51 relations: Angular diameter, Apparent magnitude, Arabic, Asterism (astronomy), Bayer designation, Birkhäuser, Bright Star Catalogue, Catalogues of Fundamental Stars, Celestial cartography, Chinese language, Constellation, Delta Hydrae, Durchmusterung, Effective temperature, Epoch (astronomy), Epsilon Hydrae, Eta Hydrae, Extinction (astronomy), Flamsteed designation, Giant star, Groote Eylandt, Henry Draper Catalogue, Hipparcos, Hydra (constellation), IAU Working Group on Star Names, International Celestial Reference System, Johann Elert Bode, Latinisation of names, Light-year, Limb darkening, Minute and second of arc, Monthly Notices of the Royal Astronomical Society, NASA, Nostril, Omega Hydrae, Rho Hydrae, SIMBAD, Smithsonian Astrophysical Observatory Star Catalog, Solar luminosity, Solar mass, Solar radius, Star, Stellar atmosphere, Stellar classification, Stellar evolution, Stellar parallax, Sun, Theta Hydrae, Willow (Chinese constellation), Yale University, ..., Zeta Hydrae. Expand index (1 more) » « Shrink index
The angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view.
The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth.
Arabic (العَرَبِيَّة) or (عَرَبِيّ) or) is a Central Semitic language that first emerged in Iron Age northwestern Arabia and is now the lingua franca of the Arab world. It is named after the Arabs, a term initially used to describe peoples living from Mesopotamia in the east to the Anti-Lebanon mountains in the west, in northwestern Arabia, and in the Sinai peninsula. Arabic is classified as a macrolanguage comprising 30 modern varieties, including its standard form, Modern Standard Arabic, which is derived from Classical Arabic. As the modern written language, Modern Standard Arabic is widely taught in schools and universities, and is used to varying degrees in workplaces, government, and the media. The two formal varieties are grouped together as Literary Arabic (fuṣḥā), which is the official language of 26 states and the liturgical language of Islam. Modern Standard Arabic largely follows the grammatical standards of Classical Arabic and uses much of the same vocabulary. However, it has discarded some grammatical constructions and vocabulary that no longer have any counterpart in the spoken varieties, and has adopted certain new constructions and vocabulary from the spoken varieties. Much of the new vocabulary is used to denote concepts that have arisen in the post-classical era, especially in modern times. During the Middle Ages, Literary Arabic was a major vehicle of culture in Europe, especially in science, mathematics and philosophy. As a result, many European languages have also borrowed many words from it. Arabic influence, mainly in vocabulary, is seen in European languages, mainly Spanish and to a lesser extent Portuguese, Valencian and Catalan, owing to both the proximity of Christian European and Muslim Arab civilizations and 800 years of Arabic culture and language in the Iberian Peninsula, referred to in Arabic as al-Andalus. Sicilian has about 500 Arabic words as result of Sicily being progressively conquered by Arabs from North Africa, from the mid 9th to mid 10th centuries. Many of these words relate to agriculture and related activities (Hull and Ruffino). Balkan languages, including Greek and Bulgarian, have also acquired a significant number of Arabic words through contact with Ottoman Turkish. Arabic has influenced many languages around the globe throughout its history. Some of the most influenced languages are Persian, Turkish, Spanish, Urdu, Kashmiri, Kurdish, Bosnian, Kazakh, Bengali, Hindi, Malay, Maldivian, Indonesian, Pashto, Punjabi, Tagalog, Sindhi, and Hausa, and some languages in parts of Africa. Conversely, Arabic has borrowed words from other languages, including Greek and Persian in medieval times, and contemporary European languages such as English and French in modern times. Classical Arabic is the liturgical language of 1.8 billion Muslims and Modern Standard Arabic is one of six official languages of the United Nations. All varieties of Arabic combined are spoken by perhaps as many as 422 million speakers (native and non-native) in the Arab world, making it the fifth most spoken language in the world. Arabic is written with the Arabic alphabet, which is an abjad script and is written from right to left, although the spoken varieties are sometimes written in ASCII Latin from left to right with no standardized orthography.
In observational astronomy, an asterism is a popular known pattern or group of stars that are recognised in the night sky.
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name.
Birkhäuser is a former Swiss publisher founded in 1879 by Emil Birkhäuser.
The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the naked eye from Earth.
The Catalogue of Fundamental Stars is a series of six astrometric catalogues of high precision positional data for a small selection of stars to define a celestial reference frame, which is a standard coordinate system for measuring positions of stars.
Celestial cartography, uranography, astrography or star cartography is the fringe of astronomy and branch of cartography concerned with mapping stars, galaxies, and other astronomical objects on the celestial sphere.
Chinese is a group of related, but in many cases mutually unintelligible, language varieties, forming a branch of the Sino-Tibetan language family.
Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.
The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.
Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.
Christmas traditions vary from country to country.
A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices.
Delta Hydrae, Latinized from δ Hydrae, is a double star in the equatorial constellation of Hydra.
In astronomy, Durchmusterung or Bonner Durchmusterung (BD), is the comprehensive astrometric star catalogue of the whole sky, compiled by the Bonn Observatory (Germany) from 1859 to 1903.
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation.
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.
Epsilon Hydrae (ε Hydrae, abbreviated Epsilon Hya, ε Hya) is a is a multiple star system of a combined third magnitude in the constellation of Hydra.
Eta Hydrae (η Hya) is the Bayer designation for a star in the equatorial constellation of Hydra.
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer.
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England.
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature.
Groote Eylandt is the largest island in the Gulf of Carpentaria and the fourth largest island in Australia.
The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993.
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees.
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.
The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU).
Johann Elert Bode (19 January 1747 – 23 November 1826) was a German astronomer known for his reformulation and popularisation of the Titius–Bode law.
Latinisation or Latinization is the practice of rendering a non-Latin name (or word) in a Latin style.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
Limb darkening is an optical effect seen in stars (including the Sun), where the center part of the disk appears brighter than the edge or limb of the image.
A minute of arc, arcminute (arcmin), arc minute, or minute arc is a unit of angular measurement equal to of one degree.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.
In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.
A nostril (or naris, plural nares) is one of the two channels of the nose, from the point where they bifurcate to the external opening.
Omega Hydrae, Latinized from ω Hydrae, is a golden-hued star in the equatorial constellation of Hydra, located to the west-southwest of the brighter star Zeta Hydrae.
Rho Hydrae, Latinized from ρ Hya, is a binary star in the equatorial constellation of Hydra.
SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is an astronomical database of objects beyond the Solar System.
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue.
The solar luminosity,, is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
Solar radius is a unit of distance used to express the size of stars in astronomy.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Stellar evolution is the process by which a star changes over the course of time.
Stellar parallax is the apparent shift of position of any nearby star (or other object) against the background of distant objects.
The Sun is the star at the center of the Solar System.
Theta Hydrae, Latinized from θ Hydrae, is a binary star system in the constellation Hydra.
The Willow mansion (柳宿, pinyin: Liǔ Xiù) is one of the Twenty-eight mansions of the Chinese constellations.
Yale University is an American private Ivy League research university in New Haven, Connecticut.
Zeta Hydrae (ζ Hya, ζ Hydrae) is a solitary star in the equatorial constellation of Hydra.
2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.
2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.