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Perseids
The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle that are usually visible from mid-July to late-August. The meteoroid, meteors are called the Perseids because they appear from the general direction of the constellation Perseus (constellation), Perseus and in more modern times have a radiant (meteor shower), radiant bordering on Cassiopeia (constellation), Cassiopeia and Camelopardalis. Etymology The name is derived from the word Perseids (mythology), Perseids (), the sons of Perseus in Greek mythology. Characteristics The stream of debris is called the Perseid cloud and stretches along the orbit of the comet Swift–Tuttle. The cloud consists of particles ejected by the comet as it travels on its 133-year orbit. Most of the particles have been part of the cloud for around a thousand years. However, there is also a relatively young filament of dust in the stream that was pulled off the comet in 1865, which can give an early mini-peak the da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perseus (constellation)
Perseus is a constellation in the Northern celestial hemisphere, northern sky, named after the Greek mythology, Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the IAU designated constellations, 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda (constellation), Andromeda to the west and Cassiopeia (constellation), Cassiopeia to the north. Perseus is also bordered by Aries (constellation), Aries and Taurus (constellation), Taurus to the south, Auriga (constellation), Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some Celestial cartography, star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose Asterism (astronomy), asterism was named together as ''Perseus et Capu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perseids (mythology)
In Greek mythology, the Perseids ( Perseid; , , ), also called the Perseid dynasty, the Perseid line, or the House of Perseus, are the descendants of Perseus and Andromeda (mythology), Andromeda. After the Greek Dark Ages, tradition recalled that Perseus and his descendants the Perseids had ruled Tiryns in Mycenaean Greece, Mycenaean times, while the allied branch descended from Perseus' great-uncle Proetus ruled in Argos, Peloponnese, Argos. Perseus and Andromeda had seven sons: Perses (son of Andromeda and Perseus), Perses, Alcaeus (mythology), Alcaeus, Heleus, Mestor, Sthenelus (son of Andromeda and Perseus), Sthenelus, Electryon, and Cynurus; and two daughters: Gorgophone, and Autochthe. Perses was left in Ethiopia (Mythology), Aethiopia and was believed to have become an ancestor of the Persian Empire, Persians. The other descendants ruled Mycenae from Electryon down to Eurystheus, after whom Atreus got the kingdom. The most renowned of the Perseids was the greatest Greek he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perseus
In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of monsters before the days of Heracles. He beheaded the Gorgon Medusa for Polydectes and saved Andromeda (mythology), Andromeda from the sea monster Cetus (mythology), Cetus. He was the son of Zeus and the mortal Danaë, as well as the half-brother and great-grandfather of Heracles (as they were both children of Zeus, and Heracles's mother was Perseus' granddaughter). Etymology Because of the obscurity of the name "Perseus" and the legendary character of its bearer, most etymologists presume that it might be pre-Greek; however, the name of Perseus's native city was Greek and so were the names of his wife and relatives. There is some idea that it descended into Greek from the Proto-Indo-European language. In that regard Robert Graves, Grave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface. Very intense or unusual meteor showers are known as meteor outbursts and meteor storms, which produce at least 1,000 meteors an hour, most notably from the Leonids. The Meteor Data Centre lists over 900 suspected meteor showers of which about 100 are well established. Several organizations point to viewing opportunities on the Internet. NASA maintains a daily map of active meteor showers. Historical developments A meteor shower in August 1583 was recorded in the Timbuktu manuscripts.Abraham, Curtis"Stars of the Sahara" ''New Scientist'', issue 2617,15 August 2007, page 39–41 I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Swift–Tuttle
Comet Swift–Tuttle (formally designated 109P/Swift–Tuttle) is a large periodic comet with a 1995 ( osculating) orbital period of 133 years that is in a 1:11 orbital resonance with Jupiter. It fits the classical definition of a Halley-type comet, which has an orbital period between 20 and 200 years. The comet was independently discovered by Lewis Swift on 16 July 1862 and by Horace Parnell Tuttle on 19 July 1862. Its nucleus is in diameter. Swift–Tuttle is the parent body of the Perseid meteor shower, perhaps the best known shower and among the most reliable in performance. The comet made a return appearance in 1992, when it was rediscovered by Japanese astronomer Tsuruhiko Kiuchi and became visible with binoculars. It was last observed in April 1995 when it was from the Sun. In 2126, it will be a bright naked-eye comet reaching an apparent magnitude of about 0.7. Historical observations Chinese records indicate that, in 188, the comet reached apparent magnitud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cassiopeia (constellation)
