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

Of, pertaining to, or noting a body having the property of → elasticity. See also → elastic collision, → elastic deformation, → elastic limit, → elastic scattering.

From Fr., from Gk. elastos "ductile, flexible," related to elaunein "to strike, beat out."

Kešâyand, from keš stem of kešidan/kašidan "to pull, drag, draw" (Av. karš- "to draw, to plough," karša- "furrow;" cf. Skt. kars-, kársati "to pull, drag, plough," Gk. pelo, pelomai "to be busy, to bustle") + âyand agent form of âmadan "to come; to become," from Mid.Pers. âmatan (O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes;" O.Iranian *āgmatani; Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").

A collision between two particles which conserves the total kinetic energy and momentum of the system.

→ elastic; → collision.

A deformation of a → solid body in which the change (→ strain) in the relative position of points in the body disappears when the deforming stress is removed. See also → elastic limit.

→ elastic; → deformation.

The smallest → stress beyond which a → solid body can no longer return to its original shape. The material ceases to obey → Hooke's law. Also called → yield point.

→ elastic; → limit.

In a → collision between two → particles, the reaction in which the total → kinetic energy of the system, projectile plus target, is the same before the collision as after.
In the interaction of → electromagnetic waves with particles, the scattering when the → wavelength (→ frequency) of the → scattered light is the same as the → incident light (→ Rayleigh scattering, → Mie scattering).

→ elastic; → scattering.

A wave that propagates by → elastic deformation of the medium. The → propagation takes place by a change in shape that disappears when the forces are removed. In other words, the displaced particles transfer momentum to adjoining particles, and are themselves restored to their original position. A → seismic wave is a type of elastic wave.

→ elastic; → wave.

The ability of a body which has been → deformed by an applied → force to return to its original shape when the force is removed. Up to a certain point the material obeys → Hooke's law. See also → ductility, → plasticity.

→ elastic + → -ity.

In → number theory, the statement that for all → integers, the equation xⁿ + yⁿ = zⁿ has no solution in → positive integer. After 358 years of effort by mathematicians to prove the theorem, a complete proof was found by Andrew Wiles in 1995.

→ Fermat's principle; → last; → theorem.

A process used for covering an object with a thin layer of metal by electrochemical means.

→ galvano- + -plasty a suffix meaning "molding, formation, surgical repair, plastic surgery," from Gk. -plastia, from plastos "molded, formed," from plassein "to mold."

Gâlvânopuši, from gâlvâno-, → galvano-, + puši "covering, coating," from pušidan "to cover; to put on" (Mid.Pers. pôšidan, pôš- "to cover; to wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").

A collision between bodies in which there is a loss of total kinetic energy.

→ inelastic; → collision.

A type of scattering when the → scattered radiation has a → wavelength different from that of the → incident radiation (→ Raman scattering, → fluorescence ).

→ inelastic; → scattering.

Occurring or coming after all others, as in time, order, or place. → last contact, → last quarter

Last, from O.E. latost (adj.) and lætest (adv.), superlative of læt (adj.) and late (adv.); cognate with O.Fris. lest, Du. laatst, O.H.G. laggost, Ger. letzt.

Vâpasin, from vâ-, as intensive prefix, → de-, + pasin, from pas "after, afterward, behind; finally, at last" (Mid.Pers. pas "behind, before, after;" O.Pers. pasā "after;" Av. pasca "behind (of space); then, afterward (of time);" cf. Skt. pazca "behind, after, later;" L. post "behind, in the rear; after, afterward;" O.C.S. po "behind, after;" Lith. pas "at, by;" PIE base *pos-, *posko-) + -in superlative suffix.

To continue in time; go on; endure.

M.E. lasten, from O.E. læstan "to continue, endure;" cf. Goth. laistjan "to follow after," Ger. leisten "to perform, achieve,"), from PIE root *lois- "furrow, track."

Pâyidan "to watch, observe; remain or continue in existence, last," variants pâsidan, pâhidan; Mid.Pers. pây- "to protect, guard;" Sogdian p'y "to observe, protect, watch over;" O.Pers. pā- "to protect," pāta- "protected;" Av. pā- "to protect," pāti "guards," nipā(y)- (with ni-) "to watch, observe, guard," nipātar- "protector, watcher," nipāθri- "protectress;" cf. Skt. pā- "to protect, keep," tanû.pā- "protecting the body," paś.pā- "shepherd;" Gk. poma "lid, cover," poimen "shepherd;" L. pascere "to put out to graze," pastor "shepherd;" Lith. piemuo "shepherd;" PIE base *pā- "to protect, feed."

Same as → fourth contact at an eclipse.

→ last; → contact.

One of the phases of the Moon that appears when it is 90 degrees west of the Sun. Approximately one week after a full moon, when half of the Moon's disk is illuminated by the Sun. → first quarter.

→ last; → quarter.

The epoch in the early evolution of the Universe when matter and photons decoupled. Once atoms formed, light and matter stopped constantly interacting with one another, and photons were able to travel freely. As a result, the Universe became transparent. Light from this period is observed today as the → cosmic microwave background radiation. Same as → decoupling era and → recombination era.

→ last; → scattering.

The set of locations in space corresponding to the → last scattering epoch in the early Universe. It is a spherical surface around the present-day observer from which the → cosmic microwave background radiation appears to emanate.

→ last; → scattering; → surface.

Last in order of birth; youngest.

→ last; → born.

Demâzâ, from Lori, Laki demâzâ, from demâ "last, end, back," related to dom, → tail, + zâ contraction of zâd, → born.

Continuing or remaining for a long time; enduring.

→ last; → -ing.

1a) Capable of being → deformed continuously and permanently without → rupture.
1b) Capable of being molded.
1c) Made or consisting of a plastic.
2) → plastic substance.

From L. plasticus, from Gk. plastikos "that may be molded, pertaining to molding," from plassein "to mold."

Šukâyand, literally "moldable," from šuk, contraction of šuka (Dehxodâ) "a mold in which ingots are cast" + âyand agent noun form of âmadan "to come; to become," → elastic.