An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The path (up to 320 km wide) that the Moon's shadow traces on the Earth during a total solar eclipse.

→ path; → totality.

1) A person who makes or finds a way, especially through unexplored areas or fields of knowledge.
2) An airplane, or a person dropped from a plane, sent into a target area to illuminate the area for succeeding aircraft (Dictionary.com).
3) → LISA pathfinder.

→ path; → finder.

1) A regular or repetitive form, order, or arrangement; a distinctive form. → diffraction pattern; → interference pattern.
2) In the → density wave model, a region of enhanced stellar density (arm or bar) in the → Galactic disk. → pattern speed.

M.E. patron, from O.Fr. patron, from M.L. patronus "patron saint, lord, master, model, pattern," from pater "father."

Olgu "pattern," from Turkish ülgü "form, mold, model."

In models of → galactic structure, the → angular velocity of a → spiral arm or a → bar, assumed to be a pattern rotating as a solid body in the galaxy. Pattern speed, Ω_P , is one of the most important parameters of the → density wave theory responsible for the spiral arms. Pattern speed determines the location of the → corotation resonance.

→ pattern; → speed.

A quantum mechanical principle according to which no two identical → fermions can share the same → quantum state. Also known as → exclusion principle.

In honor of Wolfgang Pauli (1900-1958), Austrian theoretical physicist, who formulated the principle in 1925; → exclusion; → principle.

The Peacock. A → constellation in the → southern hemisphere, at about 19h 30m → right ascension, 65° south → declination. Abbreviation: Pav; genitive: Pavonis.

From L. pavo "peacock;" paupulo "peacock's sound;" Gk. taos "peacock;"

Tâvus, from Ar., ultimately from Gk. taos "peacock."

The round edible seed of a widely cultivated plant, Pisum sativum, of the legume family.

False singular from M.E. pease (plural pesen), from O.E. pise (West Saxon), piose (Mercian) "pea," from L.L. pisa, variant of L. pisum "pea," from Gk. pison "the pea."

Noxod "pea," from Mid.Pers. naxôd, naxvat "pea."

1) The normal, non warring condition of a nation, group of nations, or the world.
2) (often initial capital letter) An agreement or treaty between warring or antagonistic nations, groups, etc., to end hostilities and abstain from further fighting or antagonism.
3) A state of mutual harmony between people or groups, especially in personal relations.

From M.E. pes, pais, pees, from Anglo-Norman peis, pes, from O.Fr. pais "peace, reconciliation, silence," from L. pacem (nominative pax) "compact, agreement, treaty of peace, tranquility," ultimately from PIE root *pag- "to fasten."

Râman, related to râmeš "tranquility, rest," ârâm "quiet, peaceful," ârâmidan "to become calm, calmed, rest," Mid.Pers. râm "peace," râmenidan "to give peace, pleasure," râmišn "peace, pleasure;" Av. ram- "to stay, rest;" cf. Skt. ram- "to stop, stand still, rest, become appeased;" Gk. erema "quietly, gently;" Goth. rimis "rest;" Lith. rāmas "rest." + suufix -an.

The pointed top of a mountain or ridge. The pointed top of anything. → Gamow peak; → peak wavelength.

Perhaps from M.L.G. pék "pick, pike."

Setiq "summit, top," from *us-tig, from us-, → ex-, + tig "pointed," related to tiq "blade," tiz "sharp," tež, tej, tij; Mid.Pers. tigr, têz, têž "sharp," O.Pers. tigra- "pointed," tigra.xauda- "pointed helmet (epithet of Scythians)," Av. tiγra- "pointed," tiγray- "arrow," tiži.arštay- "with the pointed spear," cf. Skt. tikta- "sharp, pungent, bitter," tejas- "sharpness, edge, point or top of a flame;" PIE base *st(e)ig- "to stick; pointed." Cognates in other IE languages: Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument," L. in-stigare "to goad," O.H.G. stehhan, Ger. stechen "to stab, prick," Du. stecken, O.E. sticca "rod, twig, spoon," E. stick.

