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A pole star is a visible star that is approximately aligned with the axis of rotation of an astronomical body; that is, a star whose apparent position is close to one of the celestial poles. On Earth , a pole star would lie directly overhead when viewed from the North or the South Pole .
Sigma Octantis is a solitary [9] star in the Octans constellation that forms the pole star of the Southern Hemisphere.Its name is also written as σ Octantis, abbreviated as Sigma Oct or σ Oct, and it is officially named Polaris Australis (/ p oʊ ˈ l ɛər ɪ s ɔː ˈ s t r eɪ l ɪ s /). [10]
The south celestial pole over the Very Large Telescope [3] Locating the south celestial pole. The south celestial pole is visible only from the Southern Hemisphere. It lies in the dim constellation Octans, the Octant. Sigma Octantis is identified as the south pole star, more than one degree away from the pole, but with a magnitude of 5.5 it is ...
While it may have been used by ancient Egyptians for star maps in some holy books, [1] the earliest text describing the azimuthal equidistant projection is an 11th-century work by al-Biruni. [2] The first use of the projection on a terrestrial map is the pair of hemispheres by Glareanus of about 1510. [1]
The negative pole is the pole toward which the thumb points when the fingers of the left hand are curled in its direction of rotation. This change was needed because the poles of some asteroids and comets precess rapidly enough for their north and south poles to swap within a few decades using the invariable plane definition.
The star Polaris, often called either the "Pole Star" or the "North Star", is treated specially due to its proximity to the north celestial pole. When navigating in the Northern Hemisphere , a simple and quick technique can be used with Polaris to determine the observers latitude or, for larger maritime vessels can be used to calculate any ...
From the South Pole, in good visibility conditions, the Southern Sky features over 2,000 fixed stars that are easily visible to the naked 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 of light and air pollution.
BQ Octantis is a fainter, magnitude 6.82 star located much closer to the South Pole (at less than a degree) than Sigma. In addition to having the current southern pole star of Earth, Octans also contains the southern pole star of the planet Saturn, which is the magnitude 4.3 Delta Octantis.