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Draco (constellation)
Draco is a constellation in the far northern sky. Its name is Latin for dragon. It was one of the 48 Lists of constellations, constellations listed by the 2nd century Greek astronomer Ptolemy, and remains one of the 88 modern constellations today. The north pole of the ecliptic is in Draco. Draco is circumpolar star, circumpolar from northern latitudes, meaning that it never sets and can be seen at any time of year. Features Stars Thuban (α Draconis) was the northern pole star from 3942 BC, when it moved farther north than Theta Boötis, until 1793 BC. The Egyptian Pyramids were designed to have one side facing north, with an entrance passage geometrically aligned so that Thuban would be visible at night. Due to the effects of Axial precession (astronomy), precession, it will again be the pole star around the year AD 21000. It is a blue-white giant star of magnitude 3.7, 309 light-years from Earth. The traditional name of Alpha Draconis, Thuban, means "head of the serpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dragon
A dragon is a Magic (supernatural), magical legendary creature that appears in the folklore of multiple cultures worldwide. Beliefs about dragons vary considerably through regions, but European dragon, dragons in Western cultures since the High Middle Ages have often been depicted as winged, horned, and capable of breathing fire. Chinese dragon, Dragons in eastern cultures are usually depicted as wingless, four-legged, Snake, serpentine creatures with above-average intelligence. Commonalities between dragons' traits are often a hybridization of Reptile, reptilian, mammalian, and Bird, avian features. Etymology The word ''dragon'' entered the English language in the early 13th century from Old French , which, in turn, comes from Latin (genitive ), meaning "huge serpent, dragon", from , (genitive , ) "serpent". [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area around Rome, Italy. Through the expansion of the Roman Republic, it became the dominant language in the Italian Peninsula and subsequently throughout the Roman Empire. It has greatly influenced many languages, Latin influence in English, including English, having contributed List of Latin words with English derivatives, many words to the English lexicon, particularly after the Christianity in Anglo-Saxon England, Christianization of the Anglo-Saxons and the Norman Conquest. Latin Root (linguistics), roots appear frequently in the technical vocabulary used by fields such as theology, List of Latin and Greek words commonly used in systematic names, the sciences, List of medical roots, suffixes and prefixes, medicine, and List of Latin legal terms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aberration Of Starlight
In astronomy, aberration (also referred to as astronomical aberration, stellar aberration, or velocity aberration) is a phenomenon where celestial objects exhibit an apparent motion about their true positions based on the velocity of the observer: It causes objects to appear to be displaced towards the observer's direction of motion. The change in angle is of the order of where is the speed of light and the velocity of the observer. In the case of "stellar" or "annual" aberration, the apparent position of a star to an observer on Earth varies periodically over the course of a year as the Earth's velocity changes as it revolves around the Sun, by a maximum angle of approximately 20 arcseconds in right ascension or declination. The term ''aberration'' has historically been used to refer to a number of related phenomena concerning the propagation of light in moving bodies. Aberration is distinct from parallax, which is a change in the apparent position of a relatively ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axial Precession (astronomy)
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In particular, axial precession can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of approximately 26,000 years.Hohenkerk, C.Y., Yallop, B.D., Smith, C.A., & Sinclair, A.T. "Celestial Reference Systems" in Seidelmann, P.K. (ed.) ''Explanatory Supplement to the Astronomical Almanac''. Sausalito: University Science Books. p. 99. This is similar to the precession of a spinning top, with the axis tracing out a pair of cones joined at their apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis— nutation and polar motion—are much smaller in magnitude. Earth's precession was historically called the precession of the equinoxes, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egyptian Pyramids
