Medicina Radio Observatory
The Medicina Radio Observatory is an astronomical observatory located 30 km from Bologna, Italy. It is operated by the Institute for Radio Astronomy of the National Institute for Astrophysics of the government of Italy; the site includes: 32-metre diameter parabolic antenna for observing between 23 GHz. The 32-m antenna is used as a single-dish instrument for astrophysical observations, SETI experiments and radar monitoring of Near Earth Objects. In interferometric mode it functions as part of the European VLBI Network. 564 by 640 m multi-element Northern Cross cylindrical-parabolic transit radio telescope for observing at 408 MHz. The Northern Cross Radio Telescope is one of the largest transit radio telescopes in the world. Observations are focused around corresponding to 73.5 cm wavelength. The older receivers of the telescope function with a 2.5 MHz wide frequency band, while the upgraded parts have a 16 MHz bandwidth. The telescope is steerable only in declination, meaning that it can observe objects that are culminating on the local celestial meridian.
The telescope is T-shaped and consists of: E/W arm - Single reflector 560 m x 35 m N/S arm - Array of 64 reflectors 640 m x 23.5 m The telescope can provide 22880 possible theoretical independent beams and has a field of view of 55.47 degrees by 1.8 degrees. The resolution is around 4-5 arcminutes in the North-South direction, 4 arcminutes in the East-West direction. While less than the resolution of large optical telescopes, the amount of radiation which can be gathered with the Northern Cross is much greater, proportional to the mirror surface of 27400 square meters. Northern Cross represents the largest UHF-band antenna in the Northern hemisphere, with an aperture efficiency of 60%, making it second in the world, after the Arecibo radio telescope; this allows the Northern Cross to identify and measure faint sources, making the telescope is suitable to extragalactic researches. There are plans upgrade of the East-West arm telescope to a LOFAR SuperStation, due to the good performances of a cylindrical-parabolic antenna in the 100-700 MHz frequency range.
Since LOFAR operates in the 120-240 MHz range, some of the sensors on the Northern Cross Radio Telescope, optimized for 408 MHz, will have to be replaced with broadband antennas. This installation will have an effective area much larger than any other remote LOFAR station. If extended to the whole 22000 square meters area of the East-West arm, this single element effective area of 20 standard remote LOFAR stations; the resulting system will provide signification improvement in observation sensitivity. The Cross is used as a pathfinder for the Square Kilometre Array; the work is focused on studying the amplification and filtering of signals between the LNA output and the Analog-to-Digital Converter input for the SKA. The Medicina Radio Observatory is studying all problems related to "antenna array implementation" through a prototype installation called MAD; the observatory staff have built new receiver demonstrators for the SKA called BEST, part of the EU-funded SKADS programme. The project started in 2005 and finished in 2009.
It involved the installation of the new receivers on some reflectors of the North-South section of the Northern Cross telescope, along with new analog fiber-optic and coaxial digital finks from the front-end receiver boxes to the back-ends. The BEST project was divided in three parts: BEST-1 - 4 new receivers were installed on a single reflector of the North-South arm. BEST-2 - 32 receivers were installed on 8 reflectors of the North-South arm. BEST-3lo focused on lower frequencies - between 120-240 MHz. Log periodic antennas optimized for 120-240 MHz, along with 18 receivers were installed on part of the East-West arm. There is an ongoing effort to use the 32 meter dish as a receiver for radar-based tracking system artificial satellites and space debris in Earth orbit; the system functions as a bistatic radar, where an emitter located in a different location sends a signal, which bounces off objects in orbit and the echo is picked up by a receiver. The 32 meter dish acts as receiver, while the Yevpatoria 70 meter located in Crimea, functions as a transmitter.
