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

NASA's satellite, designed to measure the diffuse infrared and → cosmic microwave background radiation from the early → Universe. It was launched on November 18, 1989 and carried three instruments: DIRBE (the Diffuse InfraRed Experiment), DMR (Differential Microwave Radiometers), and FIRAS (Far-InfraRed Absolute Spectrophotometer). The COBE observations showed that the cosmic microwave background spectrum matches that of a → blackbody of temperature 2.725 ± 0.002 K. COBE also found anisotropies in the cosmic microwave background at a level of a part in 100,000 (→ cosmic microwave background anisotropy). These tiny variations in the intensity of the CMB over the sky show how matter and energy was distributed when the Universe was still very young. Later, through a process still poorly understood, the early structures developed into galaxies, galaxy clusters, and the large scale structure that we see in the Universe today. Two of COBE's principal investigators, George Smoot and John Mather, received the Nobel Prize in Physics in 2006 for their work on the project.

→ cosmic; → background; → explorer.

A diffuse radiation which consists of the cumulative infrared emission from all galaxies throughout cosmic history. It is about 50 times weaker than the → cosmic microwave background radiation (CMBR). Since the CIB is produced by the dust within such galaxies, it carries a wealth of information about the processes of star formation therein.

→ cosmic; → infrared; → background.

A type of → cosmic defect in the fabric of space-time predicted in some models of the early Universe.

→ cosmic; → texture

The → redshift of a remote object (galaxy, quasar, supenova) due to the expansion of the Universe.

→ cosmological; → redshift.

The repulsive interaction due to the → Coulomb energy between two ions. If the ionic charge is Z, then the Coulomb potential energy is Z²e²/a, where a is some typical separation between the ions. The Coulomb pressure is expected to become important when the ratio Γ_C = Z²e²/akT is much larger than 1. In that case, Coulomb effects dominate those of → thermal agitation and the gas settles down into a → crystal.

→ Coulomb; → pressure.

Logic: An individual case or instance that falsifies a universal generalization. A counterexample to an → argument is a situation in which the → premises are → true, but the → conclusion is → false. For example, "All dogs are mammals" (true). "All cats are mammals" (true). "Therefore, all cats are dogs." (false).

→ counter-; → example.

1) To cause to come into existence.
2) To produce or bring about by a course of action or behavior.

M.E., from L. creatus, p.p. of creare "to make, bring forth, produce," akin to crescere "arise, grow," → crescent.

Âfaridan, âfarin- "to create" (related to nifrin, nefrin "curse"); Mid.Pers. âfrin- "to create, bless;" Av. frī- "to rejoice, please;" cf. Skt. pray- "to please, enjoy, satisfy," O.H.G. friten "to look after;" Ger. frei, → free.

1) The act of producing or causing to exist.
2) The act of being created. See also → creation operator.

Verbal noun of → create.

An operator that acts on the → eigenstate describing the → harmonic oscillator to raise its → energy level by one step. The creation operator is the → Hermitian conjugate operator of the → annihilation operator.

→ creation; → operator.

The religious belief that considers the account of creation given in Genesis to be a scientific description and rejects the Big Bang theory and the theory of evolution. Creationism is a → pseudoscience. Same as "creation science" and "scientific creationism."

→ creation; → -ism.

1a) Commendation or honor given for some action, quality, etc.
1b) A source of pride or honor.
1c) The ascription or acknowledgment of something as due or properly attributable to a person, institution, etc.
1d) Influence or authority resulting from the confidence of others or from one's reputation.
1e) A sum of money due to a person; anything valuable standing on the credit side of an account:
2) To believe; put confidence in; trust; have faith in (Dictionary.com).

M.E., from M.Fr. crédit "belief, trust," from It. credito, from L. creditum "a loan, thing entrusted to another," from p.p. of credere "to trust, entrust, believe."

Arjé, from arj "esteem, honor, dignity; price, worth, value," variant of arz "price, value," arzidan "to be worth;" Mid.Pers. arz- "to be worth;" Av. arj- "to be worth," arəjaiti "it is worth;" Proto-Ir. *Harj- "to be worth;" cf. Skt. arh- "to earn, be worth;" Gk. alphein "to earn, to obtain;" Lith. alga "salary, pay." "to be woth." Arjé dâdan with dâdan "to give, grant, yield," → datum.

