Question

About the AU and the LIGHT YEAR.

Answer 1

The astronomical unit (AU) is a unit of length, roughly the distance from Earth to the Sun. However, that distance varies as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once a year.

A light year is an unit of measurement that is defined as the distance travelled by light in one earth year. For example if a star is 4 light years away from earth it means that light from that star will take 4 years to reach earth.