Kilometre

The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; /ˈkɪləmiːtə/ or /kɪˈlɒmɪtə/) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 7003100000000000000♠1000). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.

k (pronounced /keɪ/) is occasionally used in some English-speaking countries as an alternative for the word kilometre in colloquial writing and speech. A slang term for the kilometre in the US military is klick.

Pronunciation

There are two common pronunciations for the word.

The former follows a pattern in English whereby metric units are pronounced with the stress on the first syllable, and the pronunciation of the actual base unit does not change irrespective of the prefix. It is generally preferred by the British Broadcasting Corporation (BBC) and the Australian Broadcasting Corporation (ABC).

Marathon

The marathon is a long-distance running event with an official distance of 42.195 kilometres (26.21875 miles, or 26 miles 385 yards), usually run as a road race. The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon to Athens.

The marathon was one of the original modern Olympic events in 1896, though the distance did not become standardized until 1921. More than 500 marathons are held throughout the world each year, with the vast majority of competitors being recreational athletes as larger marathons can have tens of thousands of participants.

History

Origin

The name Marathon comes from the legend of Pheidippides, a Greek messenger. The legend states that he was sent from the battlefield of Marathon to Athens to announce that the Persians had been defeated in the Battle of Marathon (in which he had just fought), which took place in August or September, 490 BC. It is said that he ran the entire distance without stopping and burst into the assembly, exclaiming νενικήκαμεν (nenikekamen, "we have wοn"), before collapsing and dying. The account of the run from Marathon to Athens first appears in Plutarch's On the Glory of Athens in the 1st century AD, which quotes from Heraclides Ponticus's lost work, giving the runner's name as either Thersipus of Erchius or Eucles.Lucian of Samosata (2nd century AD) also gives the story, but names the runner Philippides (not Pheidippides).

100 kilometres

A length of 100 kilometers (about 62 English miles), as a rough amount, is relatively common in measurements on Earth and for some astronomical objects. It is the altitude at which the FAI defines spaceflight to begin. To help compare orders of magnitude, this page lists lengths between 100 and 1,000 kilometres (10⁵ and 10⁶metres).

Distances shorter than 100 kilometres

Conversions

A distance of 100 kilometres is equal to about 62 miles (or 62.13711922 miles).

Human-defined scales and structures