Fr.: transition semi-interdite
Fr.: transition spontanée
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.
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-.
parhun-e gozar, ~ nimruzâni
Fr.: cercle méridien
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.
sâzâl-e gozare nimruzâni
Fr.: instrument méridien
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.
Fr.: méthode du transit
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 of Mercury
Fr.: transit de Mercure
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.
transit of Venus
Fr.: transit de Vénus
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.
durbin-e gozar-e nimruzâni, teleskop-e ~ ~
Fr.: lunette méridienne
Same as → transit instrument.
Fr.: temps de passage
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.
Transiting Exoplanet Survey Satellite (TESS)
mâhvâre-ye bardid-e borun-sayyârehâ-ye gozarandé
A → NASA space telescope devoted to the hunt for planets orbiting the brightest stars in the sky, launched on April 18, 2018. The mission is planned to monitor at least 200,000 stars for signs of → exoplanets using the → planetary transit method. TESS is equipped with four identical refractive → cameras with a combined → field of view (FOV) of 24 × 96 degrees. Each camera consists of a → CCD detector assembly, a → lens assembly, and a lens hood. The → entrance pupil diameter is 10.5 cm and the wavelength range 600 to 1,000 nm. The satellite is a follow-up of NASA's → Kepler spacecraft, but focuses on stars that are 30 to 100 times brighter than those Kepler examined.
Fr.: planète en transit
TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST)
A Belgian facility devoted to the detection and characterization of → exoplanets and to the study of → comets (→ transiting planet) and other → small solar system bodies. It consists of two 60 cm robotic telescopes located at the → European Southern Observatory, → La Silla, in Chile and at Oukaïmden Observatory in Marroco.
1) Passage from one position, state, stage, subject, concept, etc., to another.
From L. transitionem (nominative transition) "a going across or over," noun of action from transire "go or cross over," from → trans- "across" + ire "to go."
gerde-ye gozaresh, disk-e ~
Fr.: disque de transition
The → accretion disk of a → T Tauri star that displays very weak or no → infrared excess at → near infrared wavelengths, but shows strong excess at → intermediate infrared and longer wavelengths. This happens when the hot inner dust disk has dissipated whereas the cooler outer disk is still intact.
Fr.: fonction de transition
Fr.: probabilité de transition
The probability that a quantum-mechanical system will make a transition from a given initial state to a given final state.
Fr.: flux de transition
gozar-e zabarin (#)
Fr.: passage supérieur
The movement of a celestial body across a celestial meridian's upper branch. Same as → upper culmination.
Fr.: transition vibrationnelle