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Information about Pole Star

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Long exposure of stars appearing to circle the North Celestial pole. The daily rotation of Earth creates the appearance of rings around the pole.
For other uses, see Polestar (disambiguation).


A pole star is a visible star that is approximately aligned with the Earth's axis of rotation; that is, a star that lies in the direction pointed to by one of Earth's poles. There are potentially both north and south pole stars, but whether there is either depends on the current stellar configuration. The term the pole star usually refers to the star Polaris (colloquially referred to as the "north star") which is the current northern pole star.

Pole stars change over time because stars exhibit a slow but distinct drift with respect to the Earth's axis. The primary reason for this is the precession of the Earth's rotational axis that causes its orientation to change over time. If the stars were fixed in space, precession would cause the position of a pole star to trace out an imaginary circle on the celestial sphere approximately once every 26,000 years. However, the stars themselves exhibit motion relative to each other (including the sun), and this so-called proper motion is another cause of the apparent drift of a pole star.

Pole stars are often used in celestial navigation. While other stars' positions change throughout the night, the pole stars' position in the sky does not. Therefore, they are a dependable indicator of the direction toward its respective pole.

North pole

Further information: North Star
At the present time, Polaris is the pole star in the northern direction. Its mean position (taking account of precession and proper motion) will reach a maximum declination of +89°32'23", so 1657" or 0.4603° from the celestial north pole, in February 2102. (Its current declination is +89°15'50.8".) Its maximum apparent declination (taking account of nutation and aberration) will be +89°32'50.62", so 1629" or 0.4526° from the celestial north pole, on 24 March 2100. (ref: Jean Meeus, Mathematical Astronomy Morsels Ch.50; Willmann-Bell 1997)

South pole

Further information: South Star
Sigma Octantis is the closest star to the south celestial pole, but it is too faint to serve as a useful pole star. The Southern Cross constellation functions as an approximate southern pole constellation, by pointing to where a southern pole star would be. At the equator it is possible to see both Polaris and the Southern Cross.

Other planets

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Pole star or polar star may also refer to:
  • Philip Segal, an Executive Producer with his own company, Polestar
  • Zbigniew Cybulski, a Polish actor
  • Polestar (comics), a Spider-Man villain
  • PoleStar, a scenario analysis tool

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EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001. Their greatest hit, their debut single "time after time", peaked at #13 in the Oricon singles chart.
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This article is about rotation as a movement of a physical body. For other uses, see Rotation (disambiguation).
A rotation is a movement of an object in a circular motion.
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North is one of the four cardinal directions, specifically the direction that, in Western culture, is treated as the primary direction: north is used (explicitly or implicitly) to define all other directions; the (visual) top edges of maps usually correspond to the
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South is most commonly a noun, adjective, or adverb indicating direction or geography.

South is one of the four cardinal directions or compass points. It is the opposite of North and at right angles to East and West.
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Polaris (α UMi / α Ursae Minoris / Alpha Ursae Minoris), more commonly known as The North Star or simply North Star, is the brightest star in the constellation Ursa Minor.
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The precession of Earth's axis of rotation with respect to inertial space is also called the precession of the equinoxes. Like a wobbling top, the direction of the Earth's axis is changing; while today, the North Pole points roughly to Polaris, over time it will change.
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celestial sphere is an imaginary rotating sphere of "gigantic radius", concentric and coaxial with the Earth. All objects in the sky can be thought of as lying upon the sphere.
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The proper motion of a star is the measurement of its change in position in the sky over time after improper motions are accounted for. This contrasts with radial velocity which is the measurement of the change in distance toward or away from the viewer over time.
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For the episode of The West Wing, see .
Celestial navigation, also known as astronavigation, is a position fixing technique that was devised to help sailors cross the featureless oceans without having to rely on dead reckoning to enable them to
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North Star is a title of the star best suited for navigation northwards. A candidate for navigation northward must be viewable from Earth and circumpolar to the north celestial pole. The current one is Polaris.
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Polaris (α UMi / α Ursae Minoris / Alpha Ursae Minoris), more commonly known as The North Star or simply North Star, is the brightest star in the constellation Ursa Minor.
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Precession refers to a change in the direction of the axis of a rotating object. In physics, there are two types of precession, torque-free and torque-induced, the latter being discussed here in more detail.
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The proper motion of a star is the measurement of its change in position in the sky over time after improper motions are accounted for. This contrasts with radial velocity which is the measurement of the change in distance toward or away from the viewer over time.
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In astronomy, declination (abbrev. dec or δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle.
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This article or section contains information about scheduled or expected future events.
It may contain tentative information; the content may change as the event approaches and more information becomes available.
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Nutation is a slight irregular motion (etymologically a "nodding") in the axis of rotation of a largely axially symmetric object, such as a gyroscope or a planet.

The nutation of a planet is due to the fact that the tidal forces which cause the precession of the equinoxes
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Aberration has several meanings:
  • An abnormality of chromosomes
  • A disorder in one's mental state (see Mental illness)
In optics:
  • Optical aberration, an imperfection in image formation by an optical system

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March 24 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

March 24
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The South Star is the star which is circumpolar to the celestial south pole (as Polaris, the North Star, is for the celestial north pole), and can thus be reliably used for navigation. The present Naked eye South Star is Sigma Octantis with 5.
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Sigma Octantis (σ Oct / σ Octantis) is a magnitude 5.5 star in the constellation Octans.

Its position near the southern celestial pole makes it the southern hemisphere's pole star and counterpart to Polaris, the current North Star.
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CRUX is a lightweight, i686-optimized Linux distribution targeted at experienced Linux users. The distribution is delivered by a tar.gz-based package system with BSD-style initscripts. CRUX also has a ports system to install and upgrade applications.
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equator is an imaginary line on the Earth's surface equidistant from the North Pole and South Pole. It thus divides the Earth into a Northern Hemisphere and a Southern Hemisphere. The equators of other planets and astronomical bodies are defined analogously.
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Alpha Pictoris (α Pic / α Pictoris) is a star in the constellation Pictor. It has an apparent magnitude of 3.30. Alpha Pictoris has the distinction of being the south pole star of Mercury.

References

  1. SIMBAD Query Result

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Mercury  

Mariner 10 photomosaic of Mercury
Orbital characteristics[1]
Epoch J2000
Aphelion distance: 69,816,927 km
0.46669733 AU
Perihelion distance: 46,001,210 km
0.
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δ Doradus is a faint star in the Dorado constellation that has the distinction of being the Moon's south pole star. It is better aligned than Earth's Polaris (α Ursae Minoris), but much fainter.
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Moon  

The Moon as seen by an observer on Earth
Orbital characteristics
Periapsis: 363,104 km
0.0024 AU
Apoapsis: 405,696 km
0.0027 AU
Semi-major axis: 384,399 km
0.
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Delta Octantis has the distinction of being Saturn's southern pole star.

[ edit ] Saturn's natural satellites
Janus' group | Mimas | Enceladus | Tethys | Dione | Rhea | Titan | Hyperion | Iapetus | Inuit group | Gallic group |
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