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Alpha Ursae Majoris
Alpha Ursae Majoris, Latinised from α Ursae Majoris, formally named Dubhe , is, despite being designated "α" (alpha), the second-brightest object in the northern constellation of Ursa Major. This prominent asterism is known as the Big Dipper, the Plough, and the Great Bear. Alpha Ursae Majoris is the northern of the 'pointers' (or 'guards'), the second being Beta Ursae Majoris, or 'Merak' – this pair of stars point towards Polaris, the North Star. Stellar system α Ursae Majoris is located at a distance of approximately 123 light years from the Sun, based on parallax measurements. It is a spectroscopic binary made up of the stars designated ''α Ursae Majoris A'' and ''α Ursae Majoris B''. The pair orbit at a separation of about 23 astronomical units (AU) with a period of 44.5 years and an eccentricity (ovalness) of 0.44. There is another spectroscopic binary at an angular separation of 7.1 arcminutes, forming a 7th magnitude pair showing an F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ursa Major
Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa Minor, the lesser bear. In antiquity, it was one of the original 48 constellations listed by Ptolemy in the 2nd century AD, drawing on earlier works by Greek, Egyptian, Babylonian, and Assyrian astronomers. Today it is the third largest of the 88 modern constellations. Ursa Major is primarily known from the asterism of its main seven stars, which has been called the " Big Dipper," "the Wagon," "Charles's Wain," or "the Plough," among other names. In particular, the Big Dipper's stellar configuration mimics the shape of the " Little Dipper." Two of its stars, named Dubhe and Merak ( α Ursae Majoris and β Ursae Majoris), can be used as the navigational pointer towards the place of the current northern pole star, Polaris in Ursa Mino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" (宿 ''xiù'') system also took shape around this period, by the time of King Wu Ding (1250–1192 BCE). Detailed records of astronomical observations began during the Warring States period (fourth century BCE) and flourished from the Han period onward. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saptarishi
The Saptarishi () are the seven rishis of ancient India who are extolled in the Vedas, and other Hindu literature. The Vedic Samhitas never enumerate these rishis by name, although later Vedic texts such as the Brahmanas and Upanisads do so. Hinduism An early prototype of the "Saptarishi" concept may stem from the six families associated with the six "Family Books" in the Rigveda Samhita (Mandalas 2–7 in ascending order: Gṛtsamāda, Viśvāmitra, Vāmadeva, Atri, Bhardwaja, Vasiṣṭha). While not a "Family Book", Mandala 8 is mostly attributed to Kaṇva, who could be considered the 7th prototypical Saptarishi. The earliest formal list of the seven rishis is given by Jaiminiya Brahmana 2.218–221: Agastya, Atri, Bhardwaja, Gautama, Jamadagni, Vashistha, and Vishvamitra followed by Brihadaranyaka Upanisad 2.2.6 with a slightly different list: Atri, Bharadwaja, Gautama, Jamadagni, Kashyapa, Vashistha, and Vishvamitra. The late Gopatha Brahmana 1.2.8 ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kratu
Kratu ( sa, क्रतु, lit=strength) is described as one of the manasaputras, the mind-born children of the creator deity, Brahma, in Hinduism. He is also a rishi, who appears in two different ages. He is considered to be one among the seven great sages of the age of the first Manu, the Saptarishis, believed to have originated from the mind of Brahma. In another legend, he is believed to have been born from his father's left eye. Legend In the Svayambhuva Manvantara, Kratu is a Prajapati, a son of Brahma. He is also the son-in-law of Prajapati Kardama. His wife is named Kriya. It is said that he has 60,000 children. Their name is included in the eighth book of the Rigveda. Kratu also has two sisters, Punya and Satyavati (not to be confused with Mahabharata's Satyavati, the great-grandmother of the Pandavas and the Kauravas). He is also stated to be married to Santati in the Puranas, and the pair has sixty thousand children, called the Balakhilyas, who were each of the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hindu
Hindus (; ) are people who religiously adhere to Hinduism. Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for people living in the Indian subcontinent. The term ''"Hindu"'' traces back to Old Persian which derived these names from the Sanskrit name ''Sindhu'' (सिन्धु ), referring to the river Indus. The Greek cognates of the same terms are "''Indus''" (for the river) and "''India''" (for the land of the river). The term "''Hindu''" also implied a geographic, ethnic or cultural identifier for people living in the Indian subcontinent around or beyond the Sindhu (Indus) River. By the 16th century CE, the term began to refer to residents of the subcontinent who were not Turkic or Muslims. Hindoo is an archaic spelling variant, whose use today is considered derogatory. The historical development of Hindu self-identity within the local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IAU Working Group On Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage. The IAU states that it is keen to make a distinction between the terms ''name'' and ''designation''. To the IAU, ''name'' refers to the (usually colloquial) term used for a star in everyday conversation, while ''designation'' is solely alphanumerical, and used almost exclusively in official catalogues and for professional astronomy. (The WGSN notes that transliterated Bayer designations (e.g., Tau Ceti) are considered a special historical case and are treated as designations.) Terms of reference The terms of reference for the WGSN for the period 2016–2018 were approved by the IAU Executive Committee at its meeting on 6 May 2016. In summary, these are to: * establish IAU guidelines for the proposal and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of 2018, the Union had over 13,700 individual members, spanning 90 countries, and 82 national members. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic
Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter de Gruyter GmbH & Co. KG, Berlin/Boston, 2011. Having emerged in the 1st century, it is named after the Arab people; the term "Arab" was initially used to describe those living in the Arabian Peninsula, as perceived by geographers from ancient Greece. Since the 7th century, Arabic has been characterized by diglossia, with an opposition between a standard prestige language—i.e., Literary Arabic: Modern Standard Arabic (MSA) or Classical Arabic—and diverse vernacular varieties, which serve as mother tongues. Colloquial dialects vary significantly from MSA, impeding mutual intelligibility. MSA is only acquired through formal education and is not spoken natively. It is the language of literature, official documents, and formal writ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bayer Designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. The brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas '' Uranometria''. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers (including Nicolas-Louis de Lacaille and Benjamin Apthorp Gould) supplemented Bayer's catalog with entries for southern constellations. Scheme Bayer assigned a lowercase Greek letter (alpha (α), beta (β), gamma (γ), etc.) or a Latin letter (A, b, c, etc.) to each star he catalogued, combined with the Latin name of the star's parent constellation in genitive (possessive) form. The constellation name is frequently abbreviated to a standard three-letter form. For example, Aldebaran in the constellat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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