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

To convert (energy) from one form into another.

From L. transducere "lead across, transfer," from → trans- "across" + ducere "to lead."

Tarâhâxtan, from tarâ-, → trans-, + hâxtan, hâzidan, from Mid.Pers. "to lead, guide, persuade," Av. hak-, hacaiti "to attach oneself to, to join," cf. Skt. sacate "accompanies, follows," Gk. hepesthai "to follow,", L. sequi "to follow;" PIE *sekw-.

A device that converts one type of energy to another for various purposes, such as a microphone that converts acoustic energy into electrical impulses or a photodetector that converts modulated light waves to electrical currents.

Agent noun of → transduce.

1) The conveying of something or energy from one place or position to another.
→ charge-transfer device; → energy transfer; → heat transfer; → optical transfer function; → radiative transfer; → radiative transfer equation.
2a) To convey or pass from one place to another.
2b) To copy information or images from one place or object to another.

M.E. transferren (v.), from L. transferre "to carry over, transfer, translate," from → trans- "across" + ferre "to carry;" cognate with Pers. bordan "to carry, transport;" Mid.Pers. burdan; O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive);" Skt. bharati "he carries;" Gk. pherein "to carry;" PIE base *bher- "to carry."

Tarâvaž, from tarâ-, → trans- "across," + važ, variant vâz (in parvâz), Av. vaz- "to draw, guide; bring; possess; fly; float," vazaiti "guides, leads" (cf. Skt. vah- "to carry, drive, convey," vahati "carries," pravaha- "bearing along, carrying," pravāha- "running water, stream, river;" L. vehere "to carry;" O.E. wegan "to carry;" O.N. vegr; O.H.G. weg "way," wegan "to move," wagan "cart;" M.Du. wagen "wagon;" PIE base *wegh- "to drive;" see also → flight).

The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.

→ transfer; → function.

1) Math.: A mathematical quantity obtained from a given quantity by an algebraic, geometric, or functional transformation.
The transformation itself.
2) To change in form, appearance, or structure; to change in condition, nature, or character; convert.
Physics: To change into another form of energy.
To increase or decrease (the voltage and current characteristics of an alternating-current circuit), as by means of a transformer.
Math.: To change the form of (a figure, expression, etc.) without in general changing the value.

→ trans- + → form.

1) The act or process of transforming. The state of being transformed.
2) The relationship between description of a physical phenomenon in one → reference frame to another. → Galilean transformation; → Lorentz transformation.
3) Math.: The act, process, or result of transforming or mapping.

Verbal noun of → transform.

A device that converts low voltages to higher voltages, or vice versa. A transformer consists of a primary coil and a secondary coil, both traversed by the same magnetic flux.

→ transform + → -or.

General: Lasting for only a short time; not permanent.
Physics: A non-periodic signal of short duration. A sudden pulse of voltage or current.

From L. transiens "passing over or away," pr.p. of L. transire "to go or cross over," from → trans- "cross" + ire "to go."

Gozarâ "transient," from gozar present stem of gozaštan "to pass, cross, transit," variant gozâštan "to put, to place, let, allow;" Mid.Pers. widardan, widâštan "to pass, to let pass (by);" O.Pers. vitar- "to pass across," viyatarayam "I put across;" Av. vi-tar- "to pass across," from vi- "apart, away from" (O.Pers. viy- "apart, away;" Av. vi- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + O.Pers./Av. tar- "to cross over;" → trans-.

A short-lived change in the brightness of patches on the face of the Moon. The TLPs last from a few seconds to a few hours and can grow from less than a few to a hundred kilometers in size. They have been reported by many observers since the invention of the telescope. However, the physical mechanism responsible for creating a TLP is not well understood. Several theories have been proposed, among which lunar outgassing, that is, gas being released from the surface of the Moon.

→ transient; → lunar; → phenomenon.

A general term for all events of astronomical nature occurring in the sky and lasting only for a relatively short duration, such as → supernova explosions, → gamma-ray bursts, → flare stars, → luminous red novae, eclipsing brown dwarfs, → tidal disruption events, etc.

→ transient; → sky.

