Cum s-a masurat Ecuatorul si de catre cine a fost masurat? Mersi.

Sper ca stii engleza...

== Exact length ==
In two widely used [[geodesy|geodetic]] standards, the Equator is modelled as a circle whose radius is a [[integer|whole number]] of metres. In 1976 the [[International Astronomical Union|IAU]] chose a radius of {{convert|6378.140|km}}, later refined by the [[International Union of Geodesy and Geophysics|IUGG]] to {{convert|6378.137|km}} and adopted in [[World Geodetic System|WGS-84]], though the yet more recent IAU-2000 has retained the old IAU-1976 value. If it were really circular the length of the Equator would be exactly 2π times the assumed radius.

The [[geographical mile]] is defined as one arc minute of the Equator, so it has different values depending on which radius is assumed, e.g. {{convert|1855. 3248|m}} for WGS84 or {{convert|1855. 3257|m}} for IAU-2000.

The earth is modelled commonly as a sphere flattened 0.336% along its axis. This makes the Equator 0.16% longer than a [[Meridian (geography)|meridian]] (a great circle passing through the two poles). The IUGG standard meridian is, to the nearest millimetre, {{convert|40007. 862917|km}}, one arc minute of which is {{convert|1852.216|m}}, explaining the [[International System of Units|SI]] standardization of the [[nautical mile]] as {{convert|1852|m}}, more than {{convert|3|m}} less than the [[geographical mile]].

The sea-level surface of the Earth (the [[geoid]]) is irregular, so the actual length of the Equator is not so easy to determine. ''Aviation Week and Space Technology'' on 9 October 1961 reported that measurements using the Transit IV-A satellite had shown the equatorial "diameter" from longitude 11° West to 169° East to be {{convert|1000|ft}} greater than its "diameter" ninety degrees away.{{citation needed|date=March 2012}}


http://en.wikipedia.org/wiki/Equator