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

A symbol of → predicate logic which expresses that the statements within its scope are → true for at least one instance of something. The symbol ∃ is used as the existential quantifier. Existential quantifiers are normally used in logic in → conjunction with → predicate symbols, which say something about a → variable or → constant, in this case the variable being quantified (→ quantify, → quantification).

→ existential; → quantifier.

A philosophical attitude associated especially with Heidegger, Jaspers, Marcel, and  Sartre, and opposed to → rationalism and  → empiricism, that stresses the individual's  unique position as a self-determining agent responsible for the authenticity of his or  her choices (Dictionary.com).

→ existential; → -ism.

An advocate of → existentialism.

→ existential; → -ist.

A way or passage out.

From L. exit "he or she goes out," from exire "to go out," from → ex- "out" + ire "to go;" cf. Gk ion " going," neut. pr.p. of ienai "to go;" Pers. ây-, â- present stem of âmadan "to come;" O.Pers. aitiy "goes;" Av. ay- "to go, to come," aēiti "goes;" Skt. e- "to come near," eti "arrival;" Goth. iddja "went," Lith. eiti "to go;" Russ. idti "to go."

Osraft, from os-, → ex- "out," + raft, raftan "to go, walk," → entrance.

In an → optical system, the → image of the → aperture stop formed by the elements following it. See also → entrance pupil.

→ exit; → pupil.

Prefix meaning "outside; outer; external" used in the formation of compound words: exoplanet, exosphere, exocentric.

From Gk. exo "outside," used in forming scientific terms, → ex-.

Borun-, from borun "out, the outside" (Mid.Pers. bêron, from bê "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river").

The altitude at which the atmosphere becomes collisionless.

→ exo-; → base.

The study of life beyond the Earth's atmosphere, as on other planets; also → astrobiology.

→ exo-; → biology.

An → exoplanet similar to Earth.

→ exo- + → earth.

→ extraterrestrial life.

→ exo-; → life.

A → European Space Agency (ESA) program to investigate the Martian environment and to demonstrate new technologies paving the way for a future Mars sample return mission in the 2020's. Two missions are foreseen: one consisting of an Orbiter plus an Entry, Descent and Landing Demonstrator Module (EDM), launched in 2016, and the other, featuring a rover, with a launch date of 2018. Both missions will be carried out in cooperation with Russia's Roscosmos space agency. The ExoMars program will demonstrate a number of essential flight and in-situ enabling technologies that are necessary for future exploration missions, such as an international Mars Sample Return mission. At the same time, a number of important scientific investigations will be carried out. The 2016 mission included a Trace Gas Orbiter (TGO) and an EDM. The Orbiter will carry scientific instruments to detect and study atmospheric trace gases, such as methane. The EDM will contain sensors to evaluate the lander's performance as it descends, and additional sensors to study the environment at the landing site. The 2018 mission includes a rover that will carry a drill and a suite of instruments dedicated to exobiology and geochemistry research.

ExoMars, short for "→ exobiology on → Mars."

A natural → satellite orbiting an → extrasolar planet.

→ exo-; → moon.

Same as → extrasolar planet.

→ exo- + → planet.

Of, relating to, or resembling an → exoplanet or exoplanets.

→ exoplanet; → -ary.

A → planetary system consisting of → exoplanets orbiting a star other than Sun.

→ exoplanetary; → system.

The passage of an → exoplanet across the face its star.

→ exoplanetary; → transit.

The part of → astrophysics that searches and studies → extrasolar planets.

→ exoplanet; → -logy.

1) The outermost portion of the Earth's → atmosphere. Extremely tenuous, it lies above the → ionosphere from a height of about 500 km, to the edge of → interplanetary space.
2) An extremely tenuous kind of atmosphere surrounding a → solar system body. Since the → mean free path is much greater than the atmospheric scale height. The → atoms or → molecules never collide with each other. → lunar exosphere.

→ exo- + → sphere.

Relating to or describing any process in which a system releases heat to its surrounding environment.

From → exo- + -therm, from Gk. therme "heat," from PIE *ghwerm-/*ghworm- "warm;" cf. Pers. garm "warm;" L. fornax "an oven;" O.E. wearm "warm" + → -ic.

From garmâ "heat, warmth" (Mid.Pers. garm; O.Pers./Av. garəma- "hot, warm;" cf. Skt. gharmah "heat;" Gk. thermos "warm;" L. formus "warm;" P.Gmc. *warmaz; O.E. wearm; O.H.G., Ger. warm; PIE *ghworm-/*ghwerm-, as above) + zâ verbal adj. and agent noun of zâdan "to bring foth, give birth," (Mid.Pers. zâtan; Av. zan- "to bear, give birth to a child, be born," infinitive zazâite, zâta- "born;" cf. Skt. janati "begets, bears;" L. gignere "to beget;" PIE base *gen- "to give birth, beget").

1) Of foreign origin or character; not native; introduced from abroad, but not fully naturalized or acclimatized.
2) Strikingly unusual or strange in effect or appearance.
3) Of a uniquely new or experimental nature (Dictionary.com).
See: → exotic star.

M.E., from M.Fr. exotique and directly from L. exoticus, from Gk. exotikos "foreign," literally "from the outside," from → exo- "outside."

Osgânik, from os-, → ex-, + gân relation suffix, from Mid.Pers. -gânag, -gâna, + -ik, → -ic.