In 1960, the meter was again redefined, this time in terms of a certain number of wavelengths of a certain emission line of krypton-86. This changed in 1889, when the International prototype metre was established as the length of a prototype meter bar (made of an alloy of 90% platinum and 10% iridium) measured at the melting point of ice. History/origin: Originally, in 1793, the meter was defined as one ten-millionth of the distance from the equator to the North Pole. This definition was slightly modified in 2019 to reflect changes in the definition of the second.
The meter is defined as the distance traveled by light in 1/299 792 458 of a second.
Definition: A meter, or metre (symbol: m), is the base unit of length and distance in the International System of Units (SI).
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