An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, moons and galaxies – in either observational or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. Related but distinct subjects like physical cosmology. Astronomers fall under either of two main types: observational and theoretical. Observational astronomers analyze the data. In contrast, theoretical astronomers create and investigate models of things that cannot be observed; because it takes millions to billions of years for a system of stars or a galaxy to complete a life cycle, astronomers must observe snapshots of different systems at unique points in their evolution to determine how they form and die. They use these data to create models or simulations to theorize how different celestial objects work.
Further subcategories under these two main branches of astronomy include planetary astronomy, galactic astronomy, or physical cosmology. Astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws. Today, that distinction has disappeared and the terms "astronomer" and "astrophysicist" are interchangeable. Professional astronomers are educated individuals who have a PhD in physics or astronomy and are employed by research institutions or universities, they spend the majority of their time working on research, although they quite have other duties such as teaching, building instruments, or aiding in the operation of an observatory. The number of professional astronomers in the United States is quite small; the American Astronomical Society, the major organization of professional astronomers in North America, has 7,000 members. This number includes scientists from other fields such as physics and engineering, whose research interests are related to astronomy.
The International Astronomical Union comprises 10,145 members from 70 different countries who are involved in astronomical research at the PhD level and beyond. Contrary to the classical image of an old astronomer peering through a telescope through the dark hours of the night, it is far more common to use a charge-coupled device camera to record a long, deep exposure, allowing a more sensitive image to be created because the light is added over time. Before CCDs, photographic plates were a common method of observation. Modern astronomers spend little time at telescopes just a few weeks per year. Analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers' time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes. Most universities have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field.
Those who become astronomers have a broad background in maths and computing in high school. Taking courses that teach how to research and present papers are invaluable. In college/university most astronomers get a PhD in physics. While there is a low number of professional astronomers, the field is popular among amateurs. Most cities have amateur astronomy clubs that meet on a regular basis and host star parties; the Astronomical Society of the Pacific is the largest general astronomical society in the world, comprising both professional and amateur astronomers as well as educators from 70 different nations. Like any hobby, most people who think of themselves as amateur astronomers may devote a few hours a month to stargazing and reading the latest developments in research. However, amateurs span the range from so-called "armchair astronomers" to the ambitious, who own science-grade telescopes and instruments with which they are able to make their own discoveries and assist professional astronomers in research.
List of astronomers List of women astronomers List of Muslim astronomers List of French astronomers List of Hungarian astronomers List of Russian astronomers and astrophysicists List of Slovenian astronomers Dallal, Ahmad. "Science and Technology". In Esposito, John; the Oxford History of Islam. Oxford University Press, New York. ISBN 0-300-15911-0. Kennedy, E. S.. "A Survey of Islamic Astronomical Tables. 46. Philadelphia: American Philosophical Society. Toomer, Gerald. "Al-Khwārizmī, Abu Jaʿfar Muḥammad ibn Mūsā". In Gillispie, Charles Coulston. Dictionary of Scientific Biography. 7. New York: Charles Scribner's Sons. ISBN 0-684-16962-2. American Astronomical Society European Astronomical Society International Astronomical Union Astronomical Society of the Pacific Space's astronomy news
Narasimhavarman I or Narasimha Varma I was a king of the Pallava dynasty who ruled South India from 630–668 AD. He shared his father Mahendravarman I's love of art and completed the work started by Mahendravarman in Mamallapuram. During his reign famous Pancha Rathas Temple was constructed, Rock Cut Temple, a UNESCO World Heritage site, he avenged his father's defeat at the hands of the Chalukya king, Pulakeshin II in the year 642 AD. Narasimhavarman I was known as Mahamalla, Mamallapuram was named after him, it was in 640 AD, that the Chinese traveller Hiuen Tsang visited Kanchipuram. Narasimhavarman I was a devotee of Shiva; the great Nayanar saints like Appar and Tirugnanasambandar lived during his reign. Narasimhavarman I was succeeded by his son Mahendravarman II in the year 668 AD. Narasimhavarman I is claimed to be one of the 12 Indian kings who never lost on the battlefield to their enemies, the others being Ajatashatru, Chandragupta Maurya, Karikala Chola, Cheran Senguttuvan, Sri krishnadevaraya of Vijayanagar empire, Chola king Rajasuyam Vaetta Perunarkilli, who completed military Rajasuyam sacrifice, Pandyan Nedunchezhian of the Sangam age, great Pallava Nayanmar saint Rajasimha, Rajaraja Chola I, his great warrior son Rajendra Chola.
