An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13 Search : event
compound event
  رویداد ِ چندساخت   
ruydâd-e candsâxt

Fr.: événement composé   

In statistics, an event whose probability of occurrence depends upon the probability of occurrence of two or more independent events.

compound; → event.

cosmic-ray event
  رویداد ِ پرتوهای ِ کیهانی   
ruydâd-e partowhâ-ye keyhâni

Fr.: événement des rayons cosmiques, un cosmique   

Spurious signals in CCD frames caused by ionizing radiation which appear as a set of pixels with intense values sparsely scattered over the CCD frame. High energy particles generate muons, which deposit around 80 electrons per micron in silicon. With a collection depth of 10-20 microns, a cosmic-ray event is seen on a CCD frame as having a signal of up to a few thousand electrons, usually concentrated in one or two pixels. Although attributed to cosmic-ray hits, they may also be due to background terrestrial radiation.

cosmic rays; → event.

Cretaceous-Paleogene extinction event
  رویداد ِ خاموشی ِ گچاسا-پارینزاد   
ruydâd-e xâmuši-ye Gacâsâ-Pârinzâd

Fr.: extinction Crétacé-Tertiaire   

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. Same as the → Cretaceous-Tertiary event.

Cretaceous; → Paleogene; → extinction; → event.

Cretaceous-Tertiary event
  رویداد ِ K-T   
ruydâd-e K-T (#)

Fr.: événement K-T   

See → Cretaceous-Paleogene extinction event.

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

event
  رویداد   
ruydâd (#)

Fr.: événement   

1) General: Something that happens or is regarded as happening; an occurrence, especially one of some importance.
2) Einstein's relativity: An occurrence in the → space-time continuum referenced by three spatial coordinates and a complementary temporal ordinate. → world line; → space-time diagram.
3) Statistics: A subset of the → sample space.

From M.Fr. event, from L. eventus "occurrence, issue," from evenire "to come out, happen, result," from → ex- "out" + venire "to come," from PIE base *gwem- "to go, come;" cf. Mod/Mid.Pers. gâm "step, pace;" O.Pers. gam- "to come; to go;" Av. gam- "to come; to go," jamaiti "goes;" Mod.Pers. âmadan "to come;" 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.

Ruydâd, noun from ruy dâdan "to occur, happen," originally "to appear," from ruy "face; aspect; appearance" (Mid.Pers. rôy, rôdh "face;" Av. raoδa- "growth," in plural "appearance," from raod- "to grow, sprout, shoot;" cf. Skt. róha- "rising, height") + dâdan "to give; to command" (Mid.Pers. dâdan "to give;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" cf. Skt. dadáti "he gives;" Gk. didomi "I give;" L. dare "to give, offer," facere to make;" PIE base *do- to give").

event horizon
  افق ِ رویداد   
ofoq-e ruydâd (#)

Fr.: horizon d'événement   

1) The surface surrounding a → black hole with the property that any light ray emitted inside it cannot escape to the outer space because of the strength of the → gravitational field. The radius of the event horizon is called the → Schwarzschild radius. See also → photon sphere.
2) For an observer A at the instant t0, the surface in the → space-time that divides the collection of all events into two non-empty classes: those events that have been, are being, or will be observed by A, and those that A has never observed and will never be able to observe (J. Plebanski, A. Krasinski, 2006, An Introduction to General Relativity and Cosmology, Cambridge Univ. Press).

event; → horizon.

impact event
  رویداد ِ برخورد   
ruydâd-e barxord

Fr.: impact cosmique   

A collision between two celestial objects, specially solar system bodies, with considerable consequences. Impact events involve release of large amounts of energy. Some examples are the 1908 Siberian → Tunguska event by a → comet, the → Barringer Crater, and the collision of an → asteroid with Earth 65 million years ago, which is thought to have led to the extinction of the dinosaurs and other species of the → Cretaceous-Paleogene period.

impact; → event.

independent events
  رویدادهای ِ ناوابسته   
ruydâdhâ-ye nâvâbasté (#)

Fr.: événements indépendants   

Statistics: Two events if the occurrence of one of them gives no → information about whether or not the other event will occur; these events have no influence on each other.

independent; → event.

K-T event
  رویداد ِ K-T   
ruydâd-e K-T (#)

Fr.: événement K-T   

Same as the → Cretaceous-Tertiary event.

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

microlensing event
  رویداد ِ ریزلنزش   
ruydâd-e rizlenzeš

Fr.: événement de microlentille   

The effect arising whenever a source star and lens star pass each other at an angular separation involving the → Einstein radius (RE) of the lens. The time-scale for such an event is defined as tE = RE/v, where v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane.

microlensing; → event.

polarity event
  رویداد ِ قطبیگی   
ruydâd-e qotbigi

Fr.: événement de polarité   

A specific event in the history of Earth's magnetic field. Usually used in reference to a specific → polarity reversal.

polarity; → event.

simple event
  رویداد ِ ساده   
ruydâd-e sâdé

Fr.: événement simple   

Statistics: An event consisting of a single point of the → sample space.

simple; → event.

Tunguska event
  رویداد ِ تونگوسکا   
ruydâd-e Tunguska (#)

Fr.: événement de la Toungouska   

The violent impact of a comet or meteorite in the Tunguska region of Siberia on 30 June 1908. The object exploded in the atmosphere before touching the ground at an estimated height of 5-10 km. Observers reported seeing a fireball as bright as the Sun. The explosion caused a shock wave that shook buildings and caused damage, though there was no loss of human life. The first expedition to the remote area of the explosion took place in 1927. An estimated 80 million trees covering more than 2,150 square km were flattened. The energy of the explosion is estimated to have been equivalent to that of about 15 → megatons of TNT , a thousand times more powerful than the atomic bomb dropped on Hiroshima in 1945.

From the name of the central Siberian region, Russ. Podkamennaya (Lower Stony) Tunguska River, today Krasnoyarsk Krai; → event.