Cassiopeia () is a constellation and Asterism (astronomy), asterism in the northern sky named after the vain queen Cassiopeia (mother of Andromeda), Cassiopeia, mother of Andromeda (mythology), Andromeda, in Greek mythology, who boasted about her unrivaled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd-century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars. Cassiopeia is located in the northern sky and from latitudes above 34th parallel north, 34°N it is visible year-round. In the (sub)tropics it can be seen at its clearest from September to early November, and at low southern, tropical, latitudes of less than 25th parallel south, 25°S it can be seen, seasonally, low in the North. At magnitude 2.2, Alpha Cassiopeiae, or Schedar, is the brightest star in Cassiopeia. The constellation hosts some of the most luminous stars known, inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Swift–Tuttle
Comet Swift–Tuttle (formally designated 109P/Swift–Tuttle) is a large periodic comet with a 1995 ( osculating) orbital period of 133 years that is in a 1:11 orbital resonance with Jupiter. It fits the classical definition of a Halley-type comet, which has an orbital period between 20 and 200 years. The comet was independently discovered by Lewis Swift on 16 July 1862 and by Horace Parnell Tuttle on 19 July 1862. Its nucleus is in diameter. Swift–Tuttle is the parent body of the Perseid meteor shower, perhaps the best known shower and among the most reliable in performance. The comet made a return appearance in 1992, when it was rediscovered by Japanese astronomer Tsuruhiko Kiuchi and became visible with binoculars. It was last observed in April 1995 when it was from the Sun. In 2126, it will be a bright naked-eye comet reaching an apparent magnitude of about 0.7. Historical observations Chinese records indicate that, in 188, the comet reached apparent magnitud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
August
August is the eighth month of the year in the Julian and Gregorian calendars. Its length is 31 days. In the Southern Hemisphere, August is the seasonal equivalent of February in the Northern Hemisphere. In the Northern Hemisphere, August falls in summer. In the Southern Hemisphere, the month falls during winter. In many European countries, August is the holiday month for most workers. Numerous religious holidays occurred during August in ancient Rome. Certain meteor showers take place in August. The Kappa Cygnids occur in August, with yearly dates varying. The Alpha Capricornids meteor shower occurs as early as July 10 and ends around August 10. The Southern Delta Aquariids occur from mid-July to mid-August, with the peak usually around July 28–29. The Perseids, a major meteor shower, typically takes place between July 17 and August 24, with the peak days varying yearly. The star cluster of Messier 30 is best observed around August. Among the aborigines of the Canary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiant (meteor Shower)
The radiant or apparent radiant of a meteor shower is the celestial point in the sky from which (from the point of view of a terrestrial observer) the paths of meteors appear to originate. The Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. Meteor paths appear at random locations in the sky, but the apparent paths of two or more meteors from the same shower will diverge from the radiant. The radiant is the vanishing point of the meteor paths, which are parallel lines in three-dimensional space, as seen from the perspective of the observer, who views a two-dimensional projection against the sky. The geometric effect is identical to crepuscular rays, where parallel sunbeams appear to diverge. A meteor that does not point back to the known radiant for a given shower is known as a ''sporadic'' and is not considered part of that shower. Shower meteors may appear a short time before the radiant has risen in the observer's ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Desert
Sahara el Beyda, the White Desert Protected Area, is a national park in Egypt, first established as a protected area in 2002. It is located in the Farafra depression, north of the town of Qasr Al Farafra. Part of the park is in the Farafra Oasis (New Valley Governorate). The park is the site of large white chalk rock formations, created through erosion by wind and sand. It is also the site of cliffs (at the northern end of the Farafra Depression), sand dunes (part of the Great Sand Sea), as well as Wadi Hennis and oases at Ain El Maqfi and Ain El Wadi. White Desert National Park covers an area of . The highest point in the park is at El Qess Abu Said at above sea level, and the lowest is at Wadi Hennis at . The park serves as the refuge for various animals, including the endangered rhim gazelle and the vulnerable dorcas gazelle, as well as Barbary sheep; jackals; Rüppell's, red and fennec foxes; and the sand cat. In popular culture * In the Gathering Storm exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Units
The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. One au is approximately equivalent to 499 light-seconds. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical unit. In the astronomical literature, the symbol AU is common. In 2006, the International Bureau of Weights and Measures (BIPM) had recommended ua as the symbol for the unit, from the French "uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole. Due to Earth's axial tilt of 23.439281°, there is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags the variation in day and night. Conventionally, winter in the Northern Hemisphere is taken as the period from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer is taken as the period from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the Year#Astronomical years, astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that aff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
