why do the stars appear to rotate around polaris
Whether a star is circumpolar depends upon the observer's. Since the of the north or (whichever is visible) equals the of the observer's latitude,
any star whose from the visible is less than the absolute latitude will be circumpolar. For example, if the observer's latitude is 50` N, any star will be circumpolar if it is less than 50` from the north celestial pole. If the observer's latitude is 35` S, then all stars within 35` of the south celestial pole are circumpolar. Stars on the are not circumpolar when observed from any latitude in either hemisphere of the Earth. "A star with its polar distance approximately equal to or less than the latitude of the observer". Whether a given star is circumpolar at the observer's latitude (h) may be calculated in terms of the star's (d). The star is circumpolar if h + d is greater than +90` (observer in ), or h + d is less than 90` (observer in ). "A star whose diurnal circle lies above the horizon never sets, even though it cannot be seen during the day.
Designation of a star as circumpolar depends on the observer's latitude. At the equator no star is circumpolar. At the North or South Pole all stars are circumpolar, since only one half of the celestial sphere can ever be seen. For an observer at any other latitude a star whose declination is greater than 90` minus the observer's latitude will be circumpolar, appearing to circle the celestial pole and remaining always above the horizon. A constellation made up entirely of circumpolar stars is also called circumpolar. From most of the United States (above lat. 40`N) the Big Dipper is circumpolar". Similarly, the star will never rise above the local horizon if d h is less than 90` (observer in Northern Hemisphere), or d h is greater than +90` (observer in Southern Hemisphere). Thus, is invisible from such locations as and, if marginally visible from, and. Some stars within the far northern (such as, and ) roughly north of the (+23m`) will be circumpolar stars, which never rise or set.
For British observers, for example, the first magnitude stars (declination +45` 59') and (+45` 16') do not set from anywhere in the country. (+38` 47') is technically circumpolar north of latitude +51` 13' (just south of ); taking into account, it will probably only be seen to set at sea level from and the. Some stars within the far southern constellations (such as, and ) roughly south of the (-23m`) will also be circumpolar stars. Stars (and constellations) that are circumpolar in one hemisphere are always invisible in the high latitudes of the opposite hemisphere, and these never rise above the horizon. For example, the southern circumpolar star is invisible from most of the, likewise, the seven stars of the northern circumpolar are invisible from most of the region of. What seems as aparent motion is really called Relative motion. The constaelations observed on the Northern sky of the Globe do moves but because of the.
What seems as aparent motion is really called Relative motion. The constaelations observed on the Northern sky of the Globe do moves but because of the great Universal distances from our perspective appear as standing still. Ursa majoris (the Big dipper) constains a star called Polaris. The name stems from the Zenith observation that it practically line up with Polarisand for that reason its called the North Star because it line up with the North pole of the Earth. Now the Earth spin on the axis of the poles. The stars appear fixed but the earth is moving but on earth due to the principle of relativity we dont see ourselves moving. On the basis of this relative motion we are actually able to tell what time it is on earth. Therefore we see the stars moving in relative motion. The stars in the Big Dipper then appear to rotate relative to the Earth but polaris appears fixed. The reason is the relative motion of the Poles to Poraris is neglible.
- Views: 42
why do we only see stars at night
why do stars seem to move in the night sky
why do some stars shine brighter than others
why do we see stars in the sky
why do stars appear to move from east to west
why do stars appear to move across the night sky
why does the rotational axis of earth precess