The systems can either track debris to determine their orbit more or utilize a technique called beam park, where the transmitting and receiving antennas are kept fixed at a given position and the debris pass in and out of the observed area. The measurements obtain through such a system can be used to determine object radar cross-section, time of peak occurrence, polarization ratio, bistatic doppler shift and target rotation. In one of the carried-out tests, Yevpatoria-Medicina system was able to detect an object with an estimated radar cross section of 0.0002 square meter, created by the Iridium 33 and Kosmos-2251 satellite collision. The system can function as a multistatic radar using the 32 meter receivers at Medicina, the Noto Radio Observatory in Italy and the Ventspils Starptautiskais Radioastronomijas Centrs in Latvia; the Northern Cross radio telescope has been part of space debris tracking studies, utilized as a multiple-beam receiver for a bistatic radar system. The first tested configuration is a quasi-monostatic radar system, with a 3 m dish as transmitter, located in Bagnara - 20 km from the receiver.
The second configuration was a simulation of a true bistatic radar system with 7 m dish as transmitter located at the s
Teramo is a city and comune in the Italian region of Abruzzo, the capital of the province of Teramo. The city, 150 kilometres from Rome, is situated between the highest mountains of the Apennines and the Adriatic coast; the town is located by the confluence of the Vezzola and Tordino rivers, on a hillside area where the terrain features along with the Mediterranean climate make the territory rich in vineyards and olive groves. The economy of the town is based on activities connected with agriculture and commerce, as well as a sound industrial sector: textiles, engineering, building materials and ceramics. Teramo can be reached from the A24 motorways; the climate is fresh-temperate. In the coolest month temperatures average 5.5 °C, in the warmest month they average 24 °C. In the winter time though they can experience copious amounts of snowfall, as in 2005; the precipitations are not frequent and concentrated in late spring. The summers are characterized by days of somewhat intense heat. Interamna was the name of several cities in different parts of Italy.
Its etymology pointed out by Varro and Festus, indicates their position at the confluence of two streams. The form "Interamnium", the ethnic form Interamnis are found, but more rarely; the name referred to the two rivers Tordino, between which it lies. The name is defined in extant manuscripts of the Liber Coloniarum into Teramne, whence its modern form of Teramo, but in the Middle Ages it appears to have been known by the name of Aprutium, supposed to be a corruption of Praetutium, or rather of the name of the people Praetutii, applied to their chief city. Thus the name Abrutium is present among the cities of Picenum enumerated by the Geographer of Ravenna; the name has been retained in that of Abruzzo, now a region of Italy. A settlement of the 1st millennium BC and some buildings of ancient Italic tribes were the object of archaeological excavations; the most ancient historical remains were found in the outskirts of the city in the neighborhood Madonna delle grazie, among many, a burial place with a dagger and a halberd were found.
The development of the old settlement was due to the commercial center founded by the Etruscan and Phoenician civilization. According to the Roman author Sextus Julius Frontinus, the ancient Perut or Pretut developed in dimensions and importance until it became the capital of the Praetutii tribe. In the battle of Sentinum, the Romans defied the Italian confederation (Sabellians, Etrusci and their allies the Gauls, starting the Samnite Wars. In 290 BC the Sabine area, along with the Praetutii’s region was occupied by the legions sent by the consul general Manius Curius Dentatus; the city took the Latin name of Interamnia Praetuttorium. During the reign of Augustus Interamnia is included in the Picenum district; the area of the current province was divided from south to north into the Ager Hatrianus, Ager Praetutianus and Ager Palmense. After the Second Social War Interamnia became a municipium; the city lost the status of Municipium because of the participation of Lucius Cornelius Sulla in the Social war, but the city will subsequently regain it for expressed will of Julius Caesar.
