It is the distance of the extension of what your eyes can see. If the earth wasn't formed, there can be no possibility of measuring distances to or from it.
An Astronomical Unit is the distance between Earth and the Sun and is used as a measurement unit for measuring the distances of other objects from Earth.
Different units for measuring distance are: 1.for distances on earth miles , kilometer, meter 2. Between galaxies - light year.
about 10,000000km
Map scale
An AU is much larger than any distance on Earth. Earth's equatorial circumference is about 0.00027 . So measuring distances on Earth in AU would be like measuring the sizes of small animals in miles.
Distances between stars are not measured in miles: that is like measuring the distance from the Earth to the Sun in thousandths of an inch! However, since you asked, Rigel is approx 5 quadrillion miles away.
A map scale.
A map scale.
Gravity
AU is not used to measure the distances on earth, because a astronomical unit is a unit of measurement equal to the distance between Earth and Sun. So that's why you cannot use Au for measure the distances on Earth.
Gravity