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Planetary System
A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although such systems may also consist of bodies such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals and circumstellar disks. For example, the Sun together with the planetary system revolving around it, including Earth, form the Solar System. The term exoplanetary system is sometimes used in reference to other planetary systems. Planetary systems are, by convention, named for their host, or parent star, as is the case in our Solar Planetary System, named for its hosting, star, "Sol". Debris disk, Debris disks are known to be common while other objects are more difficult to observe. Of particular interest to astrobiology is the habitable zone of planetary systems where planets could have surface liquid water, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Artist Concept Planetary System
An artist is a person engaged in an activity related to creating art, practicing the arts, or demonstrating the work of art. The most common usage (in both everyday speech and academic discourse) refers to a practitioner in the visual arts only. However, the term is also often used in the entertainment business to refer to actors, musicians, singers, dancers and other performers, in which they are known as ''Artiste'' instead. ''Artiste'' (French) is a variant used in English in this context, but this use has become rare. The use of the term "artist" to describe writers is valid, but less common, and mostly restricted to contexts such as critics' reviews; "author" is generally used instead. Dictionary definitions The ''Oxford English Dictionary'' defines the older, broader meanings of the word "artist": * A learned person or Master of Arts * One who pursues a practical science, traditionally medicine, astrology, alchemy, chemistry * A follower of a pursuit in which skill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the universe by investigating its deterministic conditions and contingent events. As a discipline, astrobiology is founded on the premise that life may exist beyond Earth. Research in astrobiology comprises three main areas: the study of planetary habitability, habitable environments in the Solar System and beyond, the search for planetary biosignatures of past or present extraterrestrial life, and the study of the Abiogenesis, origin and Protocell, early evolution of life on Earth. The field of astrobiology has its origins in the 20th century with the advent of space exploration and the discovery of exoplanets. Early astrobiology research focused on the search for extraterrestrial life and the study of the potential for life to exist on other pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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The Sand Reckoner
''The Sand Reckoner'' (, ''Psammites'') is a work by Archimedes, an Ancient Greek mathematician of the 3rd century BC, in which he set out to determine an upper bound for the number of grains of sand that fit into the universe. In order to do this, Archimedes had to estimate the size of the universe according to the contemporary model, and invent a way to talk about extremely large numbers. The work, also known in Latin as ''Arenarius'', is about eight pages long in translation and is addressed to the Syracusan king Gelo II (son of Hiero II). It is considered the most accessible work of Archimedes.Archimedes, The Sand Reckoner 511 R U, by Ilan Vardi accessed 28-II-2007. Naming large numbers [Baidu] |
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Archimedes
Archimedes of Syracuse ( ; ) was an Ancient Greece, Ancient Greek Greek mathematics, mathematician, physicist, engineer, astronomer, and Invention, inventor from the ancient city of Syracuse, Sicily, Syracuse in History of Greek and Hellenistic Sicily, Sicily. Although few details of his life are known, based on his surviving work, he is considered one of the leading scientists in classical antiquity, and one of the greatest mathematicians of all time. Archimedes anticipated modern calculus and mathematical analysis, analysis by applying the concept of the Cavalieri's principle, infinitesimals and the method of exhaustion to derive and rigorously prove many geometry, geometrical theorem, theorems, including the area of a circle, the surface area and volume of a sphere, the area of an ellipse, the area under a parabola, the volume of a segment of a paraboloid of revolution, the volume of a segment of a hyperboloid of revolution, and the area of a spiral. Archimedes' other math ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Aristarchus Of Samos
