An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A layer of soft, partly molten, rock in the → Earth's mantle, located at a depth of 100 to 250 km, over which the more rigid plates of the → lithosphere are in motion.

Asthenosphere, from Gk. asthenes "weak" + → sphere.

Sostsepehr, from sost "weak, tender" + sepehr, → sphere.