During the Roman age, thanks to its nearness to the capital of the empire, the city lived a prosperous and favorable moment as proven by the numerous mosaics, thermal baths and the amphitheater remains. As historians like Ptolemy and Pliny remember, the city reached its best period under the emperor Hadrian, with the constructions of the temples dedicated to Mars and Apollo. Little is known about Teramo in the early Middle Ages, after first destruction of the city in the year 410 by the Visigoths under Alaric I; the Ostrogoths ruled Interamnia 552–554 AD. Right after the Gothic War, the city became a Byzantine possession. Teramo was included in the Marchia Firmana, part of the Exarchate of Ravenna, it was a Lombard fief and part of the Duchy of Spoleto. In 1129 the city was conquered as part of the County of Apulia. In 1140 it became a possession of Roger II of the first King of Sicily. During the strife following Roger's coronation, Teramo was destroyed by a Norman force under Robert II of Loritello.
Only the tower of Piazza Sant’Anna was saved from this sack. In the 1268 the domination of the House of Hohenstaufen, who had inherited Sicily from Roger II's line, ended; the ecclesiastical authority of the Aprutina Diocese, led by the bishops Rainaldo Acquaviva, Niccolò degli Arcioni, Stefano da Teramo and Pietro di Valle boosted the city's economy, as witnessed by the construction of castles, churches and palaces along with the great privileges granted by the sovereigns. Within the following two centuries Teramo became part of the Kingdom of Naples; the 15th century saw the struggles between the most important families of the city. The exemplary hanging of 13 followers of Melatino’s family is still remembered in a stone shield in the center of the city; the monument represents two heads with their tongues out under the writing “A lo parlare agi mesura”. During the first years of the century, the tyrant Antonello de Valle was assass
Italy the Italian Republic, is a country in Southern Europe. Located in the middle of the Mediterranean Sea, Italy shares open land borders with France, Austria and the enclaved microstates San Marino and Vatican City. Italy covers an area of 301,340 km2 and has a temperate seasonal and Mediterranean climate. With around 61 million inhabitants, it is the fourth-most populous EU member state and the most populous country in Southern Europe. Due to its central geographic location in Southern Europe and the Mediterranean, Italy has been home to a myriad of peoples and cultures. In addition to the various ancient peoples dispersed throughout modern-day Italy, the most famous of which being the Indo-European Italics who gave the peninsula its name, beginning from the classical era and Carthaginians founded colonies in insular Italy and Genoa, Greeks established settlements in the so-called Magna Graecia, while Etruscans and Celts inhabited central and northern Italy respectively; the Italic tribe known as the Latins formed the Roman Kingdom in the 8th century BC, which became a republic with a government of the Senate and the People.
The Roman Republic conquered and assimilated its neighbours on the peninsula, in some cases through the establishment of federations, the Republic expanded and conquered parts of Europe, North Africa and the Middle East. By the first century BC, the Roman Empire emerged as the dominant power in the Mediterranean Basin and became the leading cultural and religious centre of Western civilisation, inaugurating the Pax Romana, a period of more than 200 years during which Italy's technology, economy and literature flourished. Italy remained the metropole of the Roman Empire; the legacy of the Roman Empire endured its fall and can be observed in the global distribution of culture, governments and the Latin script. During the Early Middle Ages, Italy endured sociopolitical collapse and barbarian invasions, but by the 11th century, numerous rival city-states and maritime republics in the northern and central regions of Italy, rose to great prosperity through shipping and banking, laying the groundwork for modern capitalism.
These independent statelets served as Europe's main trading hubs with Asia and the Near East enjoying a greater degree of democracy than the larger feudal monarchies that were consolidating throughout Europe. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science and art. Italian culture flourished, producing famous scholars and polymaths such as Michelangelo, Leonardo da Vinci, Raphael and Machiavelli. During the Middle Ages, Italian explorers such as Marco Polo, Christopher Columbus, Amerigo Vespucci, John Cabot and Giovanni da Verrazzano discovered new routes to the Far East and the New World, helping to usher in the European Age of Discovery. Italy's commercial and political power waned with the opening of trade routes that bypassed the Mediterranean. Centuries of infighting between the Italian city-states, such as the Italian Wars of the 15th and 16th centuries, left the region fragmented, it was subsequently conquered and further divided by European powers such as France and Austria.
