“astrometry”的概念、定义、翻译、参考文献-科学参考

astrometry

Physics

The branch of astronomy concerned with the measurement of the positions of the celestial bodies on the celestial sphere.

Astronomy

The measurement of positions, parallaxes, and proper motions on the sky. It can be divided broadly into two categories: global and small-field astrometry. Global astrometry is concerned with mapping and cataloguing positions and motions over large areas of sky. It was traditionally based on optical observations made with meridian instruments. A stellar reference frame of bright stars is derived from such observations, which can then be interpolated to fainter stars. The accuracy of all ground-based optical astrometry is limited by thermal and mechanical instabilities in the telescopes, but also mainly by uncertainties in the amount of atmospheric refraction. The Hipparcos satellite was launched in 1989 to overcome these limitations followed by Gaia in 2013. Global astrometry at radio wavelengths is carried out by interferometers, with both short and very long baselines.
In small-field astrometry, relative positions are measured within the area observable with long-focus telescopes. Its main aims are to measure relative proper motions and trigonometric parallaxes of stars, to discover astrometric binaries, and to identify faint optical counterparts of objects detected at other wavelengths.

Space Exploration

The measurement of the precise positions of stars, planets, and other bodies in space. Such information is needed for practical purposes including accurate timekeeping, surveying and navigation, and calculating orbits and measuring distances in space. Astrometry is not concerned with the surface features or the physical nature of the body under study.
Before telescopes, astronomical observations were simple astrometry. Precise astrometry has shown that stars are not fixed in position but have a proper motion caused as they and the Sun orbit the Milky Way galaxy. The nearest stars also show parallax (apparent change in position), from which their distances can be calculated. Above the distorting effects of the atmosphere, satellites such as Hipparcos, launched by the European Space Agency in 1989, made even more precise measurements than ground telescopes, so refining the distance scale of space.

单词	astrometry
释义	astrometry Physics The branch of astronomy concerned with the measurement of the positions of the celestial bodies on the celestial sphere. Astronomy The measurement of positions, parallaxes, and proper motions on the sky. It can be divided broadly into two categories: global and small-field astrometry. Global astrometry is concerned with mapping and cataloguing positions and motions over large areas of sky. It was traditionally based on optical observations made with meridian instruments. A stellar reference frame of bright stars is derived from such observations, which can then be interpolated to fainter stars. The accuracy of all ground-based optical astrometry is limited by thermal and mechanical instabilities in the telescopes, but also mainly by uncertainties in the amount of atmospheric refraction. The Hipparcos satellite was launched in 1989 to overcome these limitations followed by Gaia in 2013. Global astrometry at radio wavelengths is carried out by interferometers, with both short and very long baselines. In small-field astrometry, relative positions are measured within the area observable with long-focus telescopes. Its main aims are to measure relative proper motions and trigonometric parallaxes of stars, to discover astrometric binaries, and to identify faint optical counterparts of objects detected at other wavelengths. Space Exploration The measurement of the precise positions of stars, planets, and other bodies in space. Such information is needed for practical purposes including accurate timekeeping, surveying and navigation, and calculating orbits and measuring distances in space. Astrometry is not concerned with the surface features or the physical nature of the body under study. Before telescopes, astronomical observations were simple astrometry. Precise astrometry has shown that stars are not fixed in position but have a proper motion caused as they and the Sun orbit the Milky Way galaxy. The nearest stars also show parallax (apparent change in position), from which their distances can be calculated. Above the distorting effects of the atmosphere, satellites such as Hipparcos, launched by the European Space Agency in 1989, made even more precise measurements than ground telescopes, so refining the distance scale of space.
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