Statue of Aristarchus at Aristoteles University in Thessaloniki, Greece

Aristarchus (310 BC - circa 230 BC) was a Greek astronomer and mathematician, born in Samos, Greece. He is the first recorded person to propose a heliocentric model of the solar system, placing the Sun, not the Earth, at the center of the known universe (hence he is sometimes known as the "Greek Copernicus"). His astronomical ideas were not well-received and were subordinated to those of Aristotle and Ptolemy, until they were successfully revived and developed by Copernicus nearly 2000 years later. Image File history File links Aristarchos_Samos. ... Image File history File links Aristarchos_Samos. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Centuries: 5th century BC - 4th century BC - 3rd century BC Decades: 360s BC 350s BC 340s BC 330s BC 320s BC 310s BC 300s BC 290s BC 280s BC 270s BC 260s BC Years: 315 BC 314 BC 313 BC 312 BC 311 BC _ 310 BC _ 309 BC... Centuries: 4th century BC - 3rd century BC - 2nd century BC Decades: 280s BC 270s BC 260s BC 250s BC 240s BC - 230s BC - 220s BC 210s BC 200s BC 190s BC 180s BC Years: 235 BC 234 BC 233 BC 232 BC 231 BC - 230 BC - 229 BC 228 BC... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... This article is in need of attention from an expert on the subject. ... Samos (Greek Σάμος; see also List of traditional Greek place names) is an island in southeastern Greece in the Aegean Sea, off the coast of Turkey. ... Heliocentric Solar System In astronomy, heliocentrism is the theory that the Sun is at the center of the Universe and/or the Solar System. ... Presentation of the solar system (not to scale) The solar system comprises our Sun and the retinue of celestial objects gravitationally bound to it. ... The Sun (or Sol) is the star at the center of our Solar system. ... Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. ... Nicolaus Copernicus (in Latin; Polish Mikołaj Kopernik, German Nikolaus Kopernikus - February 19, 1473 – May 24, 1543) was a Polish astronomer, mathematician and economist who developed a heliocentric (Sun-centered) theory of the solar system in a form detailed enough to make it scientifically useful. ... Aristotle, marble copy of bronze by Lysippos. ... Claudius Ptolemaeus, given contemporary German styling, in a 16th century engraved book frontispiece. ... Nicolaus Copernicus (in Latin; Polish Mikołaj Kopernik, German Nikolaus Kopernikus - February 19, 1473 – May 24, 1543) was a Polish astronomer, mathematician and economist who developed a heliocentric (Sun-centered) theory of the solar system in a form detailed enough to make it scientifically useful. ...

See also: Aristarchus, a bright crater on the Moon, and asteroid 3999 Aristarchus, both named after the astronomer. Aristarchus is a prominent lunar impact crater that lies in the northwest part of the Moons near side. ... This article is about impact craters, also known as meteor craters. ... Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... An asteroid is a small, solid object in our Solar System, orbiting the Sun. ... 3999 Aristarchus is a small main belt asteroid. ...

Heliocentrism

The only work of Aristarchus which has survived to the present time, On the Sizes and Distances of the Sun and Moon, is based on a geocentric worldview. We know through citations, however, that Aristarchus wrote another book in which he advanced an alternative hypothesis of the heliocentric model. Archimedes wrote: Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... A world view, also spelled as worldview is a term calqued from the German word Weltanschauung (look onto the world). The German word is also in wide use in English, as well as the translated form world outlook. ... A hypothesis (foundation from ancient Greek hupothesis where hupo = under and thesis = placing) is a proposed explanation for a phenomenon. ... Archimedes of Syracuse. ...

"You King Gelon are aware the 'universe' is the name given by most astronomers to the sphere the centre of which is the center of the Earth, while its radius is equal to the straight line between the center of the Sun and the center of the Earth. This is the common account as you have heard from astronomers. But Aristarchus has brought out a book consisting of certain hypotheses, wherein it appears, as a consequence of the assumptions made, that the universe is many times greater than the 'universe' just mentioned. His hypotheses are that the fixed stars and the Sun remain unmoved, that the Earth revolves about the Sun on the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of fixed stars, situated about the same center as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface."

Aristarchus thus believed the stars to be infinitely far away, and saw this as the reason why there was no visible parallax, that is, an observed movement of the stars relative to each other as the Earth moved around the Sun. The stars are in fact much farther away than was assumed in ancient times, which is why stellar parallax is only detectable with telescopes. But the geocentric model was assumed to be a simpler, better explanation for the lack of parallax. The rejection of the heliocentric view was apparently quite strong, as the following passage from Plutarch suggests (On the Apparent Face in the Orb of the Moon): The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of an observer. ... 50 cm refracting telescope at Nice Observatory. ... This drawing from an Icelandic manuscript dated around 1750 illustrates the geocentric model. ... Plutarch Mestrius Plutarchus (ca. ...

"[Cleanthes, a contemporary of Aristarchus] thought it was the duty of the Greeks to indict Aristarchus of Samos on the charge of impiety for putting in motion the Hearth of the universe [i.e. the earth], . . . supposing the heaven to remain at rest and the earth to revolve in an oblique circle, while it rotates, at the same time, about its own axis."

Size of the Moon

Main articles: Aristarchus On the Sizes and Distances, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

Aristarchus observed the Moon moving through the Earth's shadow during a lunar eclipse. He estimated that the diameter of the Earth was 3 times the Moon's diameter. Using Eratosthenes' calculation that the Earth was 42,000 km in circumference, he concluded that the Moon was 14,000 km in circumference. The Moon has a circumference of about 10,916 km. On the Sizes and Distances [of the Sun and Moon] is the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa 310 BC - 230 BC. In this work, he calculates the sizes of the Sun and Moon, as well as their distances from the... Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... An eclipse occurs whenever the Sun, Earth and Moon line up exactly. ... Eratosthenes (Ερατοσθένης) Eratosthenes (Ερατοσθένης) (276 BC - 194 BC) was a Greek mathematician, geographer and astronomer. ... The circumference is the distance around a closed curve. ...

Distance to the Sun

Main articles: Aristarchus On the Sizes and Distances, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

Aristarchus argued that the Sun, Moon, and Earth form a near right triangle at the moment of first or last quarter moon. He estimated that the angle was 87°. Using correct geometry, but inaccurate observational data, Aristarchus concluded that the Sun was 20 times farther away than the Moon. The true value of this angle is close to 89° 50', and the Sun is actually about 390 times farther away. He pointed out that the Moon and Sun have nearly equal apparent angular sizes and therefore their diameters must be in proportion to their distances from Earth. He thus concluded that the Sun was 20 times larger than the Moon. This is also incorrect, although logical. It does, however, suggest that the Sun is clearly larger than the Earth, which can be taken to support the heliocentric model. On the Sizes and Distances [of the Sun and Moon] is the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa 310 BC - 230 BC. In this work, he calculates the sizes of the Sun and Moon, as well as their distances from the... In astronomy, a phase of the Moon is any of the aspects or appearances presented by the Moon as seen from Earth, determined by the portion of the Moon that is visibly illuminated by the Sun. ... Geometry (Greek γεωμετρία; geo = earth, metria = measure) arose as the field of knowledge dealing with spatial relationships. ... This article is about angles in geometry. ...

External links

• Biography at the MacTutor archive
• Biography: JRASC, 75 (1981) 29

BITCH!111 ...

References

• Heath, Sir Thomas. Aristarchus of Samos - The Ancient Copernicus, A history of Greek astronomy to Aristarchus together with Aristarchus' treatise on the sizes and distances of the sun and moon, a new Greek text with translation and notes. (ISBN 0486438864)