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March Equinox
The March equinox or northward equinox is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the vernal equinox (or spring equinox) in the Northern Hemisphere and as the autumnal equinox (or fall equinox) in the Southern Hemisphere. On the Gregorian calendar at 0° longitude, the northward equinox can occur as early as 19 March (which happened most recently in 1796, and will happen next in 2044), and it can occur as late as 21 March (which happened most recently in 2007, and will happen next in 2102). For a common year the computed time slippage is about 5 hours 49 minutes ''later'' than the previous year, and for a leap year about 18 hours 11 minutes ''earlier'' than the previous year. Balancing the increases of the common years against the losses of the leap years keeps the calendar date of the March equinox from drifting more than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summer
Summer or summertime is the hottest and brightest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, daylight hours are the longest and darkness hours are the shortest, with day length decreasing as the season progresses after the solstice. The earliest sunrises and latest sunsets also occur near the date of the solstice. The date of the beginning of summer varies according to definition, climate, tradition, and culture. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, and vice versa. Etymology The modern English ''summer'' derives from the Middle English ''somer'', via the Old English ''sumor''. Timing From an astronomical view, the equinoxes and solstices would be the middle of the respective seasons, but sometimes astronomical summer is defined as starting at the solstice, the time of maximal insolation, often identified with 21 June or 21 December. By solar reckonin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capricornus
Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat Horn (anatomy), horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is half goat, half fish. Capricornus is one of the 88 modern constellations, and was also one of the 48 constellations listed by the 2nd century astronomer Ptolemy, Claudius Ptolemy. Its old astronomical symbol is (♑︎). Under its modern boundaries it is bordered by Aquila (constellation), Aquila, Sagittarius (constellation), Sagittarius, Microscopium, Piscis Austrinus, and Aquarius (constellation), Aquarius. The constellation is located in an area of sky called the Sea (astronomy), Sea or the Water, consisting of many water-related constellations such as Aquarius, Pisces (constellation), Pisces and Eridanus (constellation), Eridanus. It is the smallest constellation in the zodiac. Notable features Stars Capricornus is a faint ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taurus (constellation)
Taurus (Latin, 'Bull') is one of the constellations of the zodiac and is located in the northern celestial hemisphere. Taurus is a large and prominent constellation in the Northern Hemisphere's winter sky. It is one of the oldest constellations, dating back to the Early Bronze Age at least, when it marked the location of the Sun during the spring equinox. Its importance to the agricultural calendar influenced sacred bull, various bull figures in the mythologies of Ancient Sumerian religion, Sumer, Akkadian religion, Akkad, Assyrian religion, Assyria, Babylonian religion, Babylon, Ancient Egyptian religion, Egypt, Ancient Greek religion, Greece, and Religion in ancient Rome, Rome. Its old astronomical symbol is (♉︎), which resembles a bull's head. A number of features exist that are of interest to astronomers. Taurus hosts two of the nearest open clusters to Earth, the Pleiades and the Hyades (star cluster), Hyades, both of which are visible to the naked eye. At first magnitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
88 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 Greek astronomy, 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 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquarius (constellation)
Aquarius is an celestial equator, equatorial constellation of the zodiac, between Capricornus and Pisces (constellation), Pisces. Its name is Latin for "water-carrier" or "cup-carrier", and its old astronomical symbol is (♒︎), a representation of water. Aquarius is one of the oldest of the recognized constellations along the zodiac (the Sun's apparent path). It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the IAU designated constellations, 88 modern constellations. It is found in a region often called the Sea (astronomy), Sea due to its profusion of constellations with watery associations such as Cetus the whale, Pisces the fish, and Eridanus (constellation), Eridanus the river. At apparent magnitude 2.9, Beta Aquarii is the brightest star in the constellation. History and mythology Aquarius is identified as "The Great One" in the Babylonian star catalogues and represents the god Ea (god), Ea himself, who is commonl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pisces (constellation)
Pisces is a constellation of the zodiac. Its vast bulk – and main asterism viewed in most European cultures per Greco-Roman antiquity as a distant pair of fishes connected by one cord each that join at an apex – are in the Northern celestial hemisphere. Its old astronomical symbol is (♓︎). Its name is Latin for "fishes". It is between Aquarius (constellation), Aquarius, of similar size, to the southwest and Aries (constellation), Aries, which is smaller, to the east. The ecliptic and the celestial equator intersect within this constellation and in Virgo (constellation), Virgo. The Sun subsolar point, passes directly overhead of the equator, on average, at approximately this point in the sky, at the March equinox. The right ascension/declination 00 is located within the boundaries of Pisces. Features The March equinox is currently located in Pisces, due south of Psc, and, due to precession, slowly drifting due west, just below the western fish towards Aquari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aries (constellation)
Aries is one of the constellations of the zodiac. It is located in the Northern celestial hemisphere between Pisces (constellation), Pisces to the west and Taurus (constellation), Taurus to the east. The name Aries is Latin for sheep, ram. Its traditional astrological symbol is (♈︎). It is one of the 48 constellations described by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. It is a mid-sized constellation ranking 39th in overall size, with an area of 441 square degrees (1.1% of the celestial sphere). Aries has represented a ram since late Babylonian times. Before that, the stars of Aries formed a farmhand. Different cultures have incorporated the stars of Aries into different constellations including twin inspectors in China and a porpoise in the Marshall Islands. Aries is a relatively dim constellation, possessing only four bright stars: Hamal (Alpha Arietis, second magnitude), Sheratan (Beta Arietis, third magnitude), Mesarthim ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellations were likely defined in prehistory. People used them to relate stories of their beliefs, experiences, creation myth, creation, and mythology. Different cultures and countries invented their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, only to drop into obscurity. Some were limited to a single culture or nation. Naming constellations also helped astronomers and navigators identify stars more easily. Twelve (or thirteen) ancient constellations belong to the zodiac (straddling the ecliptic, which the Sun, Moon, and planets all traver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precession Of The Equinoxes
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's Rotation around a fixed axis, 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 Cone (geometry), cones joined at their Apex (geometry), apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis—astronomical nutation, nutation and polar motion—are much smaller in magnitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic Coordinate System
In astronomy, the ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bodies have orbits with only slight inclinations to the ecliptic, using it as the fundamental plane is convenient. The system's origin can be the center of either the Sun or Earth, its primary direction is towards the March equinox, and it has a right-hand convention. It may be implemented in spherical or rectangular coordinates. Primary direction The celestial equator and the ecliptic are slowly moving due to perturbing forces on the Earth, therefore the orientation of the primary direction, their intersection at the March equinox, is not quite fixed. A slow motion of Earth's axis, precession, causes a slow, continuous turning of the coordinate system westward about the poles of the ecliptic, completing one circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
