Ancient Greece
Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 12th–9th centuries BC to the end of antiquity. Following this period was the beginning of the Early Middle Ages and the Byzantine era. Three centuries after the Late Bronze Age collapse of Mycenaean Greece, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and colonization of the Mediterranean Basin; this was followed by the period of Classical Greece, an era that began with the Greco-Persian Wars, lasting from the 5th to 4th centuries BC. Due to the conquests by Alexander the Great of Macedon, Hellenistic civilization flourished from Central Asia to the western end of the Mediterranean Sea; the Hellenistic period came to an end with the conquests and annexations of the eastern Mediterranean world by the Roman Republic, which established the Roman province of Macedonia in Roman Greece, the province of Achaea during the Roman Empire. Classical Greek culture philosophy, had a powerful influence on ancient Rome, which carried a version of it to many parts of the Mediterranean Basin and Europe.
For this reason, Classical Greece is considered to be the seminal culture which provided the foundation of modern Western culture and is considered the cradle of Western civilization. Classical Greek culture gave great importance to knowledge. Science and religion were not separate and getting closer to the truth meant getting closer to the gods. In this context, they understood the importance of mathematics as an instrument for obtaining more reliable knowledge. Greek culture, in a few centuries and with a limited population, managed to explore and make progress in many fields of science, mathematics and knowledge in general. Classical antiquity in the Mediterranean region is considered to have begun in the 8th century BC and ended in the 6th century AD. Classical antiquity in Greece was preceded by the Greek Dark Ages, archaeologically characterised by the protogeometric and geometric styles of designs on pottery. Following the Dark Ages was the Archaic Period, beginning around the 8th century BC.
The Archaic Period saw early developments in Greek culture and society which formed the basis for the Classical Period. After the Archaic Period, the Classical Period in Greece is conventionally considered to have lasted from the Persian invasion of Greece in 480 until the death of Alexander the Great in 323; the period is characterized by a style, considered by observers to be exemplary, i.e. "classical", as shown in the Parthenon, for instance. Politically, the Classical Period was dominated by Athens and the Delian League during the 5th century, but displaced by Spartan hegemony during the early 4th century BC, before power shifted to Thebes and the Boeotian League and to the League of Corinth led by Macedon; this period saw the Greco-Persian Wars and the Rise of Macedon. Following the Classical period was the Hellenistic period, during which Greek culture and power expanded into the Near and Middle East; this period ends with the Roman conquest. Roman Greece is considered to be the period between Roman victory over the Corinthians at the Battle of Corinth in 146 BC and the establishment of Byzantium by Constantine as the capital of the Roman Empire in AD 330.
Late Antiquity refers to the period of Christianization during the 4th to early 6th centuries AD, sometimes taken to be complete with the closure of the Academy of Athens by Justinian I in 529. The historical period of ancient Greece is unique in world history as the first period attested directly in proper historiography, while earlier ancient history or proto-history is known by much more circumstantial evidence, such as annals or king lists, pragmatic epigraphy. Herodotus is known as the "father of history": his Histories are eponymous of the entire field. Written between the 450s and 420s BC, Herodotus' work reaches about a century into the past, discussing 6th century historical figures such as Darius I of Persia, Cambyses II and Psamtik III, alluding to some 8th century ones such as Candaules. Herodotus was succeeded by authors such as Thucydides, Demosthenes and Aristotle. Most of these authors were either Athenian or pro-Athenian, why far more is known about the history and politics of Athens than those of many other cities.
Their scope is further limited by a focus on political and diplomatic history, ignoring economic and social history. In the 8th century BC, Greece began to emerge from the Dark Ages which followed the fall of the Mycenaean civilization. Literacy had been lost and Mycenaean script forgotten, but the Greeks adopted the Phoenician alphabet, modifying it to create the Greek alphabet. Objects with Phoenician writing on them may have been available in Greece from the 9th century BC, but the earliest evidence of Greek writing comes from graffiti on Greek pottery from the mid-8th century. Greece was divided into many small self-governing communities, a pattern dictated by Greek geography: every island and plain is cut off from its neighbors by the sea or mountain ranges; the Lelantine War is the earliest documented war of the ancient Greek period. It was fought between the important poleis of Chalcis and Eretria over the fertile Lelantine plain of Euboea. Both cities seem to have suffered a decline as result of the long war, though Chalcis was the nominal victor.
