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

1) Sending out rays of light; bright; shining.
See also: → radiant energy, → radiant flux, → radiant intensity.
2) The point in the sky from which → meteors in a → meteor shower appear to radiate or come. See also: → radiant drift.

M.E., from M.Fr. radiant, from L. radiantem (nominative radians) "shining," pr.p. of radiare "to shine, radiate," → radiation.

1) Tâbandé, tâbeši adj. from tâbidan, → radiate.
2) Tâbsar, from tâb "light, radiation," → radiation, + sar "head, top, summit, point," → head.

The apparent slow motion of the → radiant of a → meteor shower from night to night against the background stars due to the Earth moving in its orbit around the Sun.

→ radiant; → drift.

The energy that is transmitted in the form of → radiation, in particular as → electromagnetic radiation.

→ radiant; → energy.

Rate of flow of energy as → radiation.

→ radiant; → flux.

A measure of the amount of radiation emitted from a point expressed as the radiant flux per unit solid angle leaving this source.

→ radiant; → intensity.