Fr.: système aplanétique
→ aplanatism; → system.
Freedom from spherical aberration and coma.
Aplanatism, from aplanatic, from a- "negation prefix" + Gk. plane "wandering," from planasthai "to wander" + -tic adjective-forming suffix.
Nâbirahi, from nâ- "negation prefix" + birah "a devious path; a wanderer, who deviates, errs," + -i noun affix.
Prefix meaning "away from, off; out of; without," ap- before a vowel or h.
From Gk. apo "away from, from;" cf. Av. apâ "away from, from."
Persian apâ- from Av. and O.Pers. apâ "away from, from". Compare with Skt. apa "away, off," L. ab- "from, away," Hittite appa, Gothic af-, Ger. ab-, E. of, off; PIE *apo- "off, away."
The point in an orbit where the moving body lies furthest from the celestial body around which it turns.
The point on an elliptic orbit at the greatest distance from the principal focus or center of attraction.
Same as → apochromatic lens.
Fr.: lentille apochromatique
A lens that is → apochromatic.
Fr.: système apochromatique
An optical system that is → apochromatic.
The capacity of an optical system to bring three widely separated wavelengths of light into a single focus.
apâfâmidan, apâfâm kardan
To bring the wavelengths of the spatially separate colors to a common focus.
The point in a lunar orbit that is farthest from the center of the Lune. Also apolune.
Apocynthion, from → apo- "away from, off" + cynthion, from Gk. Cynthia "goddess of the Moon."
1) Generally, any process suppressing the secondary maxima of a
diffraction pattern, such as the faint rings around the Airy disk
of an optical image. This allows the telescope to resolve finer details.
Apodization from v. apodize, → a- "negation prefix" + pod from Gk. podos "foot" (compare with Pers. pâ, see below) + -tion "noun forming suffix;" literally "removing feet," i.e. suppressing the secondary maxima at the side of the Airy spot.
Pâzodâyi "removing feet," from pâ "foot," Mid.Pers. pâd, pây , Av. pad-, Skt. pat, Gk. pos, gen. podos, L. pes, gen. pedis, PIE *pod-/*ped-. Zodâyi, n. from zodudan "to polish, clean," Mid.Pers. uzdâtan, Av. uzdâ-, from uz-, → ex-, + dâ- "make, create."
The point on an elliptic orbit at the greatest distance from the principal focus. Also knwon as → apocenter.
Of or pertaining to an → apogalacticon.
The point at which a celestial body is farthest from the center of a galaxy; opposite of → perigalacticon.
The point in the orbit of the moon or an artificial satellite that is farthest from the terrestrial center and at which the body's velocity is at a minimum.
From Fr. apogée, from L. apogæum, from Gk. apogaion "away from the earth," from → apo- "off, away" + gaia/ge "earth." According to Dehxodâ, the term owj used in Persian is neither Ar. nor Skt. (contrary to the opinions of Khwarazi and Biruni respectively), but the corrupt form of the above Gk. term.
Apâzam, from apâ-, → apo-, + Av. zam- "the earth," Mid.Pers. zamig, Mod.Pers. zami, zamin "the earth;" cf. Skt. ksam, Gk. khthôn, khamai "on the ground," L. homo "earthly being" and humus "the earth" (as in homo sapiens or homicide, humble, humus, exhume); PIE root *dh(e)ghom "earth".
Fr.: éclipse apogée
An eclipse (of the Sun or Moon) which takes place when the Moon is at the → apogee of its orbit. The solar apogee eclipses, when they are not partial, are always → annular. The maximum duration of an apogee solar eclipse is 6h 15m (between the → first contact and the → fourth contact). The maximum duration of a lunar apogee eclipse, between the two exterior contacts of the Moon with the → penumbra, is 6h 18m (the maximum totality being 1h 44m) (M.S.: SDE).
apogee full Moon
pormâng-e apâzam, pormâh-e ~
Fr.: pleine lune d'apogée
The → full Moon when our natural satellite is at its farthest position from the Earth. The difference in apparent size with respect to the → perigee full Moon represents a difference in distance of just under 50,000 km between → apogee and → perigee, given the Moon's average distance of about 385,000 km. Also called → full micro Moon.