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47-647: The Fourcade-Figueroa Object was discovered in May 1970, by two astronomers , Carlos Raúl Fourcade from Argentina and Egardo Javier Figueroa from Chile while capturing the Centaurus A region with a Curtis-Schmidt camera at Cerro Tololo Inter-American Observatory . This discovery prompted both Fourcade and Figueroa to name the object after themselves. For seven years, the Fourcade-Figueroa Object appears to be diffused and elongated. According to Dottori and Fourcade, it

94-429: A dimensions of 17 x 2 arcmin. It has an inclination angle between 86 and 90 degrees and is surrounded by a cloud of neutral hydrogen , that is dissolving its mass by 5%. The Fourcade-Figueroa Object is classified as a proto-typical superthin galaxy. When observed at both optical and HI wavelengths , the object is disrupted when seen towards the northwest side. It is also known to have its thickness of gas showing

141-484: A magnetosphere around a planet. Early space probes discovered the gross dimensions of the terrestrial magnetic field, which extends about 10 Earth radii towards the Sun. The solar wind , a stream of charged particles, streams out and around the terrestrial magnetic field, and continues behind the magnetic tail, hundreds of Earth radii downstream. Inside the magnetosphere, there are relatively dense regions of solar wind particles,

188-450: 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 highly ambitious people who own science-grade telescopes and instruments with which they are able to make their own discoveries, create astrophotographs , and assist professional astronomers in research. Planetary science Planetary science (or more rarely, planetology )

235-438: 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 also have outreach programs, including public telescope time and sometimes planetariums , as a public service to encourage interest in

282-404: A galaxy shredding process with Centaurus A. As a result, a dwarf elliptical galaxy , NGC 5237 , is created from its core while the rest of the galaxy's material became the object, it is known today. The Fourcade-Figueroa Object is found to be large with knots of resolved stars extending along the major axis by a distance of 15 arc minutes. According to Holmberg, the Fourcade-Figueroa Object has

329-415: A mountain as tall as, for example, 15 km (9 mi), would develop so much pressure at its base, due to gravity, that the rock there would become plastic , and the mountain would slump back to a height of roughly 10 km (6 mi) in a geologically insignificant time. Some or all of these geologic principles can be applied to other planets besides Earth. For instance on Mars, whose surface gravity

376-489: A smooth and polished surface" suggested that it and other worlds might appear "just like the face of the Earth itself". Advances in telescope construction and instrumental resolution gradually allowed increased identification of the atmospheric as well as surface details of the planets. The Moon was initially the most heavily studied, due to its proximity to the Earth, as it always exhibited elaborate features on its surface, and

423-439: A specific question or field outside the scope of Earth . Astronomers observe astronomical objects , such as stars , planets , moons , comets and galaxies – in either observational (by analyzing the data) 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 . A related but distinct subject

470-471: A steep gas flare in agreement with the stellar disk edge. Based on the Navarro-Frenk-White dark matter distribution and a pseudo-isothermal halo models, the Fourcade-Figueroa Object contains a compact core of dark matter . This indicates the reason why the galaxy has a superthin stellar disk structure. Astronomer An astronomer is a scientist in the field of astronomy who focuses on

517-456: A strongly interdisciplinary field, which originally grew from astronomy and Earth science , and now incorporates many disciplines, including planetary geology , cosmochemistry , atmospheric science , physics , oceanography , hydrology , theoretical planetary science , glaciology , and exoplanetology . Allied disciplines include space physics , when concerned with the effects of the Sun on

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564-738: 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, evolve, and die. They use this 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 , astrobiology , stellar astronomy , astrometry , galactic astronomy , extragalactic astronomy , or physical cosmology . Astronomers can also specialize in certain specialties of observational astronomy, such as infrared astronomy , neutrino astronomy , x-ray astronomy , and gravitational-wave astronomy . Historically , astronomy

