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.
Fr.: astéroïde Apollon
A member of a class of → near-Earth asteroids (NEAs) that have orbital → semi-major axes greater than that of the Earth (> 1 → astronomical unit) but → perihelion distances less than the Earth's → aphelion distance (less than 1.017 AU); thus, they cross the Earth's orbit when near the perihelia of their orbits. They are named for the prototype Apollo.
The point in a lunar orbit that is farthest from the center of the Lune. Also → apocynthion.
From → apo- "away from, off" + lune "moon," from L. luna; PIE *louksnâ- "moon," literally "luminous, bright;" compare with O.Pers. raucah-, Av. raocah- "light, luminous; daylight," Skt. roka "brightness, light," cognate with Gk. leukos "white, clear," L. lux "light" (also lumen, luna), PIE *leuk- "light, brightness". The Mod.Pers. words rowšan, raxšân "bright, clear," ruz "day," foruq "light," and afruxtan "to light, kindle" also belong to this family, as well as the E. light, Ger. Licht, and Fr. lumière.
Apâmah, apâmâh, → apocynthion.
Fr.: appareil, dispositif
An appliance or device for a particular purpose: an X-ray apparatus. An integrated group of materials or devices used for a particular purpose.
From L. apparatus "equipment, preparation," from p.p. of apparare "to prepare," from ad- "to" + parare "make ready".
Dastgâh "any manufacturing instrument, a loom; ustensils".
General: Open to view, visible; appearing as actual to
the eye or mind.
O.Fr. aparant, from L. apparentem, pr.p. of apparere "to appear," from ad- "to" + perere "to come forth, be visible".
Padidâr "appearing, manifest," from padid "evident, clear, in sight," from Mid.Pers. patdit, from O.Pers./Av. patiy-/paiti "toward, against, back" (cp. Skt. prati- "near, toward, against, in return," Gk. proti, pros "face to face with, toward, in addition to") + O.Pers./Av. di-/dâ(y)- "to see" (Skt. dhi- "to think"), Mod.Pers. didan "to see".
tarâmun-e padidâr, qotr-e ~
Fr.: diamètre apparent
The angular diameter of a celestial body expressed in degrees, minutes, and seconds of arc, or in radians.
Fr.: distance apparente
The angular distance between two celestial bodies (e.g. the components of a binary star system), expressed in degrees, minutes and seconds of arc.
Fr.: champ apparent
The angular diameter of the circle of light that the eye sees through an eyepiece.
Fr.: horizon apparent
The circle determined by the intersection of the heavens with a → cone whose → vertex is the → eye, and whose elements are tangent to lines of the Earth's surface. Same as → visible horizon. Assuming that there is no → atmospheric refraction, apparent horizon coincides with → geometric horizon. See also → sea horizon.