Apparent angular position of any star in the sky; point on the celestial sphere
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Star position" – news · newspapers · books · scholar · JSTOR(March 2023) (Learn how and when to remove this message)
The equatorial coordinate system on the celestial sphere
Star position is the apparent angular position of any given star in the sky, which seems fixed onto an arbitrary sphere centered on Earth. The location is defined by a pair of angular coordinates relative to the celestial equator: right ascension (α) and declination (δ). This pair based the equatorial coordinate system.
While δ is given in degrees (from +90° at the north celestial pole to −90° at the south), α is usually given in hour angles (0 to 24 h). This is due to the observation technique of star transits, which cross the field of view of telescope eyepieces due to Earth's rotation. The observation techniques are topics of positional astronomy and of astrogeodesy.
Ideally, the Cartesian coordinate system (α, δ) refers to an inertial frame of reference. The third coordinate is the star's distance, which is normally used as an attribute of the individual star.
The following factors change star positions over time:
axial precession and nutation – slow tilts of Earth's axis with rates of 50 arcseconds and 2 arcseconds respectively, per year;
the aberration and parallax – effects of Earth's orbit around the Sun; and
the proper motion of the individual stars.
The first and second effects are considered by so-called mean places of stars, contrary to their apparent places as seen from the moving Earth. Usually the mean places refer to a special epoch, e.g. 1950.0 or 2000.0. The third effect has to be handled individually.
The star positions (α, δ) are compiled in several star catalogues of different volume and accuracy. Absolute and very precise coordinates of 1000-3000 stars are collected in fundamental catalogues, starting with the FK (Berlin ~1890) up to the modern FK6.
Relative coordinates of numerous stars are collected in catalogues like the Bonner Durchmusterung (Germany 1859-1863, 342,198 rough positions[1]), the SAO catalogue (USA 1966, 250.000 astrometric stars) or the Hipparcos and Tycho catalogue (110.000 and 2 million stars by space astrometry).
^F.W.A. Argelander (1863). Bonner Sternverzeichnis - Dritte Section. Adolph Marcus. p. vii.
Starposition is the apparent angular position of any given star in the sky, which seems fixed onto an arbitrary sphere centered on Earth. The location...
planetary position tables, star tables, and star maps for use by both amateur and professional astronomers. More recently, computerized star maps have...
exact position is inside of it. The accuracy of the sights is indicated by the size of the triangle. Joshua Slocum used both noon sight and star sight...
players on court per team, each assigned to positions. Historically, these players have been assigned to positions defined by the role they play on the court...
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated...
that could compute the positions of the stars. They built the first large observatory research institutes, mainly to produce Zij star catalogues. Among these...
three-starpositions in the United States military establishment, for the position has historically served as a stepping stone to a four-starposition. As...
The PPM Star Catalogue (Positions and Proper Motions Star Catalogue) is the successor of the SAO Catalogue. It contains precise positions and proper motions...
distinction is made between the mean position, apparent position and topocentric position of an object. The mean position of a star (relative to the observer's...
renegotiate the royalty arrangements from a position of strength. In the late 1980s, Marvel dropped a new Star Wars comic it had in development, which was...
helped StarPlus to regain their position into Top 10. On week 12 of 2020, while it dropped to fifth position in Hindi GEC while overall at sixth position in...
A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured...
standard star catalogue in the Western and Arab worlds for over eight centuries. The Islamic astronomer al-Sufi updated it in 964, and the starpositions were...
in the horizontal coordinate system, a star'sposition differs from observer to observer based on their positions on the Earth's surface, and is continuously...
obtained using star trackers. Global navigation satellite systems (GNSS) allow specialized radio receivers to determine their 3-D space position, as well as...
football, each of the 11 players on a team is assigned to a particular position on the field of play. A team is made up of one goalkeeper and ten outfield...
straight up at or near the zenith, and used for precision measurement of starpositions, to simplify telescope construction, or both. The NASA Orbital Debris...
Critical Positions on Star Trek. Boulder, Colorado: Westview Press. ISBN 0-8133-2899-3. Shatner, William; Kreski, Chris (October 1993). Star Trek Memories...
in 1779, hoping to find a near star paired with a distant star so he could measure the near star's changing position as the Earth orbited the Sun (measure...
A clock position, or clock bearing, is the direction of an object observed from a vehicle, typically a vessel or an aircraft, relative to the orientation...
approval comes mostly from its Working Group on Star Names, which has been publishing a "List of IAU-approved Star Names" since 2016. As of April 2022, the list...
bondage position in which a person is bound into a ball position with the knees against the shoulders. A ball position (also called a fetal position) can...
Global Information
