Diurnal motion - wikipedia Diurnal motion This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( December 2009 ) Diurnal motion ( Latin : diurnus, lit. ' daily ', from dies, lit. `` day '' ) is an astronomical term referring to the apparent daily motion of stars around Earth, or more precisely around the two celestial poles. It is caused by the Earth 's rotation around its axis, so almost every star appears to move along a circular arc path 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 conducted by Léon Foucault. Relative direction The relative direction of diurnal motion in the Northern Celestial Hemisphere are as follows : Facing north, below Polaris : rightward, or eastward Facing north, above Polaris : leftward, or westward Facing south : rightward, or westward Thus, northern circumpolar stars move counter clockwise around Polaris, the north pole star. At the North Pole, the cardinal directions do not apply to diurnal motion. Within the circumpolar circle, all the stars move simply rightward, or looking directly overhead, counterclockwise around the zenith, where Polaris is. Southern Celestial Hemisphere observers are to replace north with south, left with right, and Polaris with Sigma Octantis, sometimes called the south pole star. The circumpolar stars move clockwise around Sigma Octantis. East and west are not interchanged. As seen from the Equator, the two celestial poles are on the horizon due north and south, and the motion is counterclockwise ( i.e. leftward ) around Polaris and clockwise ( i.e. rightward ) around Sigma Octantis. All motion is westward, except for the two fixed points. Apparent speed The daily arc 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 equals this cosine times 15 ° per hour, 15 arcminutes per minute, or 15 arcseconds per second. Per a certain period of time, a given angular distance traveled by an object along or near the celestial equator may be compared to the angular diameter of one of the following objects : up to one Sun or Moon diameter ( about 0.5 ° or 30 ' ) every 2 minutes up to one diameter of the planet Venus in inferior conjunction ( about 1 ' or 60 `` ) about every 4 seconds 2,000 diameters of the largest stars per second Star trail and time - lapse photography capture diurnal motion blur. The apparent motion of stars near the celestial pole seems slower than that of stars closer to the celestial equator. Conversely, following the diurnal motion with the camera to eliminate its arcing effect on a long exposure, can best be done with an equatorial mount, which requires adjusting the right ascension only ; a telescope may have a sidereal motor drive to do that automatically. References Retrieved from `` https://en.wikipedia.org/w/index.php?title=Diurnal_motion&oldid=789371937 '' Categories : Astrometry Stellar astronomy Hidden categories : Articles lacking sources from December 2009 All articles lacking sources Articles containing Latin - language text Talk About Wikipedia Català Español Français 한국어 日本 語 Norsk Norsk nynorsk 中文 Edit links This page was last edited on 6 July 2017, at 23 : 41. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what is the daily motion of the earth
Answer: an astronomical term referring to the apparent daily motion of stars around Earth, or more precisely around the two celestial poles