The astronomical unit (symbol: au[1][2][3][4] or AU) is a unit of length defined to be exactly equal to 149 597 870 700 m. [5] Historically, the astronomical unit was conceived as the average Earth - Sun distance (the average of Earth 's aphelion and perihelion), before its modern redefinition in 2012. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical ... Learn how astronomers measure the distance between Earth and the sun using one astronomical unit (AU), and how it varies throughout the year. Compare AU with other units of space measurement, such as light-year and parsec, and explore the solar system in AU. Learn the average and variable distance between Earth and the Sun , and how it affects seasons and orbits. Find out the history and methods of measuring the distance , and the new definition of the astronomical unit. Calculate Earth 's distance from the Sun with our solar distance calculator. See live AU, km, and mile measurements with orbital visualization and perihelion/aphelion tracking.
