In astronomy, circumpolar constellations are constellations that never fall below the horizon when viewed from the poles [1] or at a given latitude of the Earth . All other constellations due to the rotation of the Earth and the axial tilt relative to the Sun are called seasonal or setting constellations.
Stars and constellations that are circumpolar depend on the latitude of the observer. In the northern hemisphere, some stars and constellations will always be visible in the northern circumpolar sky [2] . The same applies to the southern hemisphere , where certain stars and constellations will always be visible in the southern circumpolar sky. The North Pole , currently marked by the Polar Star , from which it is separated at a distance of less than 1 °, always has an azimuth of 0. The pole height for a given latitude φ is fixed, and its value is determined by the following formula: A = 90 ° -φ . Similarly, in the southern hemisphere, all objects with a declination less than A = -90 ° + φ are non-coincident. All stars with a declination greater than A are circumpolar [3] . They never disappear below the horizon, as their circulation occurs above the horizon and they are visible throughout the night. Because of this quality, they used to be used for navigation.
Viewed from the North Pole , all fully visible constellations to the north of the celestial equator are circumpolar, as well as constellations visible to the south of the celestial equator , as viewed from the South Pole . At the equator, circumpolar constellations are not visible. As can be seen from the definition at middle northern latitudes (north of 40 - 50 ° N ), the circumpolar constellations include:
- Great Bear ;
- Ursa Minor ;
- Dragon ;
- Cepheus ;
- Cassiopeia ;
- Giraffe [4] .
Accordingly, at middle southern latitudes (south of 40 - 50 ° S ), circumpolar constellations include:
- Octant ;
- The Paradise Bird ;
- Peacock ;
- Indian ;
- Toucan ;
- South Hydra ;
- Dining Mountain .
See also
- Undying star
Notes
- (Eng.) Shivers, Jay S. (2011), Programming Recreational Services , Jones & Bartlett Publishers , p. 319, ISBN 1449656250 , < https://books.google.com/books?id=Fy2GBiDEU2oC&pg=PA319 >
- (Eng.) Ridpath, Ian (2006), Eyewitness Companions: Astronomy , Penguin , p. 148, ISBN 0756648459 , < https://books.google.com/books?id=OEZ7n1YKMlMC&pg=PA148 >
- ↑ (Eng.) Karttunen, Hannu; Kröger, Pekka & Oja, Heikki et al., Eds. ( 2007 ), Fundamental Astronomy (5th ed.), Springer Science & Business Media , p. 19, ISBN 3540341447 , < https://books.google.com/books?id=DjeVdb0sLEAC&pg=PA19 >
- , (Eng.) Young, Charles Augustus ( 1897 ), With the Small Telescope , Ginn, p. 9−14 , < https://books.google.com/books?id=tylLAAAAIAAJ&pg=PA9 >