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

1) A cylinder or block of wax, tallow, or other fatty substance with a central wick, which is burned to produce light.
2) A unit of luminous intensity, superseded by the → candela.

M.E., O.E. candel, from L. candela "a light, torch," from candere "to shine," candidus "shining white" (E. candidate); cf. Skt. cand- "to shine, to glow," candati "shines," candra- "shining, glowing, the Moon;" Gk. kandaros "coal;" PIE base *kand- "to glow, to shine."

Šam', loan from Ar.

An astronomical object, belonging to some class, that has a known luminosity. In principle, by comparing the known luminosity to the observed brightness, the distance to the object can be derived. The four major primary distance indicators are Cepheids, supernovae, novae, and RR Lyrae variables. The secondary distance indicators include H II regions, globular clusters, brightest red and blue stars. → primary calibrator; → secondary calibrator.

→ standard; → candle.