# What is *length*?

**Length**is a measure of distance. The length of something is the distance between its two ends. Small length is called short and big length is called long. For two or three dimensional things, length is usually the longest side or edge.

## Input

**Meter**is the base unit of length in the International System of Units (SI).

## Output

**Astronomical Unit**is roughly the distance from Earth to the Sun. The actual distance varies as Earth orbits the Sun. However, since 2012 it has been defined as exactly 149 597 870 700 meters.