The Egyptian pyramids are ancient masonry structures located in Egypt. Most were built as tombs for the pharaohs and their consorts during the Old Kingdom of Egypt, Old and Middle Kingdom of Egypt, Middle Kingdom periods. At least 138 identified pyramids have been discovered in Egypt. Approximately Nubian pyramids, 80 pyramids were built within the Kingdom of Kush, now located in the modern country of Sudan. The earliest known Egyptian pyramids are at Saqqara, west of Memphis, Egypt, Memphis. Step-pyramid-like structures, like Mastaba 3808 attributed to pharaoh Anedjib, may predate the Pyramid of Djoser built during the Third dynasty of Egypt, Third Dynasty. This pyramid and its surrounding complex are generally considered to be the world's oldest monumental structures constructed of ashlar, dressed masonry. The most famous Egyptian pyramids are those found at Giza Plateau, Giza, on the outskirts of Cairo, Egypt, Cairo. Several of the Giza pyramid complex, Giza pyrami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Boötis
Theta Boötis is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism. Its name is a Bayer designation that is Latinized from θ Boötis, and abbreviated Theta Boo or θ Boo. This star has the traditional name Asellus Primus, pronounced , which is Latin for "first donkey colt". Faintly visible to the naked eye, this star has a yellow-white hue with an apparent visual magnitude of 4.05. It is located at a distance of from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10.6 km/s. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.464 arc seconds per annum. Properties The stellar classification of Theta Boötis is F7 V, matching an F-type main-sequence star. It is a solar-type star that may be near the end of its main sequence lifetime based on a high luminosity for a star of its type. Theta Boötis is a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pole Star
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). From around 1700 BC until just after 300 AD, Kochab (Beta Ursae Minoris) and Pherkad (Gamma Ursae Minoris) were twin northern pole stars, though neither was as close to the pole as Polaris is now. History In classical antiquity, Beta Ursae Minoris (Kochab) was closer to the celestial north pole than Alpha Ursae Minoris. While there was no naked-eye star close to the pole, the midpoint between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thuban
Thuban (), with Bayer designation Alpha Draconis or α Draconis, is a binary star system in the northern constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star from the 4th to 2nd millennium BC. Johann Bayer gave Thuban the designation Alpha and placed it as the only member of his ''secundae'' magnitude class in Draco, although its current apparent magnitude of 3.65 means it is 3.7 times fainter than the brightest star in the constellation, Gamma Draconis (Eltanin), which Bayer placed in his ''tertiae'' magnitude class although its current apparent magnitude is 2.24. Nomenclature ''α Draconis'' ( Latinised to ''Alpha Draconis'') is the star's Bayer designation. The traditional name ''Thuban'' is derived from the Arabic word ' ('large snake' (e.g. a python or a legendary draconian serpent)). It is sometimes known as the ''Dragon's Tail'' and as ''Ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Star
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. Before the definition of the Arctic was formalized as the region north of the Arctic Circle which experiences the midnight sun, it more broadly meant those places where the 'bear' constellations (Ursa Major, the Great Bear, and Ursa Minor, the Little Bear) we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the fixed stars, background of stars – specifically the Zodiac constellations. The planets of the Solar System can also be seen along the ecliptic, because their orbital planes are very close to Earth's. The Moon's orbital plane is also similar to Earth's; the ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. The ecliptic is an important Plane of reference, reference plane and is the basis of the ecliptic coordinate system. Ancient scientists were able to calculate Earth's axial tilt by comparing the ecliptic plane to that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modern Constellations
In contemporary astronomy, 88 constellations are recognized by the International Astronomical Union (IAU). Each constellation is a region of the sky bordered by arcs of right ascension and declination, together covering the entire celestial sphere. Their boundaries were officially adopted by the International Astronomical Union in 1928 and published in 1930. The ancient Mesopotamians and later the Greeks established most of the northern constellations in international use today, listed by the Roman-Egyptian astronomer Ptolemy. The constellations along the ecliptic are called the zodiac. When explorers mapped the stars of the southern skies, European astronomers proposed new constellations for that region, as well as ones to fill gaps between the traditional constellations. Because of their Roman and European origins, every constellation has a Latin name. In 1922, the International Astronomical Union adopted three-letter abbreviations for 89 constellations, the modern list of 88 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
