Very beautiful and rare star globe / celestial globe in wooden box for marine navigation.
The celestial globe is an indispensable navigation aid for shipping, along with the sextant and the ship's chronometer.
The celestial globe shows the starry sky with the constellations and fixed stars mirrored on a sphere, so that an exact determination of position is possible over several scales with angle graduation.
The representation/projection of the stars and constellations on a sphere has the advantage that the starry sky can be projected realistically without distortion. The sphere can be rotated according to the local hour angle and the world axis can be tilted according to the geographical latitude.
In two-dimensional images, distortions basically occur; a precise representation and determination of position in a planar form is not possible.
Why Starglobe or Starfinder?
Starglobe and starfinder are used to convert alternately celestial to horizontal coordinates of a star.
Where is this or that star now at my position? The celestial coordinates: local hour angle and declination are found in the Nautical Almanach. Adjust Starglobe or -finder accordingly. Now read the horizontal coordinates: azimuth or direction and height of the star.
Conversely the celestial coordinates and name of the unknown star can be concluded from azimuth and height. This simplifies astronavigation with the sextant:
- Observing an unknown star between cloud snatches. Sextant height and approximate direction can be determined. Now it is possible to find the celestial coordinates and with them the name of the star to calculate a line of position.
- The planet Venus is invisible in the daytime. Use Starglobe or -finder to determine direction and height. Now Venus will appear when observing through the sextant telescope.
Also, many navigational calculators include easy to use programs to solve these problems.