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The Project Gutenberg EBook of History of Astronomy, by George
The Project Gutenberg EBook of History of Astronomy, by George

... An attempt has been made in these pages to trace the evolution of intellectual thought in the progress of astronomical discovery, and, by recognising the different points of view of the different ages, to give due credit even to the ancients. No one can expect, in a history of astronomy of limited s ...
History of Astronomy
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... moon, and later the planets, were seen to crawl over it. It was a great step to look on the vault as a hollow sphere carrying the sun too. It must have been difficult to believe that at midday the stars are shining as brightly in the blue sky as they do at night. It must have been difficult to expla ...
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... background which is actually due to the Earth’s orbit around the Sun – the further away the star, the smaller the circle. This means that at some distance this circle will appear to be a point and the parallax would be impossible to measure. For stars which are more than a few thousand light-years a ...
Transit detecion on eclipsing binary systems
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... statistics C is obtained from a scalar multiplication of the vectors representing model-lc and observed data. Jenkins et al. present this TDA in the context of the transit detection of EBs TEP project (1994-2000; Deeg et al 1998,Doyle et al 2000.) detection statistics is obtained from a comparison o ...
9. Asteroids, Comets, and Dwarf Planets
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... the governing council consisting of 20 advisors to the King. In 1559 Tycho began his studies at the University of Copenhagen. There, following the wishes of his uncle, he studied law but also studied a variety of other subjects and became interested in astronomy. In 1562 he set off to go to the Univ ...
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... that the laws that govern motions on Earth and in the heavens are the same Up to 5 points. In particular, he showed that the acceleration that pulls an apple to the ground, is due to the same force of gravity that keeps the Moon “falling” in its orbit around the Earth. (4 points). Up to 5 more point ...
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... Dwarfs) and continue to be found at distances less than 5 pc (Henry et al. 1997; Jao et al. 2005; Henry et al. 2006). These objects span a huge range in brightness (9 < Mv < 20), have masses between 0.50.6 and 0.08 Msun (Henry et al. 2004, Delfosse et al. 2000), and have been assigned spectral type ...
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... perfect eastern viewpoint and make your camera and tripod ready. Venus at magnitude -4 is the easiest planet to locate about 20° above the eastern horizon in the dim constellation Pisces. If you look at the planet in a telescope, you’ll find that it is almost completely illuminated (90%) and a littl ...
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... (All you need to know about Gas Giants to survive the day) A gas giant is a large planet that is mostly made of gas (or gas compressed into a liquid). Unlike rocky planets, gas giants do not have a well-defined surface. There are four gas giants in our solar system: Jupiter, Saturn, Uranus, and Nept ...
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... Shrinkage of White Dwarfs • Quantum mechanics says that electrons in the same place cannot be in the same state • Adding mass to a white dwarf increases its gravity, forcing electrons into a smaller space • In order to avoid being in the same state in the same place some of the electrons need to mo ...
ph507weeks1
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... parallax accuracy to 0.001” within a few years. Before 1990, fewer than 10,000 stellar parallaxes had been measured (and only 500 known well), but there are about 1012 stars in our Galaxy. Space observations made by the European Space Agency with the Hipparcos mission (1989-1993) accurately determin ...
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Definition of planet



The definition of planet, since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies. Greek astronomers employed the term asteres planetai (ἀστέρες πλανῆται), ""wandering stars"", for star-like objects which apparently moved over the sky. Over the millennia, the term has included a variety of different objects, from the Sun and the Moon to satellites and asteroids.By the end of the 19th century the word planet, though it had yet to be defined, had become a working term applied only to a small set of objects in the Solar System. After 1992, however, astronomers began to discover many additional objects beyond the orbit of Neptune, as well as hundreds of objects orbiting other stars. These discoveries not only increased the number of potential planets, but also expanded their variety and peculiarity. Some were nearly large enough to be stars, while others were smaller than Earth's moon. These discoveries challenged long-perceived notions of what a planet could be.The issue of a clear definition for planet came to a head in 2005 with the discovery of the trans-Neptunian object Eris, a body more massive than the smallest then-accepted planet, Pluto. In its 2006 response, the International Astronomical Union (IAU), recognised by astronomers as the world body responsible for resolving issues of nomenclature, released its decision on the matter. This definition, which applies only to the Solar System, states that a planet is a body that orbits the Sun, is massive enough for its own gravity to make it round, and has ""cleared its neighbourhood"" of smaller objects around its orbit. Under this new definition, Pluto and the other trans-Neptunian objects do not qualify as planets. The IAU's decision has not resolved all controversies, and while many scientists have accepted the definition, some in the astronomical community have rejected it outright.
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