Astrodicticum simplex

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The Jenense Collegium after the copper engraving by Johann Dürr in Weigel's writing “ Himmelsspiegel ” from 1661. Astronomical instruments are shown in the foreground. On the right in the row of astronomical instruments you can see a celestial globe with an astrodicticum simplex .

The Astrodicticum simplex (" simple star pointer ", from Greek ἄστρον ástron " star ", δεικτικός dhiktikós "display" and Latin simplex "simple") is an astronomical instrument developed by Erhard Weigel for university teaching purposes , which is used to find stars and Should facilitate star constellations in the starry sky .

construction

An Astrodicticum simplex consists of a "pointer" and a sighting device (sighting ruler) mounted parallel to this pointer, which are connected to one another via a metal arc of a quarter circle and are mounted on a celestial globe .

Erhard Weigel himself described the instrument as follows:

"Astrodicticum Simplex. A star-wise man / knowing all the stars in front of you without prior notice. If a regul is to be applied to the celestial sphere placed / that / if the regul is pointed at the coveted star in the sky / a circular bow on the instrument on the celestial sphere shows what a star is. "

- Erhard Weigel : Mathematical Art Exercises , 1669

functionality

The aim is to align the sight ruler with the star in the starry sky indicated by the "pointer" on the celestial globe, in order to enable inexperienced observers to find the respective star in the starry sky.

For stars in the starry sky at which the sighting ruler is aimed, the respective stars with their names are then identified by the "pointer" on the celestial globe. Conversely, if you point the “pointer” at a star on the celestial globe that you want to track down and observe in the starry sky, the sighting ruler then provides the position of the star you are looking for and points in its direction.

The alignment of the Astrodicticum simplex can be checked with the help of a guide star of suitable brightness, which is fixed by an experienced observer in the direction of the sight ruler. The “pointer” of the Astrodicticum simplex must then be aimed precisely at the image of this star on the celestial globe. If there is only a small angular distance - which is the case after just a few minutes of observation, the stars depicted on the celestial globe and the corresponding stars in the starry sky drift apart.

The observation of stars with the help of the Astrodicticum simplex requires an accurate image of the starry sky on the celestial globe used and also requires precise time synchronization between the celestial globe and the starry sky. While observing the starry sky with the aid of the Astrodicticum simplex, constant tracking of the celestial globe is necessary.

Today's meaning

According to Johann Dorschner, the Astrodicticum simplex is probably the only device invented by Erhard Weigel that is still produced today - in a modified form.

Naming

Florian Freistetter named his science blog Astrodicticum simplex at ScienceBlogs , based on Erhard Weigel's commitment as a “popularizer of science” after this instrument.

literature

  • Erhard Weigel: Speculum Uranicum Aquilae Romanae Sacrum, That is / Him [m] els mirror. Franckfurt, Jehna 1661
  • Erhard Weigel: Mathematical Art Exercises. in: Erhardi Weigelii PP Idea Matheseos Universae: cum Speciminibus Inventionum Mathematicarum. Jenae 1669, pp. 69-84
  • Reinhard E. Schielicke, Klaus-Dieter Herbst, Stefan Kratochwil (eds.): Erhard Weigel - 1625 to 1699. Baroque patriarch of the early German Enlightenment . Contributions to the colloquium on the occasion of the 300th anniversary of his death on March 20, 1999 in Jena (Acta Historica Astronomiae 7). Thun, Frankfurt am Main 1999. ( Online , accessed February 1, 2016)

Web links

Individual evidence

  1. ↑ Erhard Weigel: Mathematical Art Exercises Jenae 1669, p. 74 , accessed on January 25, 2016
  2. ↑ Reinhard E. Schielicke, Klaus-Dieter Herbst, Stefan Kratochwil (ed.): Erhard Weigel - 1625 to 1699. Baroque patriarch of the early German Enlightenment . Page 25
  3. ↑ Erhard Weigel in the English Wikipedia , accessed on January 25, 2016
  4. ↑ Florian Freistetter : What is an "Astrodicticum Simplex"? , accessed January 25, 2016