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.
Fr.: magnitude apparente
A measure of a star's observed brightness (opposed to → absolute magnitude); symbol m. It depends on the star's → intrinsic brightness, its distance from the observer, and the amount of → interstellar absorption. The brightest star → Sirius has an apparent magnitude of -1.46, while the weakest stars visible with the naked eye in the most favorable observation conditions have magnitudes of about +6.5. The stars of magnitudes less than +23 are measured by professional observatories, whereas those of magnitudes less than +30 by a telescope such as the → Hubble Space Telescope (M.S.: SDE).
Fr.: midi vrai
The moment when the center of the Sun crosses the meridian. Same as true noon.
Fr.: position apparente
Same as → apparent position.
naheš-e padidâr, jâ-ye ~
Fr.: position apparente
1) The position on the celestial sphere at which a heavenly body
would be seen from the Earth at a particular time.
Fr.: lever apparent
Fr.: coucher apparent
apparent sidereal day
ruz-e axtari-ye padidâr
Fr.: jour sidéral apparent
apparent sidereal time
zamân-e axtari-ye padidâr
Fr.: temps sidéral apparent
The → mean sidereal time corrected for the → nutation and shift in the obliquity of the ecliptic that occurs as a result of the Moon's gravitational effect. Apparent sidereal time differs from mean sidereal time in that the → true vernal equinox point is used.
apparent solar day
ruz-e xoršidi-ye padidâr
Fr.: jour solaire vrai
The duration of one rotation of the Earth on its axis (→ Earth's rotation), with respect to the → apparent Sun. It is measured by successive transits of the apparent Sun over the lower branch of a → meridian.
apparent solar time
zamân-e xoršidi-ye padidâr
Fr.: temps solaire apparent
The time based on the motion of the → apparent Sun and kept by dividing the day into 24 equal hours.
Fr.: Soleil apparent
The → true Sun as seen by an observer on Earth. The term "apparent Sun" is used in contrast to → mean Sun, which refers to an average of the Sun's position). See also: → apparent solar time and → mean solar time.
apparent visual magnitude
borz-e didegâni-ye padidâr
Fr.: magnitude visuelle apparente