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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 ...
Noon (or midday) is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m. (for meridiem, literally 12:00 midday), 12 p.m. (for post meridiem, literally "after midday"), 12 pm, or 12:00 (using a 24-hour clock) or 1200 ( military time ). Solar noon is the time when the Sun appears to contact the local celestial meridian.
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 ...
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 ...
Animation showing the difference between a sidereal day and a solar day. Sidereal time ("sidereal" pronounced / saɪˈdɪəriəl, sə -/ sy-DEER-ee-əl, sə-) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky.
A transit of Mercury across the Sun takes place when the planet Mercury passes directly between the Sun and a superior planet. During a transit, Mercury appears as a tiny black dot moving across the Sun as the planet obscures a small portion of the solar disk. Because of orbital alignments, transits viewed from Earth occur in May or November.
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 ...
In astronomy, planetary transits and occultations occur when a planet passes in front of another object, as seen by an observer. The occulted object may be a distant star, but in rare cases it may be another planet, in which case the event is called a mutual planetary occultation or mutual planetary transit, depending on the relative apparent ...