Heliocentrism, or heliocentricism,[1] is the astronomical Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe model in which the Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7] and planets revolve around a stationary Sun The Sun is the star at the center of the Solar System. It has a diameter of about 1,392,000 kilometers , about 109 times that of Earth, and its mass (about 2 × 1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen, while the rest is at the center of the universe The universe is commonly defined as the totality of everything that exists, including all physical matter and energy, the planets, stars, galaxies, and the contents of intergalactic space, although this usage may differ with the context . The term universe may be used in slightly different contextual senses, denoting such concepts as the cosmos,. The word comes from the Greek Ancient Greek is the historical stage in the development of the Greek language spanning the Archaic , Classical (c. 5th–4th centuries BC), and Hellenistic (c. 3rd century BC – 6th century AD) periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek. Its Hellenistic phase is known as Koine (& (ἥλιος helios In Greek mythology, the sun was personified as Helios . Homer often calls him simply Titan or Hyperion, while Hesiod (Theogony 371) and the Homeric Hymn separate him as a son of the Titans Hyperion and Theia (Hesiod) or Euryphaessa (Homeric Hymn) and brother of the goddesses Selene, the moon, and Eos, the dawn. The names of these three were also "sun" and κέντρον kentron "center"). Historically, heliocentrism was opposed to geocentrism In astronomy, the geocentric model , is the theory, now superseded, that the Earth is the center of the universe and other objects go around it. Belief in this system was common in ancient Greece. It was embraced by both Aristotle (see Aristotelian physics) and Ptolemy, and most, but not all, Ancient Greek philosophers assumed that the Sun, Moon,, which placed the Earth at the center. The notion that the Earth revolves around the Sun was first proposed in the 3rd century BC by Aristarchus of Samos Aristarchus was a Greek astronomer and mathematician, born on the island of Samos, in Greece. He is the first known person to present a heliocentric model of the solar system, placing the Sun, not the Earth, at the center of the known universe. He was influenced by the Pythagorean Philolaus of Croton, but, in contrast to Philolaus, he had both. However, it was not until the 16th century that a fully predictive mathematical model A mathematical model uses mathematical language to describe a system. The process of developing a mathematical model is termed mathematical modelling . Mathematical models are used not only in the natural sciences (such as physics, biology, earth science, meteorology) and engineering disciplines, but also in the social sciences (such as economics, of a heliocentric system was presented, by the Renaissance The Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Florence in the Late Middle Ages and later spreading to the rest of Europe. The term is also used more loosely to refer to the historic era, but since the changes of the Renaissance were not uniform across Europe, this is a general use of the mathematician and astronomer Nicolaus Copernicus Nicolaus Copernicus was a Renaissance astronomer and the first to formulate a comprehensive heliocentric cosmology, which displaced the Earth from the center of the universe, leading to the Copernican Revolution. In the following century, this model was elaborated and expanded by Johannes Kepler Johannes Kepler was a German mathematician, astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. They also provided one of the and supporting observations made using a telescope A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century. "Telescopes" can refer to a whole range of instruments operating in most regions of the were presented by Galileo Galilei Galileo Galilei was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism. Galileo has been called the "father of modern observational astronomy,".
Beginning with the observations of William Herschel Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a British astronomer, technical expert, and a composer. Born in Hannover, Wilhelm first followed his father into the Military Band of Hannover, but emigrated to Britain at age 19. Herschel became most famous for the discovery of the planet Uranus in addition to two of, astronomers began to realise that the sun was not the center of the universe and by the 1920s Edwin Hubble Edwin Powell Hubble was an American astronomer who profoundly changed our understanding of the universe by demonstrating the existence of galaxies other than our own, the Milky Way. He also discovered that the degree of "Doppler shift" (specifically "redshift") observed in the light spectra from other galaxies increased in had shown that it was part of a galaxy A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference to the Milky Way galaxy that was only one of many billions.
Early developments
To anyone who stands and looks at the sky, it seems clear that the Earth stays in one place while everything in the sky rises in the east and sets in the west once a day. Observing over a longer time, one sees more complicated movements. The Sun makes a slower circle eastward over the course of a year; the planets A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.[a] have similar motions, but they sometimes move in the reverse direction for a while (retrograde motion).
As these motions became better understood, more elaborate descriptions were required, the most famous of which was the geocentric Ptolemaic system, which achieved its full expression in the 2nd century. The Ptolemaic system was a sophisticated astronomical system that managed to calculate the positions for the planets to a fair degree of accuracy.[2] Ptolemy himself, in his Almagest Almagest is the Latin form of the Arabic name of a mathematical and astronomical treatise proposing the complex motions of the stars and planetary paths, originally written in Greek as Μαθηματικἠ Σύνταξις (Mathematikē Sýntaxis, Mathematical Treatise; later titled Hē Megálē Sýntaxis, The Great Treatise) by Ptolemy of, points out that any model for describing the motions of the planets is merely a mathematical device, and since there is no actual way to know which is true, the simplest model that gets the right numbers should be used.[3] However, he rejected the idea of a spinning earth as absurd since it would create huge winds. His planetary hypotheses Claudius Ptolemaeus , known in English as Ptolemy (pronounced /ˈtɒləmɪ/), was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer and a poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in were sufficiently real that the distances of moon, sun, planets and stars could be determined by treating orbits' celestial spheres The celestial spheres, or celestial orbs, were the fundamental celestial entities of the cosmological celestial mechanics first invented by Eudoxus, and developed by Aristotle, Ptolemy, Copernicus and others. In this celestial model the stars and planets are carried around by being embedded in rotating spheres made of an aetherial transparent as contiguous realities. This made the stars' distance less than 20 Astronomical Units An astronomical unit is a unit of length equal to about 149,597,871 kilometres (92,955,807 miles). It is defined by the International Astronomical Union, and is defined as the mean distance between the Earth and the Sun over one Earth orbit[4]—a clear regression, since Aristarchus's heliocentric scheme had centuries earlier necessarily placed the stars at least two orders of magnitude more distant.
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... which helped him confirm Copernicus' theory of heliocentrism (and, thus, be tried by the Inquisition and spend the rest of his life under house arrest). ...
