Final answer:
The meter's initial definition relating to Earth's distance was changed to the length between engraved marks on a bar in 1889, redefined in 1960 using krypton light wavelengths, and refined in 1983 as the distance light travels in a vacuum in a specific fraction of a second.
Step-by-step explanation:
When French scientists first adopted the metric system, the real-world measurement they related to the definition of the meter was 1/10,000,000 of the distance from the equator to the North Pole. This distance was a practical representation of the Earth's size. The definition of meter was refined in 1889 to address the practical issues associated with the original definition, as well as to standardize a precise length that could be easily replicated. The meter was then redefined as the distance between two engraved lines on a platinum-iridium bar, housed near Paris. The real-world measurement used to refine the definition of meter in 1960 was 1,650,763.73 wavelengths of orange light emitted by krypton atoms. Finally, the latest advance in the definition of meter adopted in 1983 was the distance traveled by light in a vacuum in 1/299,792,458 of a second.