By the mid-19th century, rising Italian nationalism and calls for independence from foreign control led to a period of revolutionary political upheaval. After centuries of foreign domination and political division, Italy was entirely unified in 1871, establishing the Kingdom of Italy as a great power. From the late 19th century to the early 20th century, Italy industrialised, namely in the north, acquired a colonial empire, while the south remained impoverished and excluded from industrialisation, fuelling a large and influential diaspora. Despite being one of the main victors in World War I, Italy entered a period of economic crisis and social turmoil, leading to the rise of a fascist dictatorship in 1922. Participation in World War II on the Axis side ended in military defeat, economic destruction and the Italian Civil War. Following the liberation of Italy and the rise of the resistance, the country abolished the monarchy, reinstated democracy, enjoyed a prolonged economic boom and, despite periods of sociopolitical turmoil became a developed country.
Today, Italy is considered to be one of the world's most culturally and economically advanced countries, with the sixth-largest worldwide national wealth. Its advanced economy ranks eighth-largest in the world and third in the Eurozone by nominal GDP. Italy owns the third-largest central bank gold reserve, it has a high level of human development, it stands among the top countries for life expectancy. The country plays a prominent role in regional and global economic, military and diplomatic affairs. Italy is a founding and leading member of the European Union and a member of numerous international institutions, including the UN, NATO, the OECD, the OSCE, the WTO, the G7, the G20, the Union for the Mediterranean, the Council of Europe, Uniting for Consensus, the Schengen Area and many more; as a reflection
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum; such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
The Vatican Observatory is an astronomical research and educational institution supported by the Holy See. Based in the Roman College of Rome, the Observatory is now headquartered in Castel Gandolfo and operates a telescope at the Mount Graham International Observatory in the United States; the Director of the Observatory is an American Jesuit. In 2008, the Templeton Prize was awarded to cosmologist Fr. Michał Heller, a Vatican Observatory Adjunct Scholar. In 2010, the George Van Biesbroeck Prize was awarded to former observatory director, the American Jesuit, Fr. George Coyne; the Church has had a long-standing interest in astronomy, due to the astronomical basis of the calendar by which holy days and Easter are determined. For instance, the Gregorian Calendar, promulgated in 1582 by Pope Gregory XIII, was developed by Aloysius Lilius and modified by Christoph Clavius at the Collegio Romano from astronomical data; the Gregorian Tower was completed in 1580 for his purpose, designed by Bolognese architect Ottaviano Matte.
In the 18th century, the Papacy supported astronomy, establishing the Observatory of the Roman College in 1774. In 1789–1787, the Specola Vaticana in the Tower of the Winds within the Vatican was established under the direction of Msgr. Filippo Luigi Gilii; when Msgr. Gilii died, the Specola was closed down because it was inconvenient for students in the city because the dome of St. Peter's obstructed its view, its instruments were transferred to the College Observatory. A third facility, the Observatory of the Capitol, was operated from 1827 to 1870. Father Angelo Secchi SJ relocated the College Observatory to the top of Sant'Ignazio di Loyola a Campo Marzio. In 1870, with the capture of Rome, the College Observatory fell into the hands of the Italian Government. Out of respect for his work, Father Secchi was permitted to continue using the Observatory. After Secchi's death in 1878 the Observatory was nationalized by the Italian government and renamed the Regio Osservatorio al Collegio Romano, ending astronomical research in the Vatican.
In 1891, Pope Leo XIII issued a Motu Proprio re-founding the Specola Vaticana and a new observatory was built on the walls at the edge of the Vatican. The new Vatican Observatory remained there for the next forty years. By the 1930s, the smoke and sky-glow of the city had made it impossible to conduct useful observations in Rome. Pope Pius XI relocated the Observatory to Castel Gandolfo, 25 kilometres southeast of Rome. By 1961, the same problems with light pollution made observing difficult at Castel Gandolfo; the Observatory established the Vatican Observatory Research Group, with offices at the Steward Observatory of the University of Arizona in Tucson, Arizona. D. K. J. O'Connell produced the first color photographs of a green flash at sunset in 1960. In 1993, VORG completed construction of the 1.8 metres Vatican Advanced Technology Telescope, at Mount Graham near Safford, Arizona. The Observatory's headquarters remain in Italy at Castel Gandolfo. In early 2008, the Vatican announced that the Observatory would be relocated to a former convent a mile away from the castle as part of a general reconstruction of the Papal residence.
