Astronomical unit (in metres)
m
The astronomical unit in metres — the exact SI value of the Earth–Sun mean distance, fixed by definition since 2012. It is the standard length unit for solar-system astronomy.
Used in
- Solar-system distance scale (Neptune ≈ 30 au)
- Parsec definition: 1 pc = 1 au / 1 arcsecond
Source: SI defining constants / CODATA 2018