Pulakeshin II, a deccan king, had raided various northern Pallava provinces and forts. However, he was unable to capture the Pallava capital of Kanchipuram; this led to a long conflict between the Chalukyas and the Pallavas. Pulakeshin II again attempted to seize the Pallava capital and undertook another expedition several years later. However, the Pallava reign had moved on to Narasimhavarman I by then. Narasimhavarman defeated the Chalukyas in several battles, including one at Manimangalam 20 miles to the east of Kanchipuram; the king states. Encouraged by this victory, Narasimhavarman led his army along with his general Paranjothi and invaded Vatapi defeating and killing the Chalukya king Pulakeshin II in 642 CE; the city was never a capital again. He returned victorious to Kanchipuram, was given the title Vatapikondan, his general Paranjothi was known well for his devotion to Lord Siva and as one of the 63 Nayanmar saints, is said to have indeed destroyed the city of Vatapi under the command of Narasimhavarman I.
Sekkizhaar's work 12th tirumurai credits this siruttondar of having destroyed the evil kali as manifested by the deccan enemy of pallavas. He is known as'Siruthonttar', a dutiful warrior and a practicing medic who had "mastered several treatises in medicine"; this vikramakesari had at the insistence of Lord Sivan sacrificed his child without any qualms. There was a confusion as to whether the Ganesha at a temple in Chengattankudy could have been a result of this invasion but this seems not to be true because the temple and association of Lord Ganesha with the same are well described in sthalapuranam or the literature discussing the importance of the place; the Ganesha seems to be installed several thousands of years ago in a previous epoch. Many grants refer to this event as: "kilisayoneriva vimattita vathapi" or the one who destroyed Vatapi, the same way Sage Agastya had killed a demon by that name long ago; the Sinhalese prince Manavarma lived at the court of Narasimhavarman and had helped him crush his enemy Pulakeshin II.
In return, Narasimhavarman supplied Manavarma twice with an army to invade Sri Lanka. The second attack was successful. Manavarma occupied Sri Lanka, over which he is supposed to have ruled from A. D. 691 to 726. The Kasakudi copper plates refer to Narasimhavarman's conquest of Sri Lanka; the Mahavamsa confirms these facts. Kalki Krishnamurthy's work, Sivagamiyin Sabadham, is based on Narasimhavarman's early years and his battles with the Chalukyas. Kalki Krishnamurthy's Parthiban kanavu is based on the years of Narasimhavarman's rule. Keay, John. India: A History. Grove Press. ISBN 0-8021-3797-0. Sastri, K A N. A History of South India. New Delhi, India: Oxford University Press. Ancient India, R. C. Majumdar, Ancient India, K. A. Nilakanta Sastri Inscriptions of India -- Complete listing of historical inscriptions from Indian temples and monuments
The automotive industry in Sweden is associated with passenger car manufacturers Volvo Cars and Saab Automobile but Sweden is home of two of the largest truck manufacturers in the world: Volvo AB and Scania AB. The automotive industry is dependent on export as some 85 percent of the passenger cars and 95 percent of the heavy vehicles are sold outside of Sweden; the automotive industry and its sub-contractors is a major part of Swedish industry. In 2011 around 110,000 people were employed and the export income of 150 billion SEK accounted for 12 per cent of Sweden's export income. During 2009 128,738 passenger cars and 27,698 heavy vehicles were built in Sweden; the first Swedish automobile was a steam car built in 1891-92 by Anders Cederholm. They planned to use it for transportation between their home in Ystad and their summer house outside town; the automobile was destroyed in Sweden's first automobile accident but the Cederholm brothers soon built a second, improved version of their steam car reusing many parts from the first one.
