Meter

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

1. The meter is crucial for measuring distances between celestial objects.
2. Astronomers often convert meters to astronomical units or light-years for practicality.
3. One meter equals approximately 39.37 inches.
4. Meters are used to establish baselines for larger units like kilometers and parsecs.
5. The definition of a meter was redefined in terms of the speed of light in 1983.

Review Questions

• How is a meter defined in terms of the speed of light?
• Why do astronomers need to convert meters to other units like astronomical units or light-years?
• When was the current definition of a meter established?

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.

parsec: A parsec is a unit of distance used in astronomy, equal to about 3.26 light-years or approximately 31 trillion kilometers.