Illustration of the use of optical wavelength interferometry to determine precise positions of stars. Courtesy NASA/JPL-Caltech.

Astrometry is a branch of astronomy that deals with the positions of stars and other celestial bodies, their distances and movements. Image File history File links Interferometric_astrometry. ... Image File history File links Interferometric_astrometry. ... A giant Hubble mosaic of the Crab Nebula, a supernova remnant. ... This article is about the astronomical object. ... See lists of astronomical objects for a list of the various lists of astronomical objects in Wikipedia. ...

It is one of the oldest subfields of the science, the successor to the more qualitative study of positional astronomy. Astrometry dates back at least to Hipparchus, who compiled the first catalogue of stars visible to him and in doing so invented the brightness scale basically still in use today. Modern astrometry was founded by Friedrich Bessel with his Fundamenta astronomiae, which gave the mean position of 3222 stars observed between 1750 and 1762 by James Bradley. Part of a scientific laboratory at the University of Cologne. ... Positional astronomy is the study of the positions of celestial objects. ... Hipparchus. ... In astronomy, many stars are referred to simply by catalogue numbers. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... Friedrich Wilhelm Bessel (July 22, 1784 – March 17, 1846) was a German mathematician, astronomer, and systematizer of the Bessel functions (which, despite their name, were discovered by Daniel Bernoulli). ... James Bradley (March 1693 – July 13, 1762) was an English astronomer, Astronomer Royal from 1742. ...

Apart from the fundamental function of providing astronomers with a reference frame to report their observations in, astrometry is also fundamental for fields like celestial mechanics, stellar dynamics and galactic astronomy. In observational astronomy, astrometric techniques help identify stellar objects by their unique motions. It is instrumental for keeping time, in that UTC is basically the atomic time synchronized to Earth's rotation by means of exact observations. Astrometry is also involved in creating the cosmic distance ladder because it is used to establish parallax distance estimates for stars in the Milky Way. An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... A frame of reference in physics is a set of axes which enable an observer to measure the aspect, position and motion of all points in a system relative to the reference frame. ... Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. ... Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. ... Galactic astronomy is the study of galaxies, their formation, structure, components, dynamics, interactions, and the range of forms they take. ... Mayall telescope at Kitt Peak National Observatory Observational astronomy is a division of the astronomical science that is concerned with getting data, in contrast with theoretical astrophysics which is mainly concerned with finding out the measureable implications of physical models. ... A pocket watch, a device used to keep time There are two distinct views on the meaning of time. ... UTC redirects here. ... International Atomic Time (TAI, from the French name Temps Atomique International) is a high-precision atomic time standard that tracks proper time on Earths geoid. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... This article is in need of attention from an expert on the subject. ... This does not cite its references or sources. ... It has been suggested that Andromeda-Milky Way collision be merged into this article or section. ...

Advances in astrometry

• Sundials were effective at measuring time.
• Astrolabes were invented for measuring celestial angles.
• Astrometric applications led to the development of spherical geometry
• Careful measurement of planetary motions by Tycho Brahe, followed by analysis by Johannes Kepler proved the Copernican principle, that Earth revolves about the Sun.
• The sextant dramatically improved measurement of celestial angles.
• James Bradley measured stellar aberration with a precise transit telescope.
• The advent of photography and the Astrograph in the late 19th century allows the imaging of a much larger number of fainter stars for astrometric measurement and position archiving in large photographic catalogs.
• The development of charge coupled devices (CCDs), and their adoption by astronomers in the 1980s, improved the precision of professional astrometric work.
• The development of inexpensive CCDs, software, and telescopes allowed for large-scale amateur astrometric observation of minor planets.
• From 1989 to 1993, the European Space Agency's Hipparcos satellite performed astrometric measurements resulting in a catalogue of positions accurate to 20-30 milliarcsec for over a million stars.

