This calculator /converter requires the use of Javascript enabled and capable browsers. This script creates an approximated conversion relationship in large distances within the realm of a solar system. Enter a value in any field; VERY large numbers are anticipated. The measurements are all uni-directional. NASA's definition of an Astronomical Unit (AU) is approximately the mean distance between the Earth and the Sun. It is a derived constant and used to indicate distances within the solar system. Its formal definition is the radius of an unperturbed circular orbit a massless body would revolve about the sun in 2*(pi)/k days (i.e. 365.2568983. days), where k is defined as the Gaussian constant exactly equal to 0.01720209895. Since an AU is based on radius of a circular orbit, one AU is actually slightly less than the average distance between the Earth and the Sun (approximately 150 million km or 93 million miles). Their definition of a light minute is the distance light travels in a vacuum in one minute, approximately 18 million kilometers; for a light hour, the distance light travels in a vacuum in one hour, approximately one billion kilometers. A light year is the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers. All are linear units used for astronomical distances.