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

1) An instrument for measuring the intensity of radiant energy in amounts as small as one millionth of an erg. It uses the change in resistance of a thin conductor caused by the heating effect of the radiation. → actinometer, → photometer, → pyrheliometer, → pyrometer, radiometer.
2) In astronomy, an instrument that measures the amount of radiant energy received from a celestial object.

From Gk. bole "stroke, beam of light," from ballein "to throw" + middle suffix -o- + → -meter..

Tafsanj, from taf "heat, warmth; light, brightness," from tâbidan, "→ radiate," + sanj, → -meter.