Spherical astronomy

The spherical astronomy deals with the two-dimensional survey of the sky and the associated calculations, cosmic star positions and reference systems. You can see it from that the various celestial bodies are quite different far away, and treated the stars as points on an imaginary unit sphere (the " celestial sphere ") that surrounds the earth. The third dimension is the radius of the unit sphere.

Basis of astronomy

The main results of spherically - astronomical measurements - covering substantially the geometric part of the field of astronomy - are the celestial coordinates right ascension and declination of the stars and their changes over time. These measurements of places, by their speeds are the basis of positional astronomy and is closely related to the methods of astrometry and trigonometry together.

This form of astronomy was well into the modern era, the only possible, because the determination of the distance of celestial bodies and their radiation before the 18th century was hardly possible. With the invention of the telescope, the spherical astronomy took a hitherto unimaginable prosperity. They increased their accuracy of about 0.02 ° ( freiäugig ) to ten thousand times ( about 0.01 " ) and can be applied to very faint stars and distant galaxies for approximately 100 years.

This was the spherical astronomy as the basis of all astronomical progress - especially in celestial mechanics - and for our present knowledge of the structure of the universe. The increased accuracy of the direction of measurement allowed astronomers to determine the distance also " fixed stars " ( for the first time in 1838 by Bessel's measurement of an annual stellar parallax ).

Until about 1870, when the astrophysics began to be established after the invention of photography and spectral analysis, made ​​astrometry and spherical astronomy from the majority of scientific astronomy.

Development since about 1900

The reorientation of the Astronomy of geometric on increasing physical methods amounted to a revolution of the entire astronomy, which was reflected in their popular astronomy and also in the construction of many new observatories - in central Europe, for example, the Vienna University Observatory and the Astrophysical Institute Potsdam. But attention was paid between 1880 and 1920 severely out that positional astronomy was still possible - for example with the development of high-precision meridian circles and zenith telescopes. The theoretical part of the subject area addressed during which the definition of more accurate reference systems - which ultimately became the basis of space travel - and 1900 with the irregularities of the earth's rotation (see also IPMS ) and the polar motion.

Nevertheless, in 1950 and 1975, less than a fifth of the astronomers were between working in geometric methods, however, many surveyors worked since development of satellite geodesy on related topics. This changed rapidly around 1990, when the production of optoelectronic sensors was cheaper and the potential of CCD has been fully recognized. There are now fully automatic meridian circles and astrometry and a but further increase the measurement accuracy, to 0.001 " is enough for Hipparcos. With the radio interferometry (see VLBI ) can coordinate even far more accurate and determine changes in the earth up to the millimeter range. This allows

  • Detailed studies in the field of geophysics, and
  • The body and trains in the solar system,
  • Detailed movements in our galaxy,
  • Further, the discovery of hundreds of exoplanets yet

And further improvements to at least 10 times by future satellites and space-based measurement campaigns such as GAIA, Galileo and others.

Leibniz Institute for Astrophysics Potsdam Very Long Baseline Interferometry Gaia (spacecraft)
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