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

The → rotation of the Moon's → orbit within the → orbital plane, whereby the axes of the ellipse change direction. The Moon's → major axis makes one complete revolution every 8.85 Earth years, or 3,232.6054 days, as it rotates slowly in the same direction as the Moon itself (direct, or → prograde motion). The Moon's apsidal precession is a → relativistic effect, and should not be confused with its → axial procession.

→ Moon; → apsidal; → precession.

A system of → spectral classification introduced in 1943 by William W. Morgan (1906-1994), Philip C. Keenan (1908-2000), and Edith M. Kellman (1911-2007) at Yerkes Observatory. Also known as the MK (or MKK) classification or the → Yerkes system.

Named after the two main astronomers, as above; → classification.

A classification scheme of galaxies based on their apparent shape. → Hubble classification.

→ morphological; → classification.

An observationally determined relationship between the → morphological classification of galaxies and the → environments in which they are located. Specifically, the morphology-density relation indicates that early-type galaxies (→ ETG) are preferentially located in high density environments, whereas late-type galaxies (→ LTG) are preferentially found in low density environments. Hence, spiral galaxies are rare in the high densities of clusters and are common in the lower density group environments. Early-type galaxies, on the other hand, are common in clusters and are rarely found in isolation.

→ morphology; → density; → relation.

The action or process of moving or of changing place or position; movement.

Verbal noun of → move.

In general, the process of repeatedly adding a quantity to itself a certain number of times, or any other process which has the same result.

Verbal noun of → multiply.

The sign used to indicate multiplication, either a times sign (×), a centered dot (·), or an asterisk. The multiplication sign was introduced by William Oughtred in 1631.

→ multiplication; → sign.

Same as → Charpak's detector.

→ multi-; → wire; → proportional; → chamber.

A sudden, random change in the genetic material of a cell. → commute.

From L. mutationem (nominative mutatio) "a changing," from mutatus, p.p. of mutare "to change," from PIE base *mei- "to change, go, move;" cf. Av. miθô "inverted, false," miθaoxta- "wrong spoken;" Skt. methati "changes, alternates, joins, meets," mith- "to alternate, meet," mithás "opposite, in opposition;" L. meare "to go, pass," mutuus "done in exchange;" Goth. maidjan "to change;" E. prefix mis- (in mistake).

Muteš, verbal noun of mutidan, from L. mutare, cognate with Av. miθô, as above, + -idan infinitive suffix.

The act of mystifying or the condition of being mystified.

→ mystify; → -tion.

The outer region of a → quasar or an → active galactic nucleus displaying narrow spectral lines. Also called Type II AGN. See also → obscuring torus.

→ narrow; → line; → region.

A large body of people united by common descent, history, culture, or language, inhabiting a particular state. → national, → international.

Nation, from O.Fr. nacion, from L. nationem (nom. natio) "nation, stock, race," literally "that which has been born," from natus, p.p. of nasci "to be born;" cognate with Pers. zâdan, → generate.

Nafân, from Av. nāfaēna- "family," hama.nāfaēna- "of the same family," related to nāfa- "near relationship, family, navel," napāt- "grandson" (Mod.Pers. navé "grandson"); cf. Mid.Pers. nâf "family," nâfag "navel," naft "descendant, " Parthian nap "family" (Mod.Pers. nâf "navel"); Sogd. nâf "country;" Sorani Kurd. natawa (Kurmanji Kurd. netewe) "family, race, nation," from *nafata (with metathesis); cf. Skt. nábhi- "nave, navel, central part; home, origin;" Gk. anepsios "cousin, sister's son;" L. nepos "grandchild; descendant;" O.Lithuanian neputis "grandson; nephew;" O.H.G. nabalo "navel;" Ger. Nabel "navel;" O.E. nefa "grandson; descendant;" + -ân suffix denoting family relationship, as in Bâbakân "family of Bâbak."

Of, involving, or relating to a nation as a whole. → National Aeronautics and Space Administration (NASA).

→ nation; → -al.

A federal agency of the United States government founded in 1958 for civil aeronautical research and space exploration, superseding the National Advisory Committee for Aeronautics (NACA). Its goals include improving human understanding of the universe, the solar system, and Earth and establishing a permanent human presence in space. NASA is headquarted at Washington, D.C., and operates several research, development, and test facilities, as follows alphabetically: 1) Ames Research Center; 2) Dryden Flight Research Facility at Edwards, California, used for flight testing and as a landing site for the Space Shuttle; 3) Glenn Research Center at Cleveland, Ohio, concerned with aircraft and rocket propulsion; 4) Goddard Space Flight Center; 5) Jet Propulsion Laboratory; 6) Johnson Space center; 7) Kennedy Space Center; 8) Langley Research Center at Hampton, Virginia, which carries out research in aeronautics and space technology; 9) Marshall Space Flight Center; 10) the Space Telescope Science Institute; 11) Stennis Space Center, near Bay St Louis, Mississippi, for testing rocket engines; and 12) Wallops Flight Facility on Wallops Island, Virginia, which manages NASA's sounding rocket and scientific balloon programs.

→ national; → aeronautics; → space; administration, verbal noun of administer, from M.E. amynistre, from O.Fr. aministrer, from L. administrare "to serve, carry out, manage," from → ad- "to" + ministrare "to serve," from minister "servant, priest's assistant," from minus, minor "less," hence "subordinate," + comparative suffix *-teros.

Sâzmân, → organization; fazâyi pertaining to fazâ, → space; Âmrikâ "United State of America."

Loyalty and devotion to a nation; especially: a sense of national consciousness exalting one nation above all others and placing primary emphasis on promotion of its culture and interests as opposed to those of other nations or supranational groups (Merriam-Webster.com).

→ national; → -ism.

1) National status; specifically: a legal relationship involving allegiance on the part of an individual and usually protection on the part of the state b : membership in a particular nation.
2) Membership in a particular nation (Merriam-Webster.com).

→ national; → -ity.

The transfer of a major branch of industry or commerce from private to state ownership or control (OxfordDictionaries.com)

→ nationalize; → -tion.

1) To bring under the ownership or control of a nation, as industries and land (Dictionary.com).

→ national; → -ize.

One of a set of → differential equations that describes the motion of a → fluid as a function of → pressure, → density, total external force, and → viscosity. See also → Euler equation.

Named after Claude-Louis Navier (1785-1836), a French engineer and physicist, and George Gabriel Stokes, → stokes; → equation.

Same as → nautical astronomy.

Navigational, adj. of navigation, from L. navigationem (nom. navigatio), from navigatus, p.p. of navigare "to sail, steer a ship," from navis "ship," cognate with Pers. nâv "ship," as below, + root of agere "to drive," → act; → astronomy.

Axtaršenâsi→ astronomy; nâvrâni "navigation," from nâv "ship;" O.Pers./Av. *nāv-, O.Pers. nāviyā- "fleet;" cf. Skt. nau-, nava- "ship, boat" + râni verbal noun of rândan "to drive, to cause to go," causative of raftan "to go, walk, proceed" (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").