The car is preserved in a museum in Skurup. In 1898 Gustaf Erikson at Surahammars Bruk built an automobile with an internal combustion engine for Vabis in Södertälje. Erikson continuously improved his car until Vabis was satisfied, started production of automobiles and trucks in 1902. Harald Håkansson built the first electric car in Sweden on behalf of AB Atlas in 1900; the project never went beyond this single prototype. The bicycle manufacturer Maskinfabriks-aktiebolaget Scania in Malmö started producing automobiles and trucks in 1902; the company amalgamated with Vabis in 1911. The new company concentrated their production of automobiles and light trucks to Södertälje while the Malmö plant built heavy trucks. In 1903, Tidaholms Bruk built. After a second Tor prototype the company started production on a larger scale under the name Tidaholm. Tidaholm built a small number of automobiles but their main products were heavy trucks and buses. Åtvidabergs Vagnfabrik used an American high wheeler as model for their automobile in 1910.
This vehicle was so outdated. The rest of the cars were turned into draisines for railroad inspection. Swedish aircraft manufacturer AB Thulinverken in Landskrona started building automobiles in 1920; the car was based on a design from German manufacturer AGA. The production was limited and when Volvo started production in 1927 Thulin left the automobile industry after some 500 cars had been built. In 1921 Scania-Vabis went bankrupt. After reconstruction the company decided to abandon passenger car production and close their plant in Malmö and focus on truck production in Södertälje; the situation got better when Scania-Vabis received a large order for buses from the Swedish postal service. The large and powerful Scania-Vabis trucks were used for snow removal and other road maintenance work in Sweden. In the 1920s Ford Motor Company and General Motors opened assembly plants in Sweden. Chrysler Corporation cooperated with Svenska Bilfabriken AB. Ford's factory in Stockholm was active until mid-1950s.
Volvo started production of passenger cars and light trucks in Gothenburg in 1927, backed by ball bearing manufacturer SKF. Production of passenger cars was limited during the first decades but the trucks were successful and kept the company profitable. During the great depression Tidaholm started losing money and halted vehicle production in 1934; some 850 vehicles had been manufactured since 1903. AB Nyköpings Automobilfabrik started licence assembly in 1937, first from American Chrysler Corporation and on from European companies like Standard Motor Company and Simca. Car assembly stopped when Saab bought ANA in 1960. After the Second World War military aircraft manufacturer Saab AB started looking for a civilian product to fill their workshops; the answer was passenger cars. Production of the small Saab automobile started in Trollhättan in 1949; the powertrain with a two-stroke engine and front-wheel drive resembled the German DKW, popular in Sweden before the war, while the unibody showed influence from the aircraft industry.
Both Volvo and Scania-Vabis begun exporting their trucks in the 1930s but it wasn't until the 1950s volumes started rising. Like other Swedish products the trucks were needed in the rebuilding of Europe after the war. By the end of the decade Volvo and Saab, like the rest of the European automobile industry, started exporting their passenger cars to the vast American market. Volvo and Saab were successful in rallying in the 1960s. Saabs successes with their top driver Erik Carlsson in the Monte Carlo Rally and the RAC Rally opened up a new market for the small automobile maker in the United Kingdom; the US and Britain would remain the sole export markets for Saab, which in the end would prove fatal for production volume. Between 1969 and 1971 Kalmar Verkstad produced a purpose-built vehicle for the Swedish postal service called Tjorven. Kalmar Verkstad experimented with a semi-trailer truck, but this project never materialized. In 1969 the Wallenberg family merged their aircraft and automobile manufacturer Saab with their truck manufacturer Scania-Vabis into one company, called Saab-Scania.
One and a half year earlier the truck manufacturer dropped the Vabis name and their products have since been sold under the name Scania only. During the general decline of the automotive industry following the 1973 oil crisis and Saab-Scania felt they were too small to survive on their own in the long run. In 1977 plans were presented on a merger between the two companies; the plan fell apart due to resistance from Saab-Scania's shareholders. Volvo launched an important new model, th