| 摘要 |
<p>The disclosed planisphere has three superimposed sheets (1, 2, 3). The lower sheets represent the two planispheres, the terrestrial (1) and the celestial (2) planispheres which are joined by a common rotation center (4) coinciding with the poles. The upper sheet (3), which is transparent as is (2), is excentric with respect to the prior ones since its rotation center is the pole of the ecliptic (5) situated in the parallel 66.5 of the celestial planisphere (2). Said sheet (3) is intended to mark out on the terrestrial planisphere (1) the areas which are illuminated (6) or which are not illuminated (7) by the sun (8). It has scientific-didactic applications since it simulates the night-day succession and the process of the seasons, while relating the positon of the stars and the height of the sun at midday with respect to places on earth. It also has industrial applications since it can be used as a watch face. Alternatives of said planisphere are obtained by suppressing any one of its three components or by providing said components as the surfaces of spherical caps.</p> |