An alternative name for Saturn's C ring, which is a wide but faint ring located inside the B Ring. Discovered in 1850 by William and George Bond, it was termed "crepe" because it seemed to be composed of darker material than the brighter A and B Rings.

Crepe, from Fr. crêpe, from O.Fr. crespe, from L. crispa, fem. of crispus "curled;" → ring.

Halqé, → ring; parniyân "a kind of fine painted silk, a mantle of such silk."

Rays of sunlight that appear to diverge from a single point in the sky when parallel columns of light, partially blocked by clouds, pour through gaps in clouds. They result from light scattering and an optical effect called perspective.

Crepuscular "of, pertaining to, or resembling twilight," from L. crepuscul(um), "twilight, dusk," from crepus-, from creper "dusky, dark."

Partowhâ "rays," from partow, → ray; nimtâbi "of, pertaining to, or resembling nimtâb" → twilight.

The figure of the → Moon or an → inferior planet when it is less than half illuminated, as seen by the → observer.

From O.Fr. croissant, from L. crescentum, p.p. of crescere "to grow, increase; spring forth," from PIE base *ker- "to grow" (cf. Gk. kouros "boy," kore "girl," Pers. dialects Laki korr "son, boy," Lori kor "son, boy," Malayeri kora "boy," Kordi kur "son," Arm. serem "bring forth," serim "be born").

Helâl from Ar. Barn "the new moon," from Proto-Iranian *aparnâ- "unfilled," from negation prefix → a- + parnâ- "full;" cf. Mid.Pers. purr mâh "full moon," Av. pərənô-mâh- "full moon," Skt. purna-mâs- "full moon;" → full; → moon.

The first sighting of the → New Moon after its → conjunction with the Sun. Although the date and time of each New Moon can be computed exactly, the visibility of the lunar → crescent as a function of the → Moon's age depends upon many factors and cannot be predicted with certainty. The sighting within one day of New Moon is usually difficult. The crescent at this time is quite thin, has a low surface brightness, and can easily be lost in the → twilight. Generally, the lunar crescent will become visible to suitably-located, experienced observers with good sky conditions about one day after New Moon. However, the time that the crescent actually becomes visible varies from one month to another. The visibility depends on sky conditions and the location, experience, and preparation of the observer. Ignoring atmospheric conditions, the size and brightness of the lunar crescent depend on the → elongation which in turn depends on several factors: 1) The Moon's elongation at New Moon (the elongation of the Moon at New Moon is not necessarily 0). 2) The speed of the Moon in its elliptical orbit. 3) The distance of the Moon, and 4) The observer's location (parallax). The combined effect of the first three factors gives geocentric elongation of the Moon from the Sun at an age of one day which can vary between about 10 and 15 degrees. This large range of possible elongations in the one-day-old Moon is critical (US Naval Observatory).

→ crescent; → moon; → visibility.

The width of the lit area of the → Moon measured along the Moon's diameter.

→ crescent; → width.

The highest point or upper part of a wave.

From O.Fr. creste "tuft, comb," from L. crista "tuft, plume; rooster's comb."

Setiq "summit; anything standing upright," from O.Pers./Av. sta- "to stand, stand still; set," Mod.Pers. istâdan "to stand" (cf. Skt. sthâ- "to stand," Gk. histemi "put, place, weigh," stasis "a standing still," L. stare "to stand") + adj. suffix -iq, variants -ig, -ik, → -ics.

A period of → geologic time which began at the end of the → Jurassic period approximately 145 million years ago and extended to approximately 65 million years ago.

From L. cretaceus, from cret(a) "chalk, clay," + → -aceous, because the geological remains of this period contain heightened chalk deposits.

Gacâsâ, from gac "chalk," Mid.Pers. gac + -âsâ, → -aceous.

The → mass extinction event that destroyed the dinosaurs and a majority of other species on Earth approximately 65 million years ago. This event is believed to have been the impact of a 10 km-size → asteroid or → comet nucleus and its aftereffects, including a severe → impact winter. The collision would have released the energy equivalent to 100 million megatonnes (teratonnes) of → TNT, i.e. more than 10⁹ times the energy of the atomic bomb dropped on Hiroshima on August 6, 1945. Same as the → Cretaceous-Tertiary event.

→ Cretaceous; → Paleogene; → extinction; → event.

See → Cretaceous-Paleogene extinction event.

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