The science that deals with matter and energy and their interactions.
M.E. fisyk(e), phisik(e), from O.Fr. fisique, from L. physica (fem. sing.) "study of nature," from Gk. physike episteme "knowledge of nature," from fem. of physikos "pertaining to nature," from physis "nature," from phyein "to bring forth, produce, make to grow," Gk. phy- "to become;" L. fui "I was," futurus "that is to be, future;" Ger. present first and second person sing. bin, bist; E. to be; O.Ir. bi'u "I am;" Lith. bu'ti "to be;" Rus. byt' "to be."
Loan from Fr. physique, as above.
havâsepehr-e parâsu-taxthâ, javv-e ~
Fr.: atmosphère plan-parallèle
An approximation used in many stellar atmosphere models that depict the atmosphere as being only one-dimensional and bounded at the top and bottom by horizontal plane surfaces normal to the direction of gravity.
fizik-e sayyâregân (#)
Fr.: physique des planètes
The study of the structure, composition, as well as physical and chemical properties of the planets of the solar system, including their atmospheres and their immediate cosmic environment.
A projection or representation of the whole or a part of a sphere on a plane. In particular, a polar projection of the celestial sphere or the Earth on a plane.
Of or relating to → planisphere.
ostorlâb-e taxt-sepehri, ~ kore-yi
Fr.: astrolabe planisphérique
The most common form of the → astrolabe in which both the → celestial sphere and the observer's horizon are projected on to one or more plane surfaces by means of the stereographic projection. See also → universal astrolabe and → particular astrolabe.
fizik-e plâsmâ (#), plâsmâ fizik (#)
Fr.: physique des plasmas
The study of the physical properties of the various forms of plasmas and their processing.
In the magnetosphere, a region of relatively cool (low energy) and dense plasma that may be considered an outer extension of the ionosphere with which it is coupled. Like the ionosphere, the plasmasphere tends to co-rotate with the Earth.
Fr.: sphère de Poincaré
A representation that permits an easy visualisation of all different states of → polarization of a vector wave. The equator represents → linear polarization; the north pole corresponds to right-circular and the south pole to left- → circular polarization.
Named after Henri Poincaré (1854-1912), French mathematician and theoretical physicist, and a philosopher of science; → sphere.
potentially hazardous asteroid (PHA)
seyyârak-e tavandâné âpenâk
Fr.: astéroïde potentiellement dangereux
An asteroid that could make a threatening close approach to the Earth. In technical terms a PHA is defined as having an → absolute magnitude of 22 or brighter and an → Earth Minimum Orbit Intersection Distance (MOID) of less than 0.05 → astronomical unit or 7.5 million km.
Fr.: sphéroïde allongé
An ellipsoid produced by rotating an ellipse through 360° about its major axis. → oblate spheroid.
Fr.: magnétosphère de pulsar
A dense zone of magnetized → plasma surrounding a → pulsar. The magnetosphere, lying between the surface of the → neutron star and the → light cylinder, corotates with the pulsar like a rigid body under the effect of strong magnetic field. The magnetosphere's thickness is determined by the constraint that the corotation velocity of its upper surface should not exceed the → speed of light.
quantum phase transition (QPT)
gozareš-e fâz-e kuântomi
Fr.: transition de phase quantique
A phase transitions that occurs at zero temperature as a function of a non-thermal parameter like → pressure, → magnetic field, or → chemical composition. In contrast to ordinary → phase transitions, which are associated with passage through a critical temperature, quantum phase transitions are associated with → quantum fluctuations, a consequence of → Heisenberg's uncertainty principle. For example, see → Bose-Einstein condensation.
quark-hadron phase transition
gozareš-e fâz-e kuârk-hâdron
Fr.: transition de phase quark-hadron
A phase transition, predicted by cosmological models, to have occurred at approximately 10-5 seconds after the Big Bang to convert a plasma of free quarks and gluons into hadron.
Fr.: phase radiative
The process of producing an image on a sensitive surface by radiation such as X-rays or gamma rays passing through an object.
Rasalhague (α Ophiuchi)
The brightest star (V = 2.08) in the constellation → Ophiuchus. Rasalhague is a → giant star of type A5 lying 47 light-years from Earth. It has a faint, very close companion only 0''.5 away, 7 A.U., that orbits with a period of 8.7 years.
Rasalhague, from Ar. Ra's al-Hayyah (
javv-e bâzhâzandé, havâsepehr-e ~
Fr.: atmosphère réductrice
1) An atmospheric condition in which oxidation is prevented by removal
of oxygen and other oxidating gasses or vapours. Usually nitrogen or
hydrogen gas is used in order to produce specific effects, e.g. on
ceramic wares being fired.
Rho Ophiuchi Cloud
abr-e rho Mâr-afsâ
Fr.: Nuage de rho Ophiuchi
A complex region of molecular and dust clouds containing emission and reflection nebulae near the star ρ Oph in the constellation → Ophiuchus. It is one of the closest star forming regions, some 400 light-years distant. Recent studies using the latest X-ray and infrared observations reveal more than 300 young stellar objects within the large central cloud. Their median age is only 300,000 years.