ar 80, and F-80 Shooting Star
• part of the name of the bands Eighty-D and Eighty Proof Soul
• the age limit for cardinals to vote in papal elections
• the percentage of work done with 20% of the resources according to a "80-20 rule"
• the length of a beach in Western Australia: Eighty Mile Beach
• the length of the Eighty Years' War or Dutch revolt (1568-1648)
• the number of the French department Somme
  
• the designation of Interstate 80, a freeway that runs from California to New Jersey; the European route E80 from Lisbon to Gürbulak
• the standard TCP/IP port number for HTTP connection
• the 80A, 80B and 80C photographic filters correct for excessive redness under tungsten lighting
• The ISBN Group Identifier for books published in the Czech Republic and Slovakia.
• The year AD 80, 80 BC, or 1980.