A mercantile class arose in the first half of the 7th century BC, shown by the introduction of coinage in about 680 BC. This
Labours of Hercules
The Twelve Labours of Heracles or Hercules are a series of episodes concerning a penance carried out by Heracles, the greatest of the Greek heroes, whose name was romanised as Hercules. They were accomplished over 12 years at the service of King Eurystheus; the episodes were connected by a continuous narrative. The establishment of a fixed cycle of twelve labours was attributed by the Greeks to an epic poem, now lost, written by Peisander, dated about 600 BC. After Hercules killed his wife and children, he went to the oracle at Delphi, he prayed to the god Apollo for guidance. Hercules was told to serve the king of Mycenae, for 12 years. During these 12 years, Hercules is sent to perform twelve difficult feats, called labours. Driven mad by Hera, Hercules slew his son and wife Megara. After recovering his sanity, Hercules regretted his actions. Pythia, the Oracle of Delphi, advised him to go to Tiryns and serve his cousin King Eurystheus for twelve years, performing whatever labors Eurystheus might set him.
Hercules despaired at this, loathing to serve a man whom he knew to be far inferior to himself, yet fearing to oppose his father Zeus. He placed himself at Eurystheus's disposal. Eurystheus ordered Hercules to perform ten labours. Hercules accomplished these tasks, but Eurystheus refused to recognize two: the slaying of the Lernaean Hydra, as Hercules' nephew and charioteer Iolaus had helped him. Eurystheus set two more tasks, which Hercules performed, bringing the total number of tasks to twelve; as they survive, the labours of Hercules are not recounted in any single place, but must be reassembled from many sources. Ruck and Staples assert that there is no one way to interpret the labours, but that six were located in the Peloponnese, culminating with the rededication of Olympia. Six others took the hero farther afield, to places that were, per Ruck, "all strongholds of Hera or the'Goddess' and were Entrances to the Netherworld". In each case, the pattern was the same: Hercules was sent to kill or subdue, or to fetch back for Eurystheus a magical animal or plant.
A famous depiction of the labours in Greek sculpture is found on the metopes of the Temple of Zeus at Olympia, which date to the 450s BC. In his labours, Hercules was sometimes accompanied by a male companion, according to Licymnius and others, such as Iolaus, his nephew. Although he was supposed to perform only ten labours, this assistance led to two labours being disqualified: Eurystheus refused to recognize slaying the Hydra, because Iolaus helped him, the cleansing of the Augean stables, because Hercules was paid for his services and because the rivers did the work. Several of the labours involved the offspring of Typhon and his mate Echidna, all overcome by Hercules. A traditional order of the labours found in the Bibliotheca is: Slay the Nemean lion. Slay the nine-headed Lernaean Hydra. Capture the Ceryneian Hind. Capture the Erymanthian Boar. Clean the Augean stables in a single day. Slay the Stymphalian birds. Capture the Cretan Bull. Steal the Mares of Diomedes. Obtain the girdle of Hippolyta.
Obtain the cattle of the monster Geryon. Steal the apples of the Hesperides. Capture and bring back Cerberus; the first labour was to slay the Nemean lion. According to one version of the myth, the Nemean lion took women as hostages to its lair in a cave near Nemea, luring warriors from nearby towns to save the damsel in distress. After entering the cave, the warrior would rush to her side. Once he was close, the woman would turn into a lion and kill the warrior, devouring his remains and giving the bones to Hades. Hercules wandered the area. There he met a boy who said that if Hercules slew the Nemean lion and returned alive within thirty days, the town would sacrifice a lion to Zeus, but if he did not return within thirty days or he died, the boy would sacrifice himself to Zeus. Another version claims that he met Molorchos, a shepherd who had lost his son to the lion, saying that if he came back within thirty days, a ram would be sacrificed to Zeus. If he did not return within thirty days, it would be sacrificed to the dead Hercules as a mourning offering.
