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Eridanus (constellation)
Eridanus is a constellation which stretches along the southern celestial hemisphere. It is represented as a river. One of the 48 constellations listed by the 2nd century AD astronomer Ptolemy, it remains one of the 88 modern constellations. It is the List of constellations by area, sixth largest of the modern constellations. The same name was later taken as a Latin name for the real Po River and also for the name of a Eridanos (Athens), minor river in Athens. Features Stars At its southern end is the apparent magnitude, magnitude 0.5 star Achernar, designated Alpha Eridani. It is a blue-white hued main sequence star 144 light-years from Earth, whose traditional name means "the river's end". Achernar is a very peculiar star because it is one of the flattest stars known. Observations indicate that its radius is about 50% larger at the equator than at the poles. This distortion occurs because the star is spinning extremely rapidly. There are several other noteworthy stars in E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanos (river Of Hades)
The river Eridanos or Eridanus (; ) is, both, the name of a river in Northern Europe mentioned in Greek mythology and historiography, and the name of the god of said river. Mythical stream Hesiod, in the '' Theogony,'' calls it "deep-eddying Eridanos" in his list of rivers, the offspring of the Titans Tethys and her brother-husband Oceanus. He was called the king of the rivers. Herodotus suspects the word ''Eridanos'' to be essentially Greek in character, and notably forged by some unknown poet, and expresses his disbelief in the whole concept—passed on to him by others, themselves not eye-witnesses—of such a river flowing into a northern sea, surrounding Europe, where the mythical Amber and Tin Isles were supposed; he upholds the belief in the abundance of natural goods at the world's ends though, to be found in the north of Europe as well as in India (east: big animals, gold, cotton) and Arabia (south: incense, myrrh, etc.). The Eridanos was later associated with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Celestial Hemisphere
The southern celestial hemisphere, also called the Southern Sky, is the Southern Hemisphere, southern half of the celestial sphere; that is, it lies south of the celestial equator. This arbitrary sphere, on which seemingly fixed stars form constellations, diurnal motion, appears to rotate westward around a celestial pole, polar axis as the Earth Earth's rotation, rotates. At all times, the entire Southern Sky is visible from the geographic South Pole; less of the Southern Sky is visible the latitude, further north the observer is located. The northern counterpart is the northern celestial hemisphere. Astronomy In the context of astronomical discussions or writing about celestial cartography, celestial mapping, it may also simply then be referred to as the Southern Hemisphere. For the purpose of celestial mapping, the sky is considered by Astronomer, astronomers as the inside of a sphere divided in two halves by the celestial equator. The Southern Sky or Southern Hemisphere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Eridani
Beta Eridani (β Eridani, abbreviated Beta Eri, β Eri), formally named Cursa , is the second-brightest star in the constellation of Eridanus, located in the northeast end of this constellation near the shared border with Orion. The apparent visual magnitude of this star is 2.796, so it can be viewed with the naked eye in dark skies. Parallax measurements yield an estimated distance of about from the Earth. Nomenclature ''Beta Eridani'' is the star's Bayer designation. It has the traditional name ''Cursa'' derived from ', "the Chair (or "Footstool") of the Central One". This is the name of the star association consisting of this star along with Lambda Eridani, Psi Eridani and Tau Orionis. According to a NASA catalogue of stars, ' was the title of three stars: β Eri is ''Cursa'', Psi Eridani ', and Lambda Eridani ' (excluding Tau Orionis). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or dwarf stars, and positions of stars on and off the band are believed to indicate their physical properties, as well as their progress through several types of star life-cycles. These are the most numerous true stars in the universe and include the Sun. Color-magnitude plots are known as Hertzsprung–Russell diagrams after Ejnar Hertzsprung and Henry Norris Russell. After condensation and ignition of a star, it generates thermal energy in its dense stellar core, core region through nuclear fusion of hydrogen into helium. During this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass but also based on its chemical composition and age. The cores of main-sequence stars are in hydros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night; their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and traces of heavier elements. Its stellar mass, total mass mainly determines it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), extinction of the object's light caused by interstellar dust along the sightline, line of sight to the observer. Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient Ancient Greek astronomy#Astronomy in the Greco-Roman and Late Antique eras, Roman astronomer Ptolemy, Claudius Ptolemy, whose Star catalogue, star catalog popularized the system by listing stars from First-magnitude star, 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined to closely match this historical system by Norman Robert Pogson, Norman Pogson in 1856. The scale is reverse logarithmic scale, logarithmic: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation Eridanus