611-555: A wide range of peer reviewed journals . Some planetary scientists work at private research centres and often initiate partnership research tasks. The history of planetary science may be said to have begun with the Ancient Greek philosopher Democritus , who is reported by Hippolytus as saying The ordered worlds are boundless and differ in size, and that in some there is neither sun nor moon, but that in others, both are greater than with us, and yet with others more in number. And that

658-462: Is physical cosmology , which studies the Universe as a whole. Astronomers usually fall under either of two main types: observational and theoretical . Observational astronomers make direct observations of celestial objects and 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

705-642: Is an important transitional zone between the solid planetary surface and the higher rarefied ionizing and radiation belts. Not all planets have atmospheres: their existence depends on the mass of the planet, and the planet's distance from the Sun ;– too distant and frozen atmospheres occur. Besides the four giant planets , three of the four terrestrial planets ( Earth , Venus , and Mars ) have significant atmospheres. Two moons have significant atmospheres: Saturn 's moon Titan and Neptune 's moon Triton . A tenuous atmosphere exists around Mercury . The effects of

752-497: Is much less, the largest volcano, Olympus Mons , is 27 km (17 mi) high at its peak, a height that could not be maintained on Earth. The Earth geoid is essentially the figure of the Earth abstracted from its topographic features. Therefore, the Mars geoid ( areoid ) is essentially the figure of Mars abstracted from its topographic features. Surveying and mapping are two important fields of application of geodesy. An atmosphere

799-488: Is said to be associated with Centaurus A as a shred . In the year 1978, Graham reached a conclusion and found the object is a late-type galaxy. In the Second Reference Catalogue, the Fourcade-Figueroa Object has been catalogued as A 1332–45. It is very faint to observe, even using an amateur telescope . The Fourcade-Figueroa Object seems to be a stellar remanent caused by a progenitor spiral galaxy undergoing

846-454: Is the scientific study of planets (including Earth ), celestial bodies (such as moons , asteroids , comets ) and planetary systems (in particular those of the Solar System ) and the processes of their formation. It studies objects ranging in size from micrometeoroids to gas giants , with the aim of determining their composition, dynamics, formation, interrelations and history. It is

893-641: The Apollo astronauts for the field geology they would encounter on their lunar missions. Overlapping sequences were identified on images taken by the Lunar Orbiter program , and these were used to prepare a lunar stratigraphic column and geological map of the Moon. One of the main problems when generating hypotheses on the formation and evolution of objects in the Solar System is the lack of samples that can be analyzed in

940-498: The HED meteorites back to a specific asteroid in the main belt, 4 Vesta . The comparatively few known Martian meteorites have provided insight into the geochemical composition of the Martian crust, although the unavoidable lack of information about their points of origin on the diverse Martian surface has meant that they do not provide more detailed constraints on theories of the evolution of

987-647: The Van Allen radiation belts . Planetary geophysics includes, but is not limited to, seismology and tectonophysics , geophysical fluid dynamics , mineral physics , geodynamics , mathematical geophysics , and geophysical surveying . Planetary geodesy (also known as planetary geodetics) deals with the measurement and representation of the planets of the Solar System, their gravitational fields and geodynamic phenomena ( polar motion in three-dimensional, time-varying space). The science of geodesy has elements of both astrophysics and planetary sciences. The shape of

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1034-436: The biosphere , but those meteorites collected in the last few decades from Antarctica are almost entirely pristine. The different types of meteorites that originate from the asteroid belt cover almost all parts of the structure of differentiated bodies: meteorites even exist that come from the core-mantle boundary ( pallasites ). The combination of geochemistry and observational astronomy has also made it possible to trace

1081-451: The gravity fields of the planets to be mapped. For example, in the 1970s, the gravity field disturbances above lunar maria were measured through lunar orbiters, which led to the discovery of concentrations of mass, mascons , beneath the Imbrium, Serenitatis, Crisium, Nectaris and Humorum basins. If a planet's magnetic field is sufficiently strong, its interaction with the solar wind forms

