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Astronomical transit. Phobos transits the Sun, as viewed by the Perseverance rover on 2 April 2022. In astronomy, a transit (or astronomical transit) is the passage of a celestial body directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of the larger ...
A sundial was read and corrected with the table or graph of the equation of time. If a transit instrument was available, the sun's transit across the meridian (the moment the sun appears to be due south or north of the observer) was noted; the clock was then set to noon and offset by the number of minutes given by the equation of time for that ...
A common observation made at a transit [20] is recording the times when the disk of Mercury appears to be in contact with the limb of the Sun. [21] Those contacts are traditionally referred to as the 1st, 2nd, 3rd and 4th contacts – with the 2nd and 3rd contacts occurring when the disk of Mercury is fully on the disk of the sun. [22]
The astronomical system of units is a tridimensional system, in that it defines units of length, mass and time. The associated astronomical constants also fix the different frames of reference that are needed to report observations. [ 2] The system is a conventional system, in that neither the unit of length nor the unit of mass are true ...
Transit-timing variation is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small as that of Earth. In tightly packed planetary systems, the gravitational pull of the planets among ...
The planets that have been studied by both methods are by far the best-characterized of all known exoplanets. [ 16] The transit method also makes it possible to study the atmosphere of the transiting planet. When the planet transits the star, light from the star passes through the upper atmosphere of the planet.
Culmination. In observational astronomy, culmination is the passage of a celestial object (such as the Sun, the Moon, a planet, a star, constellation or a deep-sky object) across the observer's local meridian. [ 1] These events are also known as meridian transits, used in timekeeping and navigation, and measured precisely using a transit ...
Longitude by chronometer is a method, in navigation, of determining longitude using a marine chronometer, which was developed by John Harrison during the first half of the eighteenth century. It is an astronomical method of calculating the longitude at which a position line, drawn from a sight by sextant of any celestial body, crosses the ...