Celestial pole in the context of "Celestial sphere"

Geocentrism is a superseded astronomical model description of the Universe with Earth at the center. It is also known as the geocentric model, often exemplified specifically by the Ptolemaic system. Under most geocentric models, the Sun, the Moon, stars, and planets all orbit Earth. The geocentric model was the predominant description of the cosmos in many European ancient civilizations, such as those of Aristotle in Classical Greece and Ptolemy in Roman Egypt, as well as during the Islamic Golden Age.

Two observations supported the idea that Earth was the center of the Universe. First, from anywhere on Earth, the Sun appears to revolve around Earth once per day. While the Moon and the planets have their own motions, they also appear to revolve around Earth about once per day. The stars appeared to be fixed on a celestial sphere rotating once each day about an axis through the geographical poles of Earth. Second, Earth seems to be unmoving from the perspective of an earthbound observer; it feels solid, stable, and stationary.

In astronomy, diurnal motion (from Latin diurnus 'daily', from Latin diēs 'day') is the apparent motion of celestial objects (e.g. the Sun and stars) around Earth, or more precisely around the two celestial poles, over the course of one day. It is caused by Earth's rotation around its axis, so almost every star appears to follow a circular arc path, called the diurnal circle, often depicted in star trail photography.

The time for one complete rotation is 23 hours, 56 minutes, and 4.09 seconds – one sidereal day. The first experimental demonstration of this motion was conducted by Léon Foucault. Because Earth orbits the Sun once a year, the sidereal time at any given place and time will gain about four minutes against local civil time, every 24 hours, until, after a year has passed, one additional sidereal "day" has elapsed compared to the number of solar days that have gone by.

The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets (e.g., asteroids), as well as natural satellites and minor-planet moons.

A pole star is a visible star that is approximately aligned with the axis of rotation of an astronomical body; that is, a star whose apparent position is close to one of the celestial poles. On Earth, a pole star would lie directly overhead when viewed from the North or the South Pole.

Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude 2 star aligned approximately with its northern axis that serves as a pre-eminent star in celestial navigation, and a much dimmer magnitude 5.5 star on its southern axis, Polaris Australis (Sigma Octantis).

A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare). Others are called seasonal stars.

All circumpolar stars lie within a circumpolar circle whose size is determined by the observer's latitude. Specifically, the angular measure of the radius of this circle equals the observer's latitude. The closer the observer is to the North or South Pole, the larger its circumpolar circle.

The Wǔfāng Shàngdì (Chinese: 五方上帝 "Five Regions' Highest Deities" or "Highest Deities of the Five Regions"), or simply Wǔdì (五帝; "Five Deities") or Wǔshén (五神; "Five Gods") are, in Chinese canonical texts and common Chinese religion, the fivefold manifestation of the supreme God of Heaven (天; Tiān, or equivalently 上帝; Shàngdì). This theology dates back at least to the Shang dynasty. Described as the "five changeable faces of Heaven", they represent Heaven's cosmic activity which shapes worlds as 壇; tán, "altars", imitating its order which is visible in the starry vault, the north celestial pole and its spinning constellations. The Five Deities themselves represent these constellations. In accordance with the Three Powers (三才; Sāncái) they have a celestial, a terrestrial and a chthonic form. The Han Chinese identify themselves as the descendants of the Red and Yellow Deities.

They are associated with the five colors, the five phases of the continuous creation (五行; Wuxing), the five classical planets of the Solar System and the five constellations rotating around the celestial pole, the five sacred mountains and five directions of space (their terrestrial form), and the five Dragon Gods (龙神; Lóngshén) who represent their mounts, that is to say the material forces they preside over (their chthonic form). They have also been defined simply as five special forms of the worship of the God of Heaven, different "accesses" or perspectives, suitable for different situations, to serve Heaven.