Eridanus is a constellation which stretches along the southern celestial hemisphere. It is represented as a river. One of the 48 constellations listed by the 2nd century AD astronomer Ptolemy, it remains one of the 88 modern constellations. It is the sixth largest of the modern constellations. The same name was later taken as a Latin name for the real Po River and also for the name of a minor river in Athens. Features Stars At its southern end is the magnitude 0.5 star Achernar, designated Alpha Eridani. It is a blue-white hued main sequence star 144 light-years from Earth, whose traditional name means "the river's end". Achernar is a very peculiar star because it is one of the flattest stars known. Observations indicate that its radius is about 50% larger at the equator than at the poles. This distortion occurs because the star is spinning extremely rapidly. There are several other noteworthy stars in Eridanus, including some double stars. Beta Eridani, traditionally ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athens
Athens ( ) is the Capital city, capital and List of cities and towns in Greece, largest city of Greece. A significant coastal urban area in the Mediterranean, Athens is also the capital of the Attica (region), Attica region and is the southernmost capital on the European mainland. With its urban area's population numbering over 3.6 million, it is the List of urban areas in the European Union, eighth-largest urban area in the European Union (EU). The Municipality of Athens (also City of Athens), which constitutes a small administrative unit of the entire urban area, had a population of 643,452 (2021) within its official limits, and a land area of . Athens is one of the List of oldest continuously inhabited cities, world's oldest cities, with its recorded history spanning over 3,400 years, and its earliest human presence beginning somewhere between the 11th and 7th millennia BCE. According to Greek mythology the city was named after Athena, the ancient Greek goddess of wisdom, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanos (Athens)
The Eridanos or Eridanus (; ) was a river in Athens mentioned in Greek mythology and historiography. Mythical stream Eridanus was the 'deep-swirling' river-god son of the Titans Oceanus and his sister-wife Tethys. He was the father of Zeuxippe, mother of the Argonauts Butes and Eribotes by Teleon. Eridanus may be the same or different with his another river-god namesake. Real river Eridanus was the small stream that flowed from a source in the foothills of the Lykabettos, through the Agora of ancient Athens in Greece to the archaeological site of the Kerameikos, where its bed is still visible. In this area lives a population of Greek tortoise. Its course has been for the most part covered since ancient times, and was only visible outside the ancient walls in the district of Kerameikos. The river was rediscovered during the excavations for the Athens Metro subway in the late 1990s, and its waters caused considerable technical problems at times. Because of the Metro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Po River
The Po ( , ) is the longest river in Italy. It flows eastward across northern Italy, starting from the Cottian Alps. The river's length is , or if the Maira (river), Maira, a right bank tributary, is included. The headwaters of the Po are formed by a Spring (hydrology), spring seeping from a stony hillside at Pian del Re, a flat place at the head of the Val Po under the northwest face of Monviso. The Po then extends along the 45th parallel north before ending at a delta projecting into the Adriatic Sea near Venice. Draining a basin of , the Po is characterized by its large Discharge (hydrology), discharge (several List of rivers by length, rivers over 1,000 km have a discharge inferior or equal to the Po). It is, with the Rhône and Nile, one of the three Mediterranean rivers with the largest water discharge. As a result of its characteristics, the river is subject to heavy flooding. Consequently, over half its length is controlled with Levee, embankments. The river flows throu ... [...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] |
List Of Constellations By Area
The International Astronomical Union (IAU) designates 88 constellations of stars. In the table below, they are ranked by the solid angle that they subtend in the sky, measured in square degrees and millisteradians. These solid angles depend on arbitrary boundaries between the constellations: the list below is based on constellation boundaries drawn up by Eugène Delporte in 1930 on behalf of the IAU and published in ''Délimitation scientifique des constellations'' (Cambridge University Press). Before Delporte's work, there was no standard list of the boundaries of each constellation. Delporte drew the boundaries along vertical and horizontal lines of right ascension and declination; however, he did so for the epoch B1875.0, which means that due to precession of the equinoxes, the borders on a modern star map (e.g., for epoch J2000) are already somewhat skewed and no longer perfectly vertical or horizontal. This skew will increase over the centuries to come. However, this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
