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Equatorial stars[edit] Equatorial stars of the eastern hemisphere. The equatorial region of the celestial sphere's eastern hemisphere includes 17 navigational stars from Alpheratz in the constellation Andromeda to Denebola in Leo. It also includes stars from the constellations Cetus, Aries, Taurus, Orion, Canis Major and Minor, Gemini, and Hydra.
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 ...
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 ...
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 .
It contains Ursa Major and the Hyades star cluster, among others. The Local Bubble also contains the neighboring G-Cloud, which contains the stars Alpha Centauri and Altair. In the galactic context, the Local Bubble is a small part of the Orion Arm, which contains most stars that we can see without a telescope.
Magnetic declination (also called magnetic variation) is the angle between magnetic north and true north at a particular location on the Earth's surface. The angle can change over time due to polar wandering . Magnetic north is the direction that the north end of a magnetized compass needle points, which corresponds to the direction of the ...
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge due to centrifugal force. As stars are not solid bodies, they can also undergo differential rotation.
The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets (e.g., asteroids ), as well as natural satellites and minor-planet moons .