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Pole star. 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 .
Polaris Aa is an evolved yellow supergiant of spectral type F7Ib with 5.4 solar masses ( M☉ ). It is the first classical Cepheid to have a mass determined from its orbit. The two smaller companions are Polaris B, a 1.39 M☉ F3 main-sequence star orbiting at a distance of 2,400 astronomical units (AU), [17] and Polaris Ab (or P), a very close ...
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north. It uses the right-handed convention ...
The north and south celestial poles are the two points in the sky where Earth 's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively. As Earth spins on its axis, the two celestial poles ...
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 Polaris, Earth turns counterclockwise . The North Pole, also known as the Geographic North ...
Axial precession. Precessional movement of Earth. Earth rotates (white arrows) once a day around its rotational axis (red); this axis itself rotates slowly (white circle), completing a rotation in approximately 26,000 years [1] In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical ...
Ursa Minor (Latin: 'Lesser Bear', contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern sky.As with the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the North American name, Little Dipper: seven stars with four in its bowl like its partner the Big Dipper.
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 ( / poʊˈlɛərɪs ɔːˈstreɪlɪs / ). [10] The star is positioned one degree away from the southern ...