1a.u=149597871
A light year is larger than an astronomical unit.
An astronomical unit (AU) is the mean distance from Earth to Sun, approximately 150 million km.
There are MANY units used to measure distances both in Metric and in English types. We use Feet and Yards to measure distances in the US. The academic field often uses metric units like meters and kilometers to measure distances. For larger or massive distances there are the units of miles (English) and Kilomiters (Metric) and then in space we have the Astonomical Unit (Distance from earth to Sun) and the Light Year for the biggest distances. And there are the smaller measures of inches and millimeters.
A light year.
As far as I am aware, CO is not a unit of measure.
A unit can be a measure of length. It is one-dimensional. A squared unit can be a measure of area. It is two-dimensional. A cubic unit can be a measure of volume. It is three-dimensional.
This depends on what unit you are using to measure in. However, area will always be measure in (unit)^2.
The international (SI) unit of mass is the kilogram.
The measure unit of a kilometer stick is kilometer.
division
The 'ERG' is the standard unit for work or mechanical energy.
Hertz, hz= 1/second is the unit measure of frequency.