Astronomers use astrometric techniques for the tracking of near-Earth objects. It has been also been used to detect extrasolar planets by measuring the displacement they cause in their parent star's apparent position on the sky, due to their mutual orbit around the center of mass of the system. NASA's planned Space Interferometry Mission (SIM PlanetQuest) will utilize astrometric techniques to detect terrestrial planets orbiting 200 or so of the nearest solar-type stars. Wall sundial Wall sundial in Warsaws Old Town A sundial is device that measures time by the position of the Sun. ... A 16th century astrolabe. ... Spherical geometry is the geometry of the two-dimensional surface of a sphere. ... ... Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague Tycho Brahe, born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish nobleman from the region of Scania (in modern-day Sweden), best known today as an early astronomer, though in his lifetime he was also... Johannes Kepler (December 27, 1571 – November 15, 1630) was a German Lutheran mathematician, astronomer and astrologer, and a key figure in the 17th century astronomical revolution. ... The Copernican principle is the philosophical statement that no special observers should be proposed. ... The Sun is the star at the center of the Solar System. ... A sextant is a measuring instrument generally used to measure the angle of elevation of a celestial object above the horizon. ... An angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle. ... James Bradley (March 1693 – July 13, 1762) was an English astronomer, Astronomer Royal from 1742. ... The aberration of light (also referred to as astronomical aberration or stellar aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects. ... A Transit mount is a system where a telescope can move in altitude (North-South), but not in azimuth (East-West). ... HAHA, Ive deleted all KISS MY ASS>< ... Astrograph in Bolivia. ... A charge-coupled device (CCD), is an integrated circuit containing an array of linked, or coupled, capacitors. ... It has been suggested that this article or section be merged with Skygazing. ... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... Hipparcos (for High Precision Parallax Collecting Satellite) was an astrometry mission of the European Space Agency (ESA) dedicated to the measurement of stellar parallax and the proper motions of stars. ... Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earths orbit and which may therefore pose a collision danger. ... Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ... Artists concept of Space Interferometry Mission spacecraft The Space Interferometry Mission (SIM), also called SIM PlanetQuest, is a NASA instrument originally expected to be launched in December of 2011; however due to budget cuts it will now launch no sooner than between October 2014 and April 2015. ... Artists concept of Space Interferometry Mission spacecraft The Space Interferometry Mission (SIM), also called SIM PlanetQuest, is a NASA instrument expected to be launched in 2011. ... A terrestrial planet or telluric planet is a planet which is primarily composed of silicate rocks. ...

Astrometric measurements are used by astrophysicists to constrain certain models in celestial mechanics. By measuring the velocities of pulsars, it is possible to put a limit on the asymmetry of supernova explosions. Also, astrometric results are used to determine the distribution of dark matter in the galaxy. An astrophysicist is a person whose profession is astrophysics. ... Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. ... Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ... Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... In astrophysics and cosmology, dark matter is matter, not directly observed and of unknown composition, that does not emit or reflect enough electromagnetic radiation to be detected directly, but whose presence can be inferred from gravitational effects on visible matter. ...

Astrometrics

Astrometrics is the science of stellar measurements and motion. Astrometrics was used, during the 1990s, to detect extrasolar gas giants orbiting various solar systems. This was done by observing the "stellar wobble" of a star and calculating what kinds of gravitational forces would cause such motion; it was then determined that planetary forces must be affecting the stars in question. Part of a scientific laboratory at the University of Cologne. ... This article is about the astronomical object. ... Various meters Measurement is the estimation or determination of extent, dimension or capacity, usually in relation to some standard or unit of measurement. ... This article or section is in need of attention from an expert on the subject. ... 1990 (MCMXC) was a common year starting on Monday of the Gregorian calendar. ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... The solar systems four gas giants against the Suns limb, to scale A gas giant (sometimes also known as a Jovian planet after the planet Jupiter) is a large planet that is not primarily composed of rock or other solid matter. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Major features of the Solar System (not to scale, from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth & Moon, and Mars. ... Stellar wobble is the wobble of a star (this wobble is not visibile except via Doppler shifts) when a stars orbit is gravitationally affected by a nearby massive star. ... Gravity is a force of attraction that acts between bodies that have mass. ... In physics, force is an influence that may cause a body to accelerate. ... The eight planets and three dwarf planets of the Solar System. ...

References

• Jean Kovalevsky and P. Kenneth Seidelman, Fundamentals of Astrometry, Cambridge University Press, 2004, ISBN 0-521-64216-7.
• Hall of Precision Astrometry (English). University of Virginia Department of Astronomy. Retrieved on 2006-08-10.

For the Manfred Mann album, see 2006 (album). ... August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian Calendar. ...

In fiction

In the fictional Star Trek: Voyager, the Astrometrics lab is the set for various scenes. Fiction (from the Latin fingere, to form, create) is storytelling of imagined events and stands in contrast to non-fiction, which makes factual claims about reality. ... The starship Voyager (NCC-74656), an Intrepid-class starship. ... In drama, the set (or setting) is the location of a storys action. ... Scene may refer to: Scene (fiction), an element of a larger fictional work such as a play Scene (film), a part of action in a single location in a TV or movie Scene (music), a collection of musical acts that play regularly in one location. ...

See also

• Astrometric binary
• Ephemeris
• Equatorium
• Gaia Probe (ESA -- Planned for 2009-14)
• Hipparcos Space Astrometry Mission (ESA -- 1989-93)
• Spherical astronomy