astronomical unit (au) یکای ِ اخترشناسیک، ~ اخترشناختی yekâ-ye axtaršenâsik, ~ axtaršenâxti (#) Fr.: unité astronomique A unit of length equal to 149 597 870 700 m exactly, with symbol “au”
(re-definition at the International Astronomical Union’s 28th General
Assembly in Beijing, China, August 20-31). The astronomical unit equals
1.5813 × 10-5 → light-years and
4.8481 ×10-6 → parsecs.
Previous definition: The radius of a circular orbit in which a body of
negligible mass, and free of perturbations, would revolve around the Sun in
2 π / k days, where k is the
→ Gaussian gravitational constant. This is slightly
less than the semi-major axis of the Earth’s orbit.
See also: → astronomical; → unit. |
