<P> The astronomical unit ( symbol : au or ua ) 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 . Originally conceived as the average of Earth 's aphelion and perihelion , it is now defined as exactly 7011149597870700000 ♠ 149 597 870 700 metres ( about 150 million kilometres , or 93 million miles ) . The astronomical unit is used primarily as a convenient yardstick for measuring distances within the Solar System or around other stars . However , it is also a fundamental component in the definition of another unit of astronomical length , the parsec . </P>
<P> The astronomical unit ( symbol : au or ua ) 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 . Originally conceived as the average of Earth 's aphelion and perihelion , it is now defined as exactly 7011149597870700000 ♠ 149 597 870 700 metres ( about 150 million kilometres , or 93 million miles ) . The astronomical unit is used primarily as a convenient yardstick for measuring distances within the Solar System or around other stars . However , it is also a fundamental component in the definition of another unit of astronomical length , the parsec . </P>
average distance from earth to sun in kilometers
average distance from earth to sun in kilometers
about 150 million
about 150 million