Sky sight

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The term sky view is a term used in astronomical phenomenology . It means calculating the exact position of the starry sky above the horizon of the observer at a certain "date" ( date D and time ( true local time ) T ) as well as for a certain observation point (geographical latitude B and longitude L ) .

This is done with the formulas of trigonometry (see spherical astronomy and astronomical triangle ), whereby the sidereal time must be calculated on site beforehand .

Note : The starry sky does not rotate relative to the observer in exactly 24 hours, but about four minutes faster. The cause is the annual earth orbit around the sun - as well as the fact that clocks are set according to the daytime stars and not according to the stars. As a result of this difference between civil and sidereal time, the starry sky can be seen "rotated further" every day at 3:56 minutes (or about one degree) in the evening at the same time, which is exactly one revolution of the earth in one year .

The "sight problem " (naming by H.Mucke ) corresponds - with other given sizes - to a " dating problem " or a " locating problem ":

  1. Sky view: the location (B, L) is given, the time (D, T) is variable
  2. Location problem: the view of the sky is given, the corresponding location is sought (B, L)
  3. Dating problem: the sky, place and time are given, the date (D) is sought.

There is an equivalence between the time (local time) and the geographical longitude - that is, the current view of the sky is at two locations of one degree of latitude, but different longitudes are different, but are (almost) identical at the same local time on the respective date. This applies to all 3 of the above tasks.

One tool for determining the view of the sky is a rotatable star map .

literature

  • Karl-Heinz Bernhardt: Layered structure of the atmosphere, view of the sky and cloud shape . In: Werner Wehry, Franz J. Ossing (Ed.): Clouds, Painting, Climate in Past and Present . German Meteorolog. Ges., Berlin 1997. ISBN 3-928903-13-6 , pp. 99-124.