constant of diurnal aberration
pâyâ-ye birâheš ruzâné
Fr.: constante d'aberration diurne
The quantity 0''.3200 ρ cos φ', where ρ is the geocentric distance of the observer measured in units of → equatorial radius the Earth and φ' is the observer's → geocentric latitude. The numerical part is equal to 2πa csc1'' / (cP), where a is the equatorial radius of the Earth, P is its → sidereal period of rotation, and c is the → speed of light in vacuum.
→ constant; → diurnal; → aberration.
Having a period of, occurring in, or related to a → day.
L.L. diurnalis, from V.L. diurnum "day" (Fr. jour), from L. diurnus "daily," from dies "day" + -urnus, an adj. suffix denoting time. Dies "day" from PIE base *dyeu- "to shine;" cf. Gk. delos "clear;" L. deus; Skt. deva "god;" Mod.Pers. div "devil, demon;" O.Pers. daiva- "evil god, demon;" Av. daēva- "evil spirit, false god;" Gk. Zeus "supreme god."
Ruzâné, from ruz→ day + -âné a suffix forming adverbs and adjectives.
Fr.: aberration diurne
The aberration of a star's position due to the rotation of the Earth. Its value depends on the latitude of the observer, and is only 0''.32 in the case of an observer at the equator, where the rotational velocity is greatest.
→ diurnal; → aberration.
parhun-e ruzâné, dâyere-ye ~
Fr.: cercle diurne
The apparent path of an object in the sky during one day, due to Earth's rotation.
Fr.: libration diurne
Daily geometrical libration of the Moon arising from the fact that observers at different points on the Earth see the Moon from slightly different angles. As the Moon rises in the east, you are positioned on one side of our planet, and by the time it sets in the west. Earth's rotation has carried you to the other side. This change in position produces a slight → parallax effect that adds about another 1° of libration in longitude. Two other geometrical libration are → libration in longitude and → libration in latitude. See also → physical libration.
Fr.: mouvement diurne
The daily apparent motion of all celestial objects, due to Earth's rotation.
Fr.: parallaxe diurne
The apparent difference between the position of a celestial object measured from the Earth's surface and the position that would be recorded by a hypothetical observer at the center of the Earth. Same as → geocentric parallax.