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- Diurnal_motion abstract "Diurnal motion is an astronomical term referring to the apparent daily motion of stars around the Earth, or more precisely around the two celestial poles. It is caused by the Earth's rotation on its axis, so every star apparently moves on a circle, that is called the diurnal circle. The time for one complete rotation is 23 hours, 56 minutes and 4.09 seconds (1 sidereal day). The first experimental demonstration of this motion was undertaken by Léon Foucault.Direction of the motion in the Northern hemisphere: Looking to the north, below the North Star: left-right, west-east Looking to the north, above the North Star: right-left, east-west Looking to the south: left-right, east-westThus northern circumpolar stars move counterclockwise around the North Star.At the North Pole, north, east and west are not applicable, the motion is simply left-right, or looking vertically upward, counterclockwise around the zenith.For the southern hemisphere, interchange north/south and left/right, and replace North Star by southern celestial pole. The circumpolar stars move clockwise around it. East/west are not interchanged.At the equator the two celestial poles are at the horizon and motion is counterclockwise (i.e. to the left) around the North Star and clockwise (i.e. to the right) around the southern celestial pole. All motion is from east to west, except for the two stationary points.The daily path of an object on the celestial sphere, including the possible part below the horizon, has a length proportional to the cosine of the declination. Thus the speed of the diurnal motion of a celestial object is this cosine times 15 °/hr = 15'/min = 15"/s, i.e. (compare angular diameter): Up to a Sun or Moon diameter every two minutes ca. four seconds for the largest planet 2000 diameters of the largest stars per secondDiurnal motion can be seen in stop motion photography. Circumpolar stars close to the celestial pole move only slowly. Conversely, following the diurnal motion with the camera, to eliminate it on the photograph, can best be done with an equatorial mount, which requires adjusting the right ascension only; a telescope may have a motor to do that automatically (sidereal drive).".
- Diurnal_motion wikiPageID "142348".
- Diurnal_motion wikiPageRevisionID "540530489".
- Diurnal_motion hasPhotoCollection Diurnal_motion.
- Diurnal_motion subject Category:Astrometry.
- Diurnal_motion subject Category:Stellar_astronomy.
- Diurnal_motion comment "Diurnal motion is an astronomical term referring to the apparent daily motion of stars around the Earth, or more precisely around the two celestial poles. It is caused by the Earth's rotation on its axis, so every star apparently moves on a circle, that is called the diurnal circle. The time for one complete rotation is 23 hours, 56 minutes and 4.09 seconds (1 sidereal day).".
- Diurnal_motion label "Diurnal motion".
- Diurnal_motion label "Mouvement diurne".
- Diurnal_motion label "Movimiento diurno".
- Diurnal_motion label "周日運動".
- Diurnal_motion label "日周運動".
- Diurnal_motion sameAs Movimiento_diurno.
- Diurnal_motion sameAs Mouvement_diurne.
- Diurnal_motion sameAs 日周運動.
- Diurnal_motion sameAs 일주_운동.
- Diurnal_motion sameAs m.011y3s.
- Diurnal_motion sameAs Q1195520.
- Diurnal_motion sameAs Q1195520.
- Diurnal_motion wasDerivedFrom Diurnal_motion?oldid=540530489.
- Diurnal_motion isPrimaryTopicOf Diurnal_motion.