A Description of the Markings Observed on the Planet Venus (or my First Discovery) Which we Call Celidography
The first opportunity for observation.
Other observations of the lun1ar marking called Plato, accomplished in the same period, 1725 and 1727.
Observations of Venus undertaken in 1726.
Selection of the sites to perform the observations, first at Rome and then at Albano, performed with 100-palm telescopes.
Selection of the time, and types of eyepieces.
The first observations undertaken in February disclose markings on the glob of Venus (called Hesperus during its evening elongation from the Sun), and their rotation round the planet’s axis in 24 days, from which is revealed the Celidography of more than half of Venus’ globe.
The circumpolar markings of that planet, which could not be described from the February and March observations as they were not lit by the Sun, were revealed from other observations made in May and June 1726 when the South Pole was presented to the Sun and to our gaze, and in July 1727 when the North Pole was presented, to complete the Celidography of the whole globe.
The possibility of more exact observations and descriptions if, at times indicated here and more fully explained in the last chapter, telescopes are directed at that planet.
The reason for the term Celidography being used for this description.
Precautions to be taken to give a clearer view of the markings; and concerning their likeness to the markings generally called “maria” on the Moon.
KeywordsNorth Pole South Pole 20th Degree Solar Illumination Object Glass
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