An X-ray source that appears suddenly in the sky, strongly increases its intensity over a few days, and then declines with a lifetime of several months.

→ transient; → X-ray source.

An active semiconductor device with a small low-powered solid-state electronic device consisting of a semiconductor and three or more electrodes, used as an amplifier and rectifier and frequently incorporated into integrated circuit chips. Although much smaller in size than a vacuum tube, it performs similar functions without requiring current to heat a cathode.

From trans-, from → transfer + -istor, from → resistor; → resistance.

1) An event where one astronomical object appears to move across the face of another. As seen from Earth, the planets Venus and Mercury are seen to transit the Sun. We can also observe natural satellites transit the face of their host planet. Similarly exoplanets have been observed to transit their host stars. See also → planetary transit, → transit method.
2) The passage of a heavenly body across the meridian of a given location.

M.E., from L. transitus, p.p. of transire "to go or cross over," from → trans- "across" + ire "to go."

Gozar "passage, transit, passing," from gozaštan "to pass, cross, transit," variant gozâštan "to put, to place, let, allow;" Mid.Pers. widardan, widâštan "to pass, to let pass (by);" O.Pers. vitar- "to pass across," viyatarayam "I put across;" Av. vi-tar- "to pass across," from vi- "apart, away from" (O.Pers. viy- "apart, away;" Av. vi- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + O.Pers./Av. tar- "to cross over;" → trans-.

An observing instrument provided with a graduated vertical scale, used to measure the declinations of heavenly bodies and to determine the time of meridian transits. Same as → meridian circle.

→ transit; → circle; nimruzâni, adj. of nimruzân, → meridian.

An instrument mounted so as to allow it to be pointed only at objects in the sky crossing the local meridian. Also known as → transit telescope.

→ transit; → instrument.

A method for detecting → exoplanets that is based on the decrease of star → brightness when the exoplanet passes in front of its star. As the planet transits, a portion of the light from the star is blocked causing a decrease in the → magnitude of the star. The amount of decrease (typically between 0.01% and 1%) depends on the sizes of the star and the planet. The duration of the transit depends on the planet's distance from the star and the star's mass. This change must be periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time. Once detected, the planet's distance from its star can be calculated from the period and the mass of the star using → Kepler's third law of planetary motion. The size of the planet is found from the depth of the transit and the size of the star. From the orbital size and the temperature of the star, the planet's characteristic temperature can be calculated. Knowing the star's mass and size, the planet's size and distance can be estimated. Also the composition of a → transiting planet's atmosphere can, in principle, be determined.

→ transit; → method.

The crossing the face of the Sun by the planet Mercury, as seen from Earth. Because the plane of Mercury's orbit is not exactly coincident with the plane of Earth's orbit, Mercury usually appears to pass over or under the Sun. On the average it occurs 13 times each century when the Earth is near the → line of nodes of Mercury's orbit. The three last transits were on 2003 May 07, 2006 November 08, and 2016 May 09. The next one will be on 2019 November 11. The first observation of a transit of Mercury was on November 7, 1631 by Pierre Gassendi. On June 4, 2014 NASA's Mars rover Curiosity photographed a transit of Mercury, marking the first time such a phenomenon has ever been imaged from the surface of a planet other than Earth. See also → black drop.

→ Mercury; → transit.

A rare phenomenon that happens when the planet Venus passes directly between the Sun and Earth and is therefore seen against the solar disk. Such a passage occurs every 122 or 105 years and when it happens the next occurrence is after 8 years. Only seven transits of Venus have occurred since the invention of the telescope: in 1639, 1761, 1769, 1874, 1882, 2004, and 2012. The next one will be in 2117. The reason for this rarity is that the Earth and Venus do not orbit the Sun in the same plane. Their orbital planes have a relative inclination of about 3°. The first observation of the Venus transit was in 1639 by the English Jeremiah Horrocks (1618-1641). See also → black drop.

→ Venus; → transit

Same as → transit instrument.

→ transit; → telescope.

The time interval between the release of an electron at the photocathode and the arrival of an electron at the anode. Transit time is not a single-valued quantity, but has a bell-shaped distribution.

→ transit; → time.