Aristarchus of Samos (; , ; ) was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day. He also supported the theory of Anaxagoras according to which the Sun was just another star. He likely moved to Alexandria, and he was a student of Strato of Lampsacus, who later became the third head of the Peripatetic school in Greece. According to Ptolemy, he observed the summer solstice of 280 BC. Along with his contributions to the heliocentric model, as reported by Vitruvius, he created two separate sundials: one that is a flat disc; and one hemispherical. Aristarchus estimated the sizes of the Sun and Moon as compared to Earth's size. He also estimated the distances from the Earth to the Sun and Moon. His estimate that the Sun was 7 times larger than Earth (while inaccurate by an order of magnitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Greek Astronomy
Ancient Greek astronomy is the astronomy written in the Greek language during classical antiquity. Greek astronomy is understood to include the Ancient Greece, Ancient Greek, Hellenistic period, Hellenistic, Roman Empire, Greco-Roman, and Late antiquity, late antique eras. Ancient Greek astronomy can be divided into three phases, with ''Classical Greek astronomy'' being practiced during the 5th and 4th centuries BC, ''Hellenistic period, Hellenistic astronomy'' from the 3rd century BC until the formation of the Roman Empire in the late 1st century BC, and ''Greco-Roman astronomy'' continuing the tradition in the Roman world. During the Hellenistic era and onwards, Greek astronomy expanded beyond the geographic region of Greece as the Greek language had become the language of scholarship throughout the Hellenistic world, in large part delimited by the boundaries of the Macedonian Empire established by Alexander the Great. The most prominent and influential practitione ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Western Philosophy
Western philosophy refers to the Philosophy, philosophical thought, traditions and works of the Western world. Historically, the term refers to the philosophical thinking of Western culture, beginning with the ancient Greek philosophy of the Pre-Socratic philosophy, pre-Socratics. The word ''philosophy'' itself originated from the Ancient Greek (φιλοσοφία), literally, "the love of wisdom" , "to love" and σοφία ''Sophia (wisdom), sophía'', "wisdom". History Ancient The scope of ancient Western philosophy included the problems of philosophy as they are understood today; but it also included many other disciplines, such as pure mathematics and natural sciences such as physics, astronomy, and biology (Aristotle, for example, wrote on all of these topics). Pre-Socratics The pre-Socratic philosophers were interested in cosmology (the nature and origin of the universe), while rejecting unargued fables in place for argued theory, i.e., dogma superseded reason, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Āryabhaṭīya
''Aryabhatiya'' (IAST: ') or ''Aryabhatiyam'' ('), a Indian astronomy, Sanskrit astronomical treatise, is the ''Masterpiece, magnum opus'' and only known surviving work of the 5th century Indian mathematics, Indian mathematician Aryabhata. Philosopher of astronomy Roger Billard estimates that the book was composed around 510 CE based on historical references it mentions. Structure and style Aryabhatiya is written in Sanskrit and divided into four sections; it covers a total of 121 verses describing different moralitus via a mnemonic writing style typical for such works in India (see definitions below): # Gitikapada (13 verses): large units of time—Kalpa (aeon), kalpa, manvantara, and Yuga Cycle, yuga—which present a cosmology different from earlier texts such as Lagadha's Vedanga Jyotisha (ca. 1st century BCE). There is also a table of [sine]s (jya), given in a single verse. The duration of the planetary revolutions during a mahayuga is given as 4.32 million years, using the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Aryabhatta
Aryabhata ( ISO: ) or Aryabhata I (476–550 CE) was the first of the major mathematician-astronomers from the classical age of Indian mathematics and Indian astronomy. His works include the ''Āryabhaṭīya'' (which mentions that in 3600 '' Kali Yuga'', 499 CE, he was 23 years old) and the ''Arya- siddhanta''. For his explicit mention of the relativity of motion, he also qualifies as a major early physicist. Biography Name While there is a tendency to misspell his name as "Aryabhatta" by analogy with other names having the " bhatta" suffix, his name is properly spelled Aryabhata: every astronomical text spells his name thus, including Brahmagupta's references to him "in more than a hundred places by name". Furthermore, in most instances "Aryabhatta" would not fit the metre either. Time and place of birth Aryabhata mentions in the ''Aryabhatiya'' that he was 23 years old 3,600 years into the '' Kali Yuga'', but this is not to mean that the text was composed at that tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |