Written by the Fiveable Content Team โข Last updated September 2025
Written by the Fiveable Content Team โข Last updated September 2025
Definition
A meter is the fundamental unit of length in the International System of Units (SI). It is defined as the distance light travels in a vacuum in 1/299,792,458 seconds.
5 Must Know Facts For Your Next Test
The meter is crucial for measuring distances between celestial objects.
Astronomers often convert meters to astronomical units or light-years for practicality.
One meter equals approximately 39.37 inches.
Meters are used to establish baselines for larger units like kilometers and parsecs.
The definition of a meter was redefined in terms of the speed of light in 1983.
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Related terms
astronomical_unit: An astronomical unit (AU) is approximately the average distance between Earth and the Sun, about 149.6 million kilometers.
light_year: A light-year is the distance that light travels in one year, roughly equivalent to 9.46 trillion kilometers.