Wikipedia

Southern celestial hemisphere

Thesouthern celestial hemisphere,also called theSouthern Sky,is thesouthern halfof thecelestial sphere;that is, it liessouthof thecelestial equator.This arbitrary sphere, on which seeminglyfixed starsformconstellations,appears to rotatewestward around apolar axisas the Earthrotates.

Astar chartof the entire Southern Sky, centered on the southcelestial pole

At all times, the entire Southern Sky is visible from the geographicSouth Pole;less of the Southern Sky is visible thefurther norththe observer is located. The northern counterpart is thenorthern celestial hemisphere.

Astronomy

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Earth rotatingwithin thecelestial sphere.In this view, the southern celestial hemisphere is below thecelestial equator,the middle parallel (in cyan).

In the context ofastronomicaldiscussions or writing aboutcelestial mapping,it may also simply then be referred to as the Southern Hemisphere.

For the purpose of celestial mapping, the sky is considered byastronomersas the inside of aspheredivided in two halves by thecelestial equator.[according to whom?]The Southern Sky or Southern Hemisphere is, therefore, that half of thecelestial spherethat is south of the celestial equator. Even if this one is the idealprojectionof the terrestrial equatorial onto the imaginary celestial sphere, the Northern and Southern celestial hemispheres should not be confused with descriptions of theterrestrialhemispheresofEarthitself.[according to whom?]

Observation

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Chart of the southern constellations from declination –40° to the south celestial pole by the Jesuit missionaryFrançois Noëlpublished inActa Eruditorum,1711.

From theSouth Pole,in good visibility conditions, the Southern Sky features over 2,000fixed starsthat are easily visible to thenaked eye,while about 20,000 to 40,000 with the aided eye.[citation needed][dubious–discuss]In large cities, about 300 to 500 stars can be seen depending on the extent oflightandair pollution.[citation needed]The farther north, the fewer are visible to the observer.[citation needed]

The brightest star in the night sky is located in the southern celestial hemisphere and is larger than theSun.Siriusin theconstellationof Canis Major has the brightestapparent magnitudeof −1.46; it has a radius twicethat of the Sunand is 8.6light-yearsaway.Canopusand the next fixed starα Centauri,4.2 light-years away, are also located in the Southern Sky, having declinations around −60°; too close to thesouth celestial polefor either to be visible fromCentral Europe.[1]

Of the88 modern constellations,45 are only visible from the Southern celestial hemisphere with 15 other constellations along the equator and have portions on the northern hemisphere. The southern constellations are:[citation needed][2]

History

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The first telescopicchartof the Southern Sky was made by the English astronomerEdmond Halley,[3][4]from the island ofSt Helenain theSouth Atlantic Oceanand published by him in 1678.[5]

See also

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References

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  1. ^David Ellyard, Wil Tirion:The Southern Sky Guide.Cambridge Univ. Press, Cambridge 2009,ISBN978-0-521-71405-1
  2. ^"International Astronomical Union | IAU".www.iau.org.Retrieved2024-02-13.
  3. ^"Edmond Halley (1656–1742)".BBC.2014.Retrieved2021-07-11.
  4. ^"Edmond Halley's southern star catalogue".Retrieved2023-07-26.
  5. ^Kanas, Nick (2012).Star Maps: History, Artistry, and Cartography(2nd ed.). Chichester, UK: Springer. p. 123.ISBN978-1-4614-0917-5.
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