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Since the planisphere shows the celestial sphere in a printed flat, there is always considerable distortion. Planispheres, like all charts, are made using a certain projection method. For planispheres there are two major methods in use, leaving the choice with the designer. One such method is the polar azimuthal equidistant projection. Using ...
"there is no convincing evidence that Ptolemy or any of his predecessors knew about the planispheric astrolabe". [14] In chapter 5.1 of the Almagest, Ptolemy describes the construction of an armillary sphere, and it is usually assumed that this was the instrument he used. Astrolabes continued to be used in the Byzantine Empire.
Planisphere or Planisphaerium, a 2nd-century AD book by Claudius Ptolemy about mapping the celestial sphere onto a flat plane using the stereographic projection to make a star chart; Planispheric astrolabe, a device consisting of a planisphere joined to a dioptra, used for observing stars and performing astronomical calculations
The title can be translated as "celestial plane" or "star chart". In this work Ptolemy explored the mathematics of mapping figures inscribed in the celestial sphere onto a plane by what is now known as stereographic projection. This method of projection preserves the properties of circles.
The Treatise is considered the "oldest work in English written upon an elaborate scientific instrument". [1] It is admired for its clarity in explaining difficult concepts – although modern readers lacking an actual astrolabe may find the details of the astrolabe difficult to understand.
The sphere, with various loxodromes shown in distinct colors. The loxodromes of the sphere map to curves on the plane of the form = /, where the parameter a measures the "tightness" of the loxodrome. Thus loxodromes correspond to logarithmic spirals. These spirals intersect radial lines in the plane at equal angles, just as the loxodromes ...
The Madison Square Garden (MSG) Sphere at the Venetian Resort in Las Vegas has LED lights that can create these large-scale projections. It has been filmed projecting the image of a gigantic ...
Mercator's 1569 map was a large planisphere, [3] i.e. a projection of the spherical Earth onto the plane. It was printed in eighteen separate sheets from copper plates engraved by Mercator himself. [4]