太阳仪
Heliometer \He`li*om"e*ter\, n. [Helio- + -meter: cf. F. h['e]liom[`e]tre.] (Astron.) 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.