1128-399: The rotation rate of a planet about its axis can be seen in atmospheric streams and currents. Seen from space, these features show as bands and eddies in the cloud system and are particularly visible on Jupiter and Saturn. Exoplanetology studies exoplanets , the planets existing outside our Solar System . Until recently, the means of studying exoplanets have been extremely limited, but with

1175-469: The Earth is to a large extent the result of its rotation, which causes its equatorial bulge , and the competition of geologic processes such as the collision of plates and of vulcanism , resisted by the Earth's gravity field. These principles can be applied to the solid surface of Earth ( orogeny ; Few mountains are higher than 10 km (6 mi), few deep sea trenches deeper than that because quite simply,

1222-506: The Martian lithosphere . As of July 24, 2013, 65 samples of Martian meteorites have been discovered on Earth. Many were found in either Antarctica or the Sahara Desert. During the Apollo era, in the Apollo program , 384 kilograms of lunar samples were collected and transported to the Earth, and three Soviet Luna robots also delivered regolith samples from the Moon. These samples provide

1269-532: The Middle East. The total mass of recognized lunar meteorites is close to 50 kg. Space probes made it possible to collect data in not only the visible light region but in other areas of the electromagnetic spectrum. The planets can be characterized by their force fields: gravity and their magnetic fields, which are studied through geophysics and space physics. Measuring the changes in acceleration experienced by spacecraft as they orbit has allowed fine details of

1316-542: The PhD level and beyond (as of 2024). 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 (CCD) 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 relatively little time at telescopes, usually just

1363-475: The Solar System and extrasolar planetary systems. Observing exoplanets and determining their physical properties, exoplanetology , is a major area of research besides Solar System studies. Every planet has its own branch. In planetary science, the term geology is used in its broadest sense, to mean the study of the surface and interior parts of planets and moons, from their core to their magnetosphere. The best-known research topics of planetary geology deal with

1410-408: The Sun, or the geomorphology of the surfaces of the terrestrial planets, to give only a few examples. The main comparison that can be made is to features on the Earth, as it is much more accessible and allows a much greater range of measurements to be made. Earth analog studies are particularly common in planetary geology, geomorphology, and also in atmospheric science. The use of terrestrial analogs

1457-425: The astronomy and physics or Earth sciences departments of universities or research centres, though there are several purely planetary science institutes worldwide. Generally, planetary scientists study one of the Earth sciences , astronomy , astrophysics , geophysics , or physics at the graduate level and concentrate their research in planetary science disciplines. There are several major conferences each year, and

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1504-550: The bodies of the Solar System, and astrobiology . There are interrelated observational and theoretical branches of planetary science. Observational research can involve combinations of space exploration , predominantly with robotic spacecraft missions using remote sensing , and comparative, experimental work in Earth-based laboratories . The theoretical component involves considerable computer simulation and mathematical modelling . Planetary scientists are generally located in

1551-421: The core sciences, a competency examination, experience with teaching undergraduates and participating in outreach programs, work on research projects under the student's supervising professor, completion of a PhD thesis , and passing a final oral exam . Throughout the PhD training, a successful student is financially supported with a stipend . While there is a relatively low number of professional astronomers,

1598-410: The current rate of innovation in research technology , exoplanetology has become a rapidly developing subfield of astronomy . Planetary science frequently makes use of the method of comparison to give a greater understanding of the object of study. This can involve comparing the dense atmospheres of Earth and Saturn's moon Titan , the evolution of outer Solar System objects at different distances from

1645-472: The features on planetary surfaces and reconstructs the history of their formation, inferring the physical processes that acted on the surface. Planetary geomorphology includes the study of several classes of surface features: The history of a planetary surface can be deciphered by mapping features from top to bottom according to their deposition sequence , as first determined on terrestrial strata by Nicolas Steno . For example, stratigraphic mapping prepared