The → bolometric luminosity of a → supernova corresponding to the highest brightness in its → light curve. The peak luminosity occurs after the → supernova explosion; it is directly linked to the amount of radioactive ⁵⁶Ni produced in the explosion and can be used to test various explosion models. Following → Arnett's rule, one can derive the ⁵⁶Ni mass from the peak luminosity of a → Type Ia supernova.

→ peak; → luminosity.

The wavelength at which the radiant intensity of a source is maximum.

→ peak; → wavelength.

The pod or the enclosed edible seed of the plant, Arachis hypogaea, of the legume family: the pod is forced underground in growing, where it ripens (Dictionary.com). → box-peanut bulge.

From pea, → green pea galaxy + nut O.E. hnutu, akin to L. nux, → nucleus.

A secretion consisting mainly of calcium carbonate, CaCO₃, produced by various mollusks.

M.E. perle, from O.Fr. perle, M.L. perla of unknown origin.

Morvârid "pearl;" Mid.Pers. murwârid, murgârid; cf. Sogd. marγārit, marrγārt; Khotanese mrāhe. Gk. margarites "pearl" may be a loanword from Iranian.

A partially carbonized vegetable matter, usually mosses, found in bogs and used as fertilizer and fuel.

M.E. pete, of unknown origin.

Turb, from Fr. tourbe, from Germanic turba; cf. O.Fris. turf, O.H.G. zurba, Ger. Torf, O.E. turf, tyrf "slab of soil and grass," E. turf.

Geology: A → sedimentary particle that is between 4 and 64 mm in size. Pebbles are larger than → granules but smaller than → cobbles. Pebbles have typically been rounded by → abrasion during sedimentary transport (geology.com/dictionary).

From M.E. pibel, from O.E. *papol, *pyppel, *pæbbel, of unknown origin.

Rig, from Mid.Pers. rik "pebble, sand."

A planet formation concept that concerns the → accretion of small objects of negligible gravitational mass (ranging from centimeters up to meters in diameter) onto large, gravitating bodies: → planetesimals, → protoplanets, or → planets. In a more narrow sense, pebble accretion is an accretion process where (gas) drag and gravity play major roles. Simply put, this means that the pebble has to be aerodynamically small and the planet to be gravitationally large (C. W. Ormel, in Formation, Evolution, and Dynamics of Young Solar Systems, p. 197, eds. M. Pessah, O. Gressel, Springer, 2017).

→ pebble; → accretion.

In astronomy, designating an object with special properties that deviates from others of its type.
Linguistically related terms: → particular, → special.

From L. peculiaris "of one's own (property)," from peculium "private property," from pecu "flock, farm animals, cattle," pecunia "money, property;" cf. Av. pasu-, fšu- "sheep;" Mid.Pers. pâh, pasvīk "cattle;" Mid./Mod.Pers. šu/ša in šupân/šabân "cattle keeper, shepherd;" Pers. dialects Laki and Tâti pas "sheep;" Skt. paśu- "cattle;" Goth. faihu "money, fortune;" O.E. feoh "cattle, money;" Ger. Vieh "cattle;" Lith. pekus "cattle;" PIE base *peku- "cattle."

Afd "peculiar; strange" (Dehxodâ), from Mid.Pers. afd, awd "peculiar, strange."

An irregular galaxy that has an abnormal shape (neither elliptical, spiral, nor lenticular) and/or has another unusual characteristic.

→ peculiar; → galaxy.

1) The true motion of a star with respect to the Local Standard of Rest. → proper motion.
2) The motion of a cosmological object other than the apparent recession caused by the expansion of the Universe.

→ peculiar; → motion.

A star with a spectrum that cannot be conveniently fitted into any of the standard → spectral classifications.

→ peculiar; → star.