While searching for the lion, Hercules fletched some arrows to use against it, not knowing that its golden fur was impenetrable. When he found and shot the lion, firing at it with his bow, he discovered the fur's protective property as the arrow bounced harmlessly off the creature's thigh. After some time, Hercules made the lion return to his cave; the cave had two entrances. In those dark and close quarters, Hercules stunned the beast with his club and, using his immense strength, strangled it to death. During the fight the lion bit off one of his fingers. Others say that he shot arrows at it shooting it in the unarmored mouth. After slaying the lion, he failed, he tried sharpening the knife with a stone and tried with the stone itself. Athena, noticing the hero's plight, told Hercules to use one of the lion's own claws to skin the pelt. Others say; when he returned on the thirtieth day carrying the carcass of the lion on his shoulders, King Eurystheus was amazed and terri
Leonids
The Leonids are a prolific meteor shower associated with the comet Tempel–Tuttle, which are known for their spectacular meteor storms that occur about every 33 years. The Leonids get their name from the location of their radiant in the constellation Leo: the meteors appear to radiate from that point in the sky, their proper Greek name should be Leontids, but the word was constructed as a Greek/Latin hybrid and it has been used since. They peak in the month of November. Earth moves through the meteoroid stream of particles left from the passages of a comet; the stream comprises solid particles, known as meteoroids, ejected by the comet as its frozen gases evaporate under the heat of the Sun when it is close enough – closer than Jupiter's orbit. The Leonids are a fast moving stream which encounter the path of impact at 72 km/s. Larger Leonids which are about 10 mm across have a mass of half a gram and are known for generating bright meteors. An annual Leonid shower may deposit 13 tons of particles across the entire planet.
The meteoroids left by the comet are organized in trails in orbits similar to though different from that of the comet. They are differentially disturbed by the planets, in particular Jupiter and to a lesser extent by radiation pressure from the sun, the Poynting–Robertson effect, the Yarkovsky effect; these trails of meteoroids cause meteor showers. Old trails are spatially not compose the meteor shower with a few meteors per minute. In the case of the Leonids, that tends to peak around November 18, but some are spread through several days on either side and the specific peak changes every year. Conversely, young trails are spatially dense and the cause of meteor outbursts when the Earth enters one; the Leonids produce meteor storms about every 33 years, which exceed 1,000 meteors per hour, in contrast to the sporadic background and the shower background. The Leonids are famous because storms, can be among the most spectacular; because of the storm of 1833 and the recent developments in scientific thought of the time, the Leonids have had a major effect on the development of the scientific study of meteors, thought to be atmospheric phenomena.
Although it has been suggested the Leonid meteor shower and storms have been noted in ancient times, it was the meteor storm of 1833 that broke into people's modern day awareness – it was of superlative strength. One estimate of the peak rate is over one hundred thousand meteors an hour, but another, done as the storm abated, estimated in excess of 240,000 meteors during the nine hours of the storm, over the entire region of North America east of the Rocky Mountains, it was marked by several nations of Native Americans: the Cheyenne established a peace treaty and the Lakota calendar was reset. Abolitionists including Harriet Tubman and Frederick Douglass as well as slave-owners took note and others; the New York Evening Post carried a series of articles on the event including reports from Canada to Jamaica, it made news in several states beyond New York and though it appeared in North America was talked about in Europe. The journalism of the event tended to rise above the partisan debates of the time and reviewed facts as they could be sought out.
Abraham Lincoln commented on it years later. Near Independence, Missouri, in Clay County, a refugee Mormon community watched the meteor shower on the banks of the Missouri River after having been driven from their homes by local settlers; the founder and first leader of Mormonism, Joseph Smith, afterwards noted in his journal his belief that this event was a literal fulfillment of the word of God and a sure sign that the coming of Christ was close at hand. Though it was noted in the midwest and eastern areas it was noted in the far west. Denison Olmsted explained the event most accurately. After spending the last weeks of 1833 collecting information, he presented his findings in January 1834 to the American Journal of Science and Arts, published in January–April 1834, January 1836, he noted the shower was of short duration and was not seen in Europe, that the meteors radiated from a point in the constellation of Leo and he speculated the meteors had originated from a cloud of particles in space.
