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

Any of several faint, dark, narrow rings around Jupiter. Jupiter's rings are so faint and tenuous that are only visible when viewed from behind Jupiter and are lit by the Sun, or directly viewed in the infrared where they faintly glow. Unlike → Saturn's rings full of large icy and rock chunks, they are composed of tiny rock fragments and dust. Jupiter's rings are continuously losing material and being resupplied with new dust from → meteorite impacts with Jupiter's four inner moons (→ Metis, → Adrastea, → Amalthea, and → Thebe). Jupiter's rings were discovered by NASA's Voyager 1 in 1979. They are composed of three parts: the → Main ring, a → Halo ring that orbits closer to Jupiter, and a very wide → Gossamer ring that extends far from Jupiter.

→ Jupiter; → ring.

→ Jurassic era.

Named for the Jura Mountains on the border between France and Switzerland, where rocks of this age were first studied, + -assic, suffix extracted from Triassic.

A period of the Mesozoic era, spanning the time between the Triassic and the → Cretaceous periods, about 200 to 145 million years ago. The start of the period is marked by the major Triassic-Jurassic → mass extinction event.

→ Jurassic; → era.

1) Of or relating to the administration of justice.
2) Of or relating to law or jurisprudence; legal (Dictionary.com).

From L. iuridicalis "relating to right; pertaining to justice," from iuridicus, from ius "right, law," → jurist, + dicere "to say, to speak."

Dâdšenâxti, of or relating to dâdšenâxt, → jurisprudence

1) The right, power, or authority to administer justice by hearing and determining controversies.
2) The extent or range of judicial, law enforcement, or other authority.
3) The territory over which authority is exercised (Dictionary.com).

M.E., from O.Fr. juridiccion and directly from L. iurisdictionem "administration of justice, jurisdiction," from ius "right, law," → just, + dictio "a saying; extent or range of administrative power."

Dâdbaxšâ, from dâd, → justice, + baxš "division; donor, distributor, divider," from baxšidan "to divide, distribute, grant," → division, + -ân suffix of attribution and nuance

1) The science or philosophy of law.
2) A body or system of laws.
3) Civil Law: Decisions of courts, especially of reviewing tribunals (Dictionary.com).

M.E., from Fr. jurisprudence and directly from L.L. iurisprudentia "the science of law," from iuris "of right, of law" + prudentia "knowledge, a foreseeing, foresight, sagacity."

Dâdšenâxt, literally "science of justice," from dâd, → justice, + šenâxt "knowledge, science," → -logy.

A person versed in the law, as a judge, lawyer, or scholar.

M.E., from M.Fr. juriste, from M.L. iurista "jurist," from L. ius "law," → just.

Dâdšenâs, literally "knower of justice," → jurisprudence.

1) Guided by truth, reason, justice, and fairness.
2) Done or made according to principle; equitable; proper.
3) Based on right; rightful; lawful (Dictionary.com).

M.E. juste, from O.Fr. juste "just, righteous," from L. iustus "upright, equitable," from ius "right," especially "legal right, law," from O.L. ious, perhaps literally "sacred formula."

Dâdmand, from dâd "law, → justice."
Râst, → right.
Dorost "whole, complete, right," → integral.

1) The quality of being just; righteousness, equitableness, or moral rightness.
2) The moral principle determining just conduct.
3) The administering of deserved punishment or reward (Dictionary.com).

M.E., from O.Fr. justice "justice, legal rights, jurisdiction," from L. iustitia "righteousness, equity," from iustus "upright, → just."

Dâd "justice, law" from Mid.Pers. dâd "law, justice, scriptures with legal content;" related to Mid.- and Mod.Pers. daheš "creation," dâdan "to give;" Av. dā- "to place upon, give;" → datum.
Dâdmandi noun from dâmand, → just.
Dâdgari "administration of justice," from dâdgar, literally "just doer," "an administrator of justice," from dâd + -gar, → -or.
Dâdgostari, from Dâdgostar, literally "justice spreader," with gostar, from gostardan "to spread, → expand."

1) A reason, fact, circumstance, or explanation that justifies or defends. What is offered as grounds for believing an assertion.
2) An act of justifying.

Verbal noun of → justify.

Râstâvard, from râst "right, true; just, upright, straight" (Mid.Pers. râst "true, straight, direct;" O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Av. rāz- "to direct, put in line, set," razan- "order;" cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Ger. recht; E. right; PIE base *reg- "move in a straight line," hence, "to direct, rule") + âvard past stem of âvardan "to bring; to adduce, bring forward in argument or as evidence" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").

1) To show (a claim, statement, act, etc.) to be right, reasonable, or proper.
2) To defend or uphold as warranted or well-grounded.
3) To adjust (a line of type) to fill a line of constant width.