1692-469: The field is popular among amateurs . Most cities have amateur astronomy clubs that meet on a regular basis and often 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. As with any hobby , most people who practice amateur astronomy may devote

1739-489: The field. Those who become astronomers usually have a broad background in physics, mathematics , sciences, and computing in high school. Taking courses that teach how to research, write, and present papers are part of the higher education of an astronomer, while most astronomers attain both a Master's degree and eventually a PhD degree in astronomy, physics or astrophysics . PhD training typically involves 5-6 years of study, including completion of upper-level courses in

1786-408: The intervals between the ordered worlds are unequal, here more and there less, and that some increase, others flourish and others decay, and here they come into being and there they are eclipsed. But that they are destroyed by colliding with one another. And that some ordered worlds are bare of animals and plants and all water. In more modern times, planetary science began in astronomy, from studies of

1833-403: The laboratory, where a large suite of tools are available, and the full body of knowledge derived from terrestrial geology can be brought to bear. Direct samples from the Moon, asteroids and Mars are present on Earth, removed from their parent bodies, and delivered as meteorites . Some of these have suffered contamination from the oxidising effect of Earth's atmosphere and the infiltration of

1880-687: The majority of their time working on research, although they quite often have other duties such as teaching, building instruments, or aiding in the operation of an observatory. The American Astronomical Society , which is the major organization of professional astronomers in North America , has approximately 8,200 members (as of 2024). This number includes scientists from other fields such as physics, geology , and engineering , whose research interests are closely related to astronomy. The International Astronomical Union comprises about 12,700 members from 92 countries who are involved in astronomical research at

1927-615: The most comprehensive record of the composition of any Solar System body besides the Earth. The numbers of lunar meteorites are growing quickly in the last few years – as of April 2008 there are 54 meteorites that have been officially classified as lunar. Eleven of these are from the US Antarctic meteorite collection, 6 are from the Japanese Antarctic meteorite collection and the other 37 are from hot desert localities in Africa, Australia, and

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1974-559: The planetary bodies in the near vicinity of the Earth: the Moon , and the two neighboring planets: Venus and Mars . Of these, the Moon was studied first, using methods developed earlier on the Earth. Planetary geology focuses on celestial objects that exhibit a solid surface or have significant solid physical states as part of their structure. Planetary geology applies geology , geophysics and geochemistry to planetary bodies. Geomorphology studies

2021-467: The rate of new discoveries is very high, partly due to the large number of interplanetary spacecraft currently exploring the Solar System. Planetary science studies observational and theoretical astronomy, geology ( astrogeology ), atmospheric science , and an emerging subspecialty in planetary oceans , called planetary oceanography . This is both an observational and a theoretical science. Observational researchers are predominantly concerned with

2068-474: The study of the small bodies of the Solar System: those that are observed by telescopes, both optical and radio, so that characteristics of these bodies such as shape, spin, surface materials and weathering are determined, and the history of their formation and evolution can be understood. Theoretical planetary astronomy is concerned with dynamics : the application of the principles of celestial mechanics to

2115-495: The technological improvements gradually produced more detailed lunar geological knowledge. In this scientific process, the main instruments were astronomical optical telescopes (and later radio telescopes ) and finally robotic exploratory spacecraft , such as space probes . The Solar System has now been relatively well-studied, and a good overall understanding of the formation and evolution of this planetary system exists. However, there are large numbers of unsolved questions, and

2162-409: The unresolved planets. In this sense, the original planetary astronomer would be Galileo , who discovered the four largest moons of Jupiter , the mountains on the Moon , and first observed the rings of Saturn , all objects of intense later study. Galileo's study of the lunar mountains in 1609 also began the study of extraterrestrial landscapes: his observation "that the Moon certainly does not possess

2209-498: 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 mostly disappeared and the terms "astronomer" and "astrophysicist" are interchangeable. Professional astronomers are highly educated individuals who typically have a PhD in physics or astronomy and are employed by research institutions or universities. They spend

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