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In Greek antiquity the ideas of celestial spheres and rings first appeared in the cosmology of Anaximander in the early 6th century BC. [7] In his cosmology both the Sun and Moon are circular open vents in tubular rings of fire enclosed in tubes of condensed air; these rings constitute the rims of rotating chariot-like wheels pivoting on the Earth at their centre.
In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (from Ancient Greek แผπฮฏκυκλος (epíkuklos) 'upon the circle', meaning "circle moving on another circle") [1] was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets.
This globe is an interesting example of how celestial globes demonstrate both the scientific and the artistic talents of those who make them. All forty-eight classical constellations used in Ptolemy's Almagest are represented on the globe, meaning it could then be used in calculations for astronomy and astrology, such as navigation, time ...
The use of astronomical symbols for the Sun and Moon dates to antiquity. The forms of the symbols that appear in the original papyrus texts of Greek horoscopes are a circle with one ray for the Sun and a crescent for the Moon. [3] The modern Sun symbol, a circle with a dot (โ), first appeared in Europe in the Renaissance. [3]
The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun. [ 1 ] [ 2 ] [ a ] It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
The cross-in-a-circle was interpreted as a solar symbol derived from the interpretation of the disc of the Sun as the wheel of the chariot of the Sun god. [2] Wieseler (1881) postulated an (unattested) Gothic rune hvel ("wheel") representing the solar deity by the "wheel" symbol of a cross-in-a-circle, reflected by the Gothic letter hwair (๐).
The year is usually represented by the 12 signs of the zodiac, arranged either as a concentric circle inside the 24-hour dial, or drawn onto a displaced smaller circle, which is a projection of the ecliptic, the path of the Sun and planets through the sky, and the plane of the Earth's orbit.
The project received one correction from the Director of the Observatory, who noted in 1872 that the signs of the zodiac on the band around the equator of the sphere should actually be on an ecliptic circle. [5]