Justify, from O.Fr. justifier "to show (something) to be just or right; to administer justice," from L. justificare "act justly toward, make just," from justificus "dealing justly, righteous," from justus "just, upright, equitable," from jus (gen. juris) "right," from O.Latin ious, from PIE base *yewes- (cf. Av. yaož-da- "to purify ritually, to revitalize;" Skt. yos- "(long) life" + root of facere "to do" (from PIE base *dhe- "to put, to do;" cf. Mod.Pers. dâdan "to give;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives; puts;" Skt. dadáti "puts, places;" Hitt. dai- "to place;" Gk. tithenai "to put, set, place;" Lith. deti "to put;" Czech diti, Pol. dziac', Rus. det' "to hide," delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do").

Râstâvard kardan, râstâvardan, infinitives of râstâvard, → justification.

The inner part of the → solar corona which extends to about two solar radii. It is due to the → Thomson scattering of light from the → photosphere by the free electrons in the corona. The K corona exhibits a → linearly polarized continuous spectrum. The high speeds of the scattering electrons (on the average 10,000 km s^-1 for a temperature of 2 million K) smear out the → Fraunhofer lines except the → H and K lines.

K from Ger. Kontinuum, → continuum; → corona.

A → color index correction applied to the photometric magnitudes and colors of a distant galaxy to compensate for the "reddening" of the galaxy due to → cosmological redshift. K correction is intended to derive the magnitudes in the → rest frame of the galaxy. Typically it is given as K(z) = az + bz², where a and b depend on galaxy types. Conversely, one may deduce the redshift of a galaxy by its colors and a K-correction model.

The term K correction, probably stems from the K-term used by C. W. Wirtz (1918, Astron. Nachr. 206, 109), where K stands for Konstante, the German word for constant. The K-term was a constant offset in the redshift applied to diffuse nebulae in that epoch (source: A. L. Kinney, 1996, ApJ 467, 38); → correction.

An orange-red star of → spectral type K with a surface temperature of about 3600-5000 K. The spectra of K stars are dominated by the H and K lines of calcium and lines of neutral iron and titanium, with molecular bands due to cyanogen (CN) and titanium dioxide (TiO). Examples are → Arcturus and → Aldebaran.

K the letter of alphabet; → star.

Same as the → Cretaceous-Tertiary event.

K, representing the "→ Cretaceous period," and T the "→ Tertiary;" → event.

A follow-up mission of the → Kepler satellite funded by → NASA. K2 provides an opportunity to continue Kepler's observations in the field of → exoplanets and expand its role into new astrophysical observations by assigning to Kepler new mission.

K, short for → Kepler spacecraft; 2, for second → mission.

The observed peculiar velocities of galaxies in the → redshift space of → galaxy clusters when the galaxies undergo → infall toward a central mass. This → redshift space distortion differs from the → fingers of God in that the peculiar velocities are not random, but correspond to the coherent falling of galaxies toward the central mass. See also → peculiar velocity.

Kaiser, N., 1987, MNRAS 227, 1; → effect.

The hypothesis of the origin of the solar system proposed first by Kant (1755) and later by Laplace (1796). According to this hypothesis, the solar system began as a nebula of tenuous gas. Particles collided and gradually, under the influence of gravitation, the condensing gas took the form of a disk. Larger bodies formed, moving in circular orbits around the central condensation (the Sun).

Named after the German prominent philosopher Immanuel Kant (1724-1804) and the French great mathematician, physicist, and astronomer Pierre-Simon Marquis de Laplace (1749-1827); → hypothesis.

Any of a group of four short-lived → mesons distinguished by a → quantum number called → strangeness. Also called K meson and denoted K. They are positive, negative, or neutral and have a mass of about 495 MeV/c (about 970 times that of an → electron).

Kaon, from ka (for the letter K) + (mes)on, → meson.

A process based on the effects of → opacity (κ) that drives the → pulsations of many types of variable stars. Consider a layer of material within a star and suppose that it undergoes inward contraction. This inward motion tends to compress the layer and increase the density. Therefore the layer becomes more opaque (See also → partial ionization zone). If a certain amount of flux comes from the deeper layers it gets stuck in the high κ region. The energy accumulates and heat builds up beneath it. The pressure rises below the layer, pushing it outward. The layer expands as it moves outward, cools and becomes more transparent to radiation. Energy can now escape from below the layer, and pressure beneath the layer diminishes. The layer falls inward and the cycle repeats. The κ mechanism is believed to account for the pulsations of several star families, including → Delta Scuti stars, → Beta Cephei variables, → Cepheids, and → RR Lyrae stars (See Baker & Kippenhahn, 1962, Zeitschrift für Astrophysik 54, 114). Same as κ effect and → valve mechanism. See also → gamma mechanism.

κ, the Gk. letter which denotes opacity; → mechanism.