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Ionnas Focas
Jean-Henri Focas ( el, Ιωάννης Ε. Φωκάς; 20 July 1909 – 3 January 1969) was a Greek-French astronomer, painter, designer, illustrator, astrophysicists, photographer, celestial cartographer and spoke five languages. He performed visual studies of planetary surfaces from the National Observatory of Athens, Pic du Midi, and Meudon Great Refractor. Jean is responsible for creating the most highly visual map of Mars ever created by a visual observer of the planet. He developed special photographic equipment to photograph celestial phenomena. In 1961, he published ''Étude Photométrique et Polarimétrique des Phénomènes Saisonniers de la Planéte Mar (Photometric and Polarimetric Study of the Seasonal Phenomena of the Planet Mars)'' which became a classic on the subject of polarimetric investigation of Mars. A crater on the Moon and a crater on Mars were named after him because of his contribution to the field. Jean was born on the Greek island of Corfu. When ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athens
Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates and is the capital of the Attica region and is one of the 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 BC. Classical Athens was a powerful city-state. It was a centre for the arts, learning and philosophy, and the home of Plato's Academy and Aristotle's Lyceum. It is widely referred to as the cradle of Western civilization and the birthplace of democracy, largely because of its cultural and political influence on the European continent—particularly Ancient Rome. In modern times, Athens is a large cosmopolitan metropolis and central to economic, financial, industrial, maritime, political and cultural life in Gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarimetry
Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically polarimetry is done on electromagnetic waves that have traveled through or have been reflected, refracted or diffracted by some material in order to characterize that object. Plane polarized light: According to the wave theory of light, an ordinary ray of light is considered to be vibrating in all planes of right angles to the direction of its propagation. If this ordinary ray of light is passed through a nicol prism, the emergent ray has its vibration only in one plane. Applications Polarimetry of thin films and surfaces is commonly known as ellipsometry. Polarimetry is used in remote sensing applications, such as planetary science, astronomy, and weather radar. Polarimetry can also be included in computational analysis of waves. For example, radars often consider wave polarization in post-processing to imp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phokas (Byzantine Family)
Phokas ( grc-gre, Φωκᾶς, ''Phōkâs'') or Phocas (from Latin), feminine form Phokaina or Phocaina (, ''Phṓkaina''), was the name of a Byzantine aristocratic clan from Cappadocia, which in the 9th and 10th centuries provided a series of high-ranking generals and an emperor, Nikephoros II Phokas (963–969). Its members and their clients monopolized the high-command positions of the Byzantine army for much of the 10th century and led the successful Byzantine offensive against the Arabs in the East. As one of the leading families of the Anatolian military aristocracy, the Phokades were also involved in a series of rebellions that laid claim to power and challenged the emperors at Constantinople. Their power was eventually broken by Basil II (r. 976–1025), and the family declined in importance after the 11th century. History Origin and early members According to Michael Attaleiates, the family descended from the ancient Roman ''gens Fabia'', while Ali ibn al-Athir ascribed th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focas (Martian Crater)
Focas may refer to: * Focas (lunar crater), a crater on the Moon * Focas (Martian crater), a crater on Mars * Jean Focas (1909–1969), Greek-French astronomer * Spiros Focás (born 1937), Greek actor See also * Phocas Phocas ( la, Focas; grc-gre, Φωκάς, Phōkás; 5475 October 610) was Eastern Roman emperor from 602 to 610. Initially, a middle-ranking officer in the Eastern Roman army, Phocas rose to prominence as a spokesman for dissatisfied soldiers ... * Foca (other) * Fokas (other) {{disambiguation, surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernard Lyot
Bernard Ferdinand Lyot (27 February 1897 in Paris – 2 April 1952 in Cairo) was a French astronomer. Biography An avid reader of the works of Camille Flammarion, he became a member of the Société Astronomique de France in 1915 and made his first observations using the society's telescope on rue Serpente in Paris. He soon acquired a telescope and soon upgraded to a . From graduation in 1918 until 1929, he worked as a demonstrator at the École Polytechnique and studied engineering, physics, and chemistry at the University of Paris. From 1920 until his death he worked for the Meudon Observatory, where in 1930 he earned the title of ''Joint Astronomer of the Observatory''. After gaining the title, he earned a reputation of being an expert of polarized and monochromatic light. Throughout the 1930s, he labored to perfect the coronagraph, which he invented to observe the corona without having to wait for a solar eclipse. In 1938, he showed a movie of the corona in action to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophotography
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum photons over these long periods of time. Photography using extended exposure-times revolutionized the field of professional astronomical research, recording hundreds of thousands of new stars, and nebulae invisible to the human eye. Specialized and ever-larger optical telescopes were constructed as essentially big cameras to rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometry (astronomy)
Photometry, from Greek '' photo-'' ("light") and '' -metry'' ("measure"), is a technique used in astronomy that is concerned with measuring the flux or intensity of light radiated by astronomical objects. This light is measured through a telescope using a photometer, often made using electronic devices such as a CCD photometer or a photoelectric photometer that converts light into an electric current by the photoelectric effect. When calibrated against standard stars (or other light sources) of known intensity and colour, photometers can measure the brightness or apparent magnitude of celestial objects. The methods used to perform photometry depend on the wavelength region under study. At its most basic, photometry is conducted by gathering light and passing it through specialized photometric optical bandpass filters, and then capturing and recording the light energy with a photosensitive instrument. Standard sets of passbands (called a photometric system) are defined to allow a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometer (device)
A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers (opposing ends joined by a frame). The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. Micrometers are also used in telescopes or microscopes to measure the apparent diameter of celestial bodies or microscopic objects. The micrometer used with a telescope was invented about 1638 by William Gascoigne, an English astronomer. History The word ''micrometer'' is a neoclassical coinage ... [...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] |
Earl C
Earl () is a rank of the nobility in the United Kingdom. The title originates in the Old English word ''eorl'', meaning "a man of noble birth or rank". The word is cognate with the Scandinavian form ''jarl'', and meant "chieftain", particularly a chieftain set to rule a territory in a king's stead. After the Norman Conquest, it became the equivalent of the continental count (in England in the earlier period, it was more akin to a duke; in Scotland, it assimilated the concept of mormaer). Alternative names for the rank equivalent to "earl" or "count" in the nobility structure are used in other countries, such as the ''hakushaku'' (伯爵) of the post-restoration Japanese Imperial era. In modern Britain, an earl is a member of the peerage, ranking below a marquess and above a viscount. A feminine form of ''earl'' never developed; instead, ''countess'' is used. Etymology The term ''earl'' has been compared to the name of the Heruli, and to runic ''erilaz''. Proto-Norse ''eri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965. and In 2011, the Observatory was named one of "The World's 100 Most Important Places" by Time Magazine. It was at the Lowell Observatory that the dwarf planet Pluto was discovered in 1930 by Clyde Tombaugh. The observatory was founded by astronomer Percival Lowell of Boston's Lowell family and is overseen by a sole trustee, a position historically handed down through the family. The first trustee was Lowell's third cousin Guy Lowell (1916–1927). Percival's nephew Roger Putnam served from 1927 to 1967, followed by Roger's son Michael (1967–1987), Michael's brother William Lowell Putnam III (1987–2013), and current trustee W. Lowell Putnam. Multiple astronauts attended the Lowell Observatory in 1963 while the moon was being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Four Corners region with Utah to the north, Colorado to the northeast, and New Mexico to the east; its other neighboring states are Nevada to the northwest, California to the west and the Mexican states of Sonora and Baja California to the south and southwest. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912. Historically part of the territory of in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase. Southern Arizona is known for its desert cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