Accounts of the 1866 repeat of the Leonids counted hundreds per minute/a few thousand per hr in Europe. The Leonids were again seen in 1867. Another strong appearance of the Leonids in 1868 reached an intensity of 1000 per hour in dark skies, it was in 1866–67 that information on Comet Tempel-Tuttle was gathered pointing it out as the source of the meteor shower. When the storms failed to return in 1899, it was thought that the dust had moved on and storms were a thing of the past. In 1966, a spectacular storm was seen over the Americas. Historical notes were gathered thus noting the Leonids back to 900AD. Radar studies showed the 1966 storm included a high percentage of smaller particles while 1965's lower activity had a much higher proportion of larger particles. In 1981 Donald K. Yeomans of the Jet Propulsion Laboratory reviewed the history of meteor showers for the Leonids and the history of the dynamic orbit of Comet Tempel-Tuttle. A graph from it was re-published in Sky and Telescope, it showed relative positions of the Earth and Tempel-Tuttle and marks where Earth encountered dense dust.
This showed that the meteoroids are behind and outside the path of the comet, but paths of the Earth through the cloud of particles resulting in powerful storms were nea
Nemean lion
The Nemean lion was a vicious monster in Greek mythology that lived at Nemea. It was killed by Heracles, it could not be killed with mortals' weapons. Its claws could cut through any armor. Today, lions are not part of the Greek fauna; the Asiatic lion subspecies ranged in southeastern Europe. According to Herodotus, lion populations were extant in Ancient Greece, until around 100 BC when they became extinct; the lion is considered to have been the offspring of Typhon and Echidna. The Nemean lion was sent to Nemea in the Peloponnesus to terrorize the city; the first of Heracles' twelve labours, set by King Eurystheus, was to slay the Nemean lion. Heracles wandered the area. There he met a boy who said that if Heracles slew the Nemean lion and returned alive within 30 days, the town would sacrifice a lion to Zeus. Another version claims that he met Molorchos, a shepherd who had lost his son to the lion, saying that if he came back within 30 days, a ram would be sacrificed to Zeus. If he did not return within 30 days, it would be sacrificed to the dead Heracles as a mourning offering.
While searching for the lion, Heracles fetched some arrows to use against it, not knowing that its golden fur was impenetrable. After some time, Heracles made the lion return to his cave; the cave had two entrances. In those dark and close quarters, Heracles stunned the beast with his club. During the fight the lion bit off one of his fingers, he killed the lion by strangling it with his bare hands. After slaying the lion, he failed, he tried sharpening the knife with a stone and tried with the stone itself. Athena, noticing the hero's plight, told Heracles to use one of the lion's own claws to skin the pelt; when he returned on the thirtieth day carrying the carcass of the lion on his shoulders, King Eurystheus was amazed and terrified. Eurystheus forbade him again to enter the city. Eurystheus warned him that the tasks set for him would become difficult, he sent Heracles off to complete his next quest, to destroy the Lernaean hydra. Heracles wore the Nemean lion's coat after killing it, as it was impervious to the elements and all but the most powerful weapons.
Others say. According to some authors, Heracles was helped in this labour by an Earth-born serpent, which followed him to Thebes and settled down in Aulis, it was identified as the water snake which devoured the sparrows and was turned into stone in the prophecy about the Trojan War. Smith, William. "Heracles or Hercules" Media related to Nemean Lion at Wikimedia Commons
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 high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so all of them disintegrate and never hit the Earth's surface. 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; the first great meteor storm in the modern era was the Leonids of November 1833. One estimate is a peak rate of over one hundred thousand meteors an hour, but another, done as the storm abated, estimated in excess of two hundred thousand meteors during the 9 hours of storm, over the entire region of North America east of the Rocky Mountains.
