An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < ani foc iso Pla pla pla rog > >>

Number of Results: 133 Search : plan
sayyârak (#)

Fr.: planétoïde   

An older equivalent for → asteroid.

planet + → -oid.

sayyârešenâsi (#)

Fr.: planétologie   

Same as → planetary science.

planet; + → -logy.

taxt- (#)

Fr.: plani-   

Variant of → plano-, as in → planisphere.


  تخت-سپهر، تخت-کره   
taxt-sepehr, taxt-koré

Fr.: planisphère   

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.

plani-; → sphere.

  تخت-سپهری، تخت-کره‌ای   
taxt-sepehri, taxt-kore-yi

Fr.: planisphérique   

Of or relating to → planisphere.

planisphere + → -ic..

planispheric astrolabe
  اسطرلاب ِ تخت-سپهری، ~ کره‌ای   
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.

planispheric; → astrolabe.

planned obsolescence
  پیتاری ِ پیشگاشته   
pitâri-ye pišgâšté

Fr.: obsolescence programmée   

The business strategy of deliberately designing products so they have a limited effective lifespan. Its objective is to incite the consumer to abandon the currently owned item and buy another one.

Planned, p.p. of "to → plan;" → obsolescence.

taxt- (#)

Fr.: plano-   

A combining form meaning "flat, plane," used in the formation of compound terms. Also plani- and plan- before a vowel, → plane.


plano-concave lens
  عدسی ِ تخت-کاو   
adasi-ye taxt-kâv (#)

Fr.: lentille plano-concave   

A → divergent lens composed of one concave surface and one plane surface. This type of lens has a negative focal point and produces a → virtual image.

plano-; → concave; → lens.

plano-convex lens
  عدسی ِ تخت-کوژ   
adasi-ye taxt-kuž (#)

Fr.: lentille plano-convexe   

A → convergent lens that has one flat side and one convex side. Plano-convex lenses focus parallel rays of light to a positive point, thus forming → real images.

plano-; → convex; → lens.

giyâh (#)

Fr.: plante   

A living organism, in the Kingdom Plantae, with cellulose cell walls and lacking a nervous system or powers of voluntary motion.

M.E. plaunte; O.E. plante; L. planta "shoot, sprig, scion."

Giyâh "plant;" dialectal Bašâkardi gidâ(h), gida; Av. gaodāyu-, literally "cattle nourisher," from gao- "cattle, bull, ox," → Taurus, + dāyu- "nourisher," from dā(y)- "to feed" (Gershevitch 1962); Mod.Pers. dâyé "wet nurse;" cognate with L. femina "woman, female," → feminism; PIE base *dheh(i)- "to suck, suckle."

post-planetary nebula star
  ستاره‌ی ِ پسا-میغ ِ سیاره‌ای   
setâre-ye pasâ-miq-e sayyâre-yi

Fr.: étoile post-nébuleuse planétaire   

An evolved star whose → planetary nebula has dissipated.

post-; → planetary; → nebula; → star.

preplanetary nebula (PPN)
  پیش-میغ ِ سیاره‌ای   
piš-miq-e sayyâre-yi

Fr.: pré-nebuleuse planétaire   

A short-lived transition object between the → asymptotic giant branch (AGB) and → planetary nebula phases. See also → post-asymptotic giant branch star (post-AGB).

pre-; → planetary; → nebula. The more commonly used term, → protoplanetary nebula, is a misnomer and must be avoided. Indeed → protoplanetary is widely used to refer to disks around → pre-main sequence stars. Since the term → protoplanet is used to denote planets undergoing formation, the use of the term "protoplanetary nebula" to mean a completely different kind of object is an unfortunate choice (Sahai et al. 2005, ApJ 620, 948).


Fr.: protoplanète   

A stage in the formation of a → planet, which comes about from the aggregation of → planetesimals. The protoplanet eventually becomes a planet by → accretion of material from a → protoplanetary disk.

proto- + → planet.


Fr.: protoplanétaire   

Of or relating to a → protoplanet or protoplanets.

protoplanet; → -ary.

protoplanetary disk
  گرده‌ی ِ پوروا-سیاره‌ای   
gerde-ye purvâ-sayyâreyi

Fr.: disque protoplanétaire   

A → circumstellar disk of gas and dust surrounding a → pre-main sequence star from which planetary systems form. Protoplanetary disks are remnants of → accretion disks which bring forth stars. Typically, their sizes are ~100-500 AU, masses ~10-2 solar masses, lifetimes ~106-107 years, and accretion rates ~10-7-10-8 solar masses per year. According to the standard theory of planet formation, called core accretion, planets come into being by the growth of → dust grains which stick together and produce ever larger bodies, known as → planetesimals. The agglomeration of these planetesimals of 100 to 1000 km in size into rocky Earth-mass planets is the main outcome of this theory. Beyond the → snow line in the disk, if the masses of these cores of rock and ice grow higher than 10 times that of Earth in less than a few million years, gas can rapidly accrete and give rise to giant gaseous planets similar to → Jupiter. If core building goes on too slowly, the disk gas dissipates before the formation of → giant planets can start. Finally the left-over planetesimals that could not agglomerate into rocky planets or core of giant planets remain as a → debris disk around the central object that has become a → main sequence star. An alternative to core accretion theory is formation of planets in a massive protoplanetary disk by → gravitational instabilities. The validity of these two theories is presently debated. See also → protoplanet.

protoplanet; → disk.

protoplanetary nebula
  پیش-میغ ِ سیاره‌ای   
piš-miq-e sayyâre-yi

Fr.: pré-nebuleuse planétaire   

preplanetary nebula.

proto-; → planetary; → nebula.

pulsar planet
  سیاره‌ی ِ پولساری، تپار ِ ~   
sayyâre-ye pulsâri, tapaar-e ~

Fr.: planète de pulsar   

A planet orbiting a → pulsar. The first such planet to be discovered was around a → millisecond pulsar known as PSR 1257+12.

pulsar; → planet.

reduced Planck constant
  پایای ِ پلانک ِ باز‌هازیده   
pâyâ-ye Planck-e bâzhâzidé

Fr.: constante de Planck réduite   

The → Planck constant divided by 2π and denoted ħ, pronounced h-bar. Also called the → Dirac constant.

Reduced, p.p. of → reduce; → Planck's constant.

reduced Planck's constant
  پایای ِ پلانک ِ باز‌هازیده   
pâyâ-ye Planck-e bâzhâzidé

Fr.: constante de Planck réduite   

reduced Planck constant.

reduced Planck constant.

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