The southern celestial hemisphere, also called the Southern Sky, is the southern half of the

celestial sphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphe ...

; that is, it lies south of the celestial equator. This arbitrary sphere, on which seemingly

fixed stars In astronomy, fixed stars ( la, stellae fixae) is a term to name the full set of glowing points, astronomical objects actually and mainly stars, that appear not to move relative to one another against the darkness of the night sky in the backgro ...

form

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...

s, appears to rotate westward around a polar axis due to

Earth's rotation Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Po ...

. At any given time, the entire Southern Sky is visible from the geographic

South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...

, while less of this hemisphere is visible the further north the observer is located. The northern counterpart is the northern celestial hemisphere.

Astronomy

In the context of astronomical discussions or writing about celestial mapping, it may also simply then be referred to as the Southern Hemisphere. For the purpose of celestial mapping, the sky is considered by astronomers as the inside of a

sphere A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the c ...

divided in two halves by the celestial equator. The Southern Sky or Southern Hemisphere is, therefore, that half of the

that is south of the celestial equator. Even if this one is the ideal projection of the terrestrial equatorial onto the imaginary celestial sphere, the Northern and Southern celestial hemispheres must not be confused with descriptions of the terrestrial hemispheres of

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

itself.

Observation

Acta Eruditorum - V astronomia, 1711 – BEIC 13378880

From the

, in good visibility conditions, the Southern Sky features over 2,000

that are easily visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to norma ...

, while about 20,000 to 40,000 with the aided eye. In large cities, about 300 to 500 stars can be seen depending on the extent of

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

and

air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different type ...

. The farther north, the fewer are visible to the observer. The brightest stars are all larger than the Sun.

Sirius Sirius is the brightest star in the night sky. Its name is derived from the Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CM ...

in the

Canis Major Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast ...

has the brightest

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of −1.46; it has a radius twice that of the Sun and is 8.6

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s away. Canopus and the next fixed star α Centauri, 4.2 light-years away, are also located in the Southern Sky, having declinations around −60°; too close to the south celestial pole for either to be visible from

Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the a ...

History

The Southern Sky was first substantially charted by English astronomer Edmond Halley, and published by him in 1679.

References

Astronomical coordinate systems Hemispheres {{cartography-stub

Astronomy

Observation

History

See also

References