American Denison Olmsted explained the event most accurately. After spending the last weeks of 1833 collecting information, he presented his findings in January 1834 to the American Journal of Science and Arts, published in January–April 1834, January 1836, he noted the shower was of short duration and was not seen in Europe, that the meteors radiated from a point in the constellation of Leo and he speculated the meteors had originated from a cloud of particles in space. Work continued, yet coming to understand the annual nature of showers though the occurrences of storms perplexed researchers; the actual nature of meteors was still debated during the XIX century. Meteors were conceived as an atmospheric phenomenon by many scientists until the Italian astronomer Giovanni Schiaparelli ascertained the relation between meteors and comets in his work "Notes upon the astronomical theory of the falling stars". In the 1890s, Irish astronomer George Johnstone Stoney and British astronomer Arthur Matthew Weld Downing, were the first to attempt to calculate the position of the dust at Earth's orbit.
They studied the dust ejected in 1866 by comet 55P/Tempel-Tuttle in advance of the anticipated Leonid shower return of 1898 and 1899. Meteor storms were anticipated, but the final calculations showed that most of the dust would be far inside of Earth's orbit; the same results were independently arrived at by Adolf Berberich of the Königliches Astronomisches Rechen Institut in Berlin, Germany. Although the absence of meteor storms that season confirmed the calculations, the advance of much better computing tools was needed to arrive at reliable predictions. In 1981 Donald K. Yeomans of the Jet Propulsion Laboratory reviewed the history of meteor showers for the Leonids and the history of the dynamic orbit of Comet Tempel-Tuttle. A graph from it was re-published in Sky and Telescope, it showed relative positions of the Earth and Tempel-Tuttle and marks where Earth encountered dense dust. This showed that the meteoroids are behind and outside the path of the comet, but paths of the Earth through the cloud of particles resulting in powerful storms were near paths of nearly no activity.
In 1985, E. D. Kondrat'eva and E. A. Reznikov of Kazan State University first identified the years when dust was released, responsible for several past Leonid meteor storms. In 1995, Peter Jenniskens predicted the 1995 Alpha Monocerotids outburst from dust trails. In anticipation of the 1999 Leonid storm, Robert H. McNaught, David Asher, Finland's Esko Lyytinen were the first to apply this method in the West. In 2006 Jenniskens published predictions for future dust trail encounters covering the next 50 years. Jérémie Vaubaillon continues to update predictions based on observations each year for the Institut de Mécanique Céleste et de Calcul des Éphémérides; because meteor shower particles are all traveling in parallel paths, at the same velocity, they will all appear to an observer below to radiate away from a single point in the sky. This radiant point is caused by the effect of perspective, similar to parallel railroad tracks converging at a single vanishing point on the horizon when viewed from the middle of the tracks.
Meteor showers are always named after the constellation from which the meteors appear to originate. This "fixed point" moves across the sky during the night due to the Earth turning on its axis, the same reason the stars appear to march across the sky; the radiant moves from night to night against the background stars due to the Earth moving in its orbit around the sun. See IMO Meteor Shower Calendar 2017 for maps of drifting "fixed points." When the moving radiant is at the highest point it will reach in the observer's sky that night, the sun will be just clearing the eastern horizon. For this reason, the best viewing time for a meteor shower is slightly before dawn — a compromise between the maximum number of meteors available for viewing, the lightening sky which makes them harder to see. Meteor showers are named after the nearest constellation or bright star with a Greek or Roman letter assigned, close to the radiant position at the peak of the shower, whereby the grammatical declension of the Latin possessive form is replaced by "id" or "ids".
