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

To perceive with the eyes; look at.

M.E. seen, from O.E. seon "to see, look, behold, understand, know," ultimately from PIE *sek^w- "to see, notice;" cognate with Du. zien "to see," Ger. sehen "to see," Danish, Swedish and Norwegian Bokmal se "to see," L. signum "mark, token."

Didan "to see, regard, catch sight of, contemplate, experience;" Mid.Pers. ditan; O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen."

An → electromotive force produced in a closed electric circuit formed by connecting conductors of different metals in series when the two junctions junctions are maintained at different temperatures. The circuit constitutes a → thermocouple.

Named for the German physicist Thomas Seebeck (1770-1831), who discovered the effect; → effect.

A small single crystal of a semiconductor from which is grown the large single crystal for the manufacture of semiconductor devices.

O.E. sed, sæd; cf. O.N. sað, O.S. sad, O.Fris. sed, M.Du. saet, O.H.G. sat, Ger. Saat; PIE base *se- "to sow."

Toxm "seed" (Tabari tim "seed; race," Laki tôm "seed"), from Mid.Pers. tôhm, tôhmak, tôm, tuxm "seed; extraction; descent;" Av. taoxman- "seed;" O.Pers. taumī:- "family;" cf. Skt. tókman- "offspring, children, race, child," tokma- "young shoot, young blade of corn."

A nucleus from which a variety of → fusion  → chain reactions derive in → stellar nucleosynthesis.

→ seed; → nucleus.

A measure of the blurring and degradation of the image of astronomical objects caused by → turbulence in the Earth's atmosphere, including the telescope environment. Seeing causes the images of stars to break up into → speckle patterns, which change very rapidly with time. See also → Fried parameter; → differential image motion monitor.

→ see; → -ing.

Šekân "wrinkle, plait; curl; rupture, breach," variant of šekan "fold, curl; ripples on water," from šekastan "to break, split;" Mid.Pers. škastan "to break;" Av. scind-, scand "to break, cleave;" Proto-Iranian *skand- "to break, cleave;" PIE sken- "to cut off."

The angular size of a stellar image for long exposures, as determined by the ratio λ/r₀, where λ is the wavelength and r₀ the typical size of → turbulence patches. → Fried parameter. The most common seeing measurement is the → full-width at half-maximumof the seeing disk. → Airy disk.

→ seeing; → disk.

An optical instrument that follows the variation of → atmospheric turbulence by continuously measuring the → seeing conditions.

→ seeing; → monitor.