Its former space would be used to provide more room for the reception of diplomatic visitors. There was some commentary that the Observatory was being shut down or cut back, but in fact the Observatory staff welcomed the move; the old quarters in the castle were cramped and poorly laid out for the Observatory's use. VORG research activities in Arizona continued unaffected. Archaeoastronomy Catholic Church and science#Vatican Observatory Guy Consolmagno Index of Vatican City-related articles Scientific Perspectives on Divine Action Vatican Advanced Technology Telescope Sabino Maffeo: The Vatican Observatory. In the Service of Nine Popes, Vatican Observatory Publications, 2001. Official website
Virtual International Authority File
The Virtual International Authority File is an international authority file. It is a joint project of several national libraries and operated by the Online Computer Library Center. Discussion about having a common international authority started in the late 1990s. After a series of failed attempts to come up with a unique common authority file, the new idea was to link existing national authorities; this would present all the benefits of a common file without requiring a large investment of time and expense in the process. The project was initiated by the US Library of Congress, the German National Library and the OCLC on August 6, 2003; the Bibliothèque nationale de France joined the project on October 5, 2007. The project transitioned to being a service of the OCLC on April 4, 2012; the aim is to link the national authority files to a single virtual authority file. In this file, identical records from the different data sets are linked together. A VIAF record receives a standard data number, contains the primary "see" and "see also" records from the original records, refers to the original authority records.
The data are available for research and data exchange and sharing. Reciprocal updating uses the Open Archives Initiative Protocol for Metadata Harvesting protocol; the file numbers are being added to Wikipedia biographical articles and are incorporated into Wikidata. VIAF's clustering algorithm is run every month; as more data are added from participating libraries, clusters of authority records may coalesce or split, leading to some fluctuation in the VIAF identifier of certain authority records. Authority control Faceted Application of Subject Terminology Integrated Authority File International Standard Authority Data Number International Standard Name Identifier Wikipedia's authority control template for articles Official website VIAF at OCLC
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics and chemistry in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, stars, nebulae and comets. More all phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject is physical cosmology, the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences; the early civilizations in recorded history, such as the Babylonians, Indians, Nubians, Chinese and many ancient indigenous peoples of the Americas, performed methodical observations of the night sky. Astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, but professional astronomy is now considered to be synonymous with astrophysics. Professional astronomy is split into theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, analyzed using basic principles of physics.
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain observational results and observations being used to confirm theoretical results. Astronomy is one of the few sciences in which amateurs still play an active role in the discovery and observation of transient events. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets. Astronomy means "law of the stars". Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now distinct. Both of the terms "astronomy" and "astrophysics" may be used to refer to the same subject. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties," while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, dynamic processes of celestial objects and phenomena."
In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could be called astrophysics; some fields, such as astrometry, are purely astronomy rather than astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics" depending on whether the department is affiliated with a physics department, many professional astronomers have physics rather than astronomy degrees; some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, Astronomy and Astrophysics. In early historic times, astronomy only consisted of the observation and predictions of the motions of objects visible to the naked eye.
In some locations, early cultures assembled massive artifacts that had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye; as civilizations developed, most notably in Mesopotamia, Persia, China and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, the nature of the Sun and the Earth in the Universe were explored philosophically; the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Ptolemaic system, named after Ptolemy.
A important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the astronomical traditions that developed in many other civilizations. The Babylonians discovered. Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, he proposed a model of the Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and inven