“Astronomical Unit,” or Earth-Sun Distance, Gets an Overhaul
A new AU redefinition involves changing it to a single number rather than basing it on a somewhat baffling equation.
Without fanfare, astronomers have redefined one of the most important distances in the Solar System. The astronomical unit (au) — the rough distance from the Earth to the Sun — has been transformed from a confusing calculation into a single number. The new standard, adopted in August by unanimous vote at the International Astronomical Union’s meeting in Beijing, China, is now 149,597,870,700 meters — no more, no less.