heliometer
noun
Forms heliometers
- noun An astronomical instrument, based on a telescope, for measuring the diameter of the sun; now used to measure the angular distance between stars and other celestial bodies.
Etymology
From helio- + -meter, from Ancient Greek Ἥλιος (Hḗlios), from ἥλιος (hḗlios, “sun”), and French mètre, from Ancient Greek μέτρον (métron, “measure”).
Webster’s 1913
- noun An instrument devised originally for measuring the diameter of the sun; now employed for delicate measurements of the distance and relative direction of two stars too far apart to be easily measured in the field of view of an ordinary telescope.
Etymology [Helio- + -meter: cf. F. héliomètre.]
Sources: Wiktionary · Webster’s 1913 — from the Wiktionary entry “heliometer”, CC BY-SA 4.0. Details