What is the exact, internationally agreed value for one Astronomical Unit (AU) in meters?
Answer
149,597,870,700 meters
Modern astronomy requires extreme precision, especially for navigation and trajectory planning for space missions. To eliminate the inherent uncertainties associated with historical observational estimates of Earth's orbit, the International Astronomical Union (IAU) established a modern, fixed definition for the Astronomical Unit. This precise constant value is exactly 149,597,870,700 meters. Prior to this standardization, the value was an approximation derived from observational geometry, but setting it as an exact integer number of meters ensures that all subsequent distance calculations, regardless of the instrument or time of measurement, begin from the exact same, unvarying foundational length.
Related Questions
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