Hence, meteors radiating from near the star delta Aquarii are called delta Aquariids. The International Astronomical Union's Task Group on Meteor Shower Nomenclature and the IAU's Meteor Data Center keep track of meteor shower nomenclature and which showers are e
Double star
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth with the aid of optical telescopes. This occurs because the pair either forms a binary star or is an optical double, a chance line-of-sight alignment of two stars at different distances from the observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. Since the beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles between double stars to determine the relative motions of the pairs. If the relative motion of a pair determines a curved arc of an orbit, or if the relative motion is small compared to the common proper motion of both stars, it may be concluded that the pair is in mutual orbit as a binary star. Otherwise, the pair is optical. Multiple stars are studied in this way, although the dynamics of multiple stellar systems are more complex than those of binary stars.
The following are three types of paired stars: Optical doubles are unrelated stars that appear close together through chance alignment with Earth. Visual binaries are gravitationally-bound stars. Non-visual binaries are stars whose binary status was deduced through more esoteric means, such as occultation, spectroscopy, or anomalies in proper motion. Improvements in telescopes can shift non-visual binaries into visual binaries, as happened with Polaris A in 2006, it is only the inability to telescopically observe two separate stars that distinguish non-visual and visual binaries. Mizar, in Ursa Major, was observed to be double by Benedetto Galileo; the identification of other doubles soon followed: Robert Hooke discovered one of the first double-star systems, Gamma Arietis, in 1664, while the bright southern star Acrux, in the Southern Cross, was discovered to be double by Fontenay in 1685. Since that time, the search has been carried out and the entire sky has been examined for double stars down to a limiting apparent magnitude of about 9.0.
At least 1 in 18 stars brighter than 9.0 magnitude in the northern half of the sky are known to be double stars visible with a 36-inch telescope. The unrelated categories of optical doubles and true binaries are lumped together for historical and practical reasons; when Mizar was found to be a binary, it was quite difficult to determine whether a double star was a binary system or only an optical double. Improved telescopes and photography are the basic tools used to make the distinction. After it was determined to be a visual binary, Mizar's components were found to be spectroscopic binaries themselves. Observation of visual double stars by visual measurement will yield the separation, or angular distance, between the two component stars in the sky and the position angle; the position angle specifies the direction in which the stars are separated and is defined as the bearing from the brighter component to the fainter, where north is 0°. These measurements are called measures. In the measures of a visual binary, the position angle will change progressively and the separation between the two stars will oscillate between maximum and minimum values.
Plotting the measures in the plane will produce an ellipse. This is the projection of the orbit of the two stars onto the celestial sphere. Although it is expected that the majority of catalogued visual doubles are visual binaries, orbits have been computed for only a few thousand of the over 100,000 known visual double stars. Confirmation of a visual double star as a binary star can be achieved by observing the relative motion of the components. If the motion is part of an orbit, or if the stars have similar radial velocities or the difference in their proper motions is small compared to their common proper motion, the pair is physical; when observed over a short period of time, the components of both optical doubles and long-period visual binaries will appear to be moving in straight lines. Some bright visual double stars have a Bayer designation. In this case, the components may be denoted by superscripts. An example of this is α Crucis, whose components are α2 Crucis. Since α1 Crucis is a spectroscopic binary, this is a multiple star.
Superscripts are used to distinguish more distant, physically unrelated, pairs of stars with the same Bayer designation, such as α1,2 Capricorni, ξ1,2 Centauri, ξ1,2 Sagittarii. These optical pairs are resolvable by the naked eye. Apart from these pairs, the components of a double star are denoted by the letters A and B appended to the designation, of whatever sort, of the double star. For example, the components of α Canis Majoris are α Canis Majoris A and α Canis Majoris B; the letters AB may be used together to designate the pair. In the case of multiple stars, the letters C, D, so on may be used to denote additional components in order of increasing separation from the brightest star, A. Visual doubles are designated by an abbreviation for the name of their discoverer followed by a catalogue number unique to that observer. For example, the pair α Centauri AB was discovered by Father Ri
(Unicode ♌). One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Leo remains one of the 88 modern constellations today, and one of the most easily recognizable due to its many bright stars and a distinctive shape that is reminiscent of the crouching lion it depicts; the lion's mane and shoulders also form an asterism known as "The Sickle," which to modern observers may resemble a backwards "question mark."
Media related to Leo (constellation) at Wikimedia Commons
