Did You Know About Astronomy.

Crab Nebula, a collection of supernova remnants. The image captured by the Hubble telescope.
Astronomy is a branch of natural science that involves the observation of celestial objects (such as stars, planets, comets, nebulae, star clusters, or galaxies) as well as natural phenomena that occur outside the Earth's atmosphere (such as the cosmic background radiation (CMB radiation) ). This is basic science study of the various celestial objects - such as the origin, nature physics / chemistry, meteorology, and motion - and how knowledge of these objects describes the formation and development of the universe.
Astronomy as a science is one of the oldest, as known from astronomical artifacts from the prehistoric era; eg monuments of Egypt and Nubia, or Stonehenge from Britain. The people of early civilizations sort of Babylon, Greece, China, India, and the Maya also found to have done the above methodological observations of the night sky. However, despite having a long history, astronomy could develop into a branch of modern science through the invention of the telescope.
Quite a lot of the branches of science that never are included as part of astronomy, and when observed, the nature of these branches are very diverse: from astrometry, space-based shipping, observational astronomy, to the preparation of the calendar and astrology. However, today's professional astronomy is considered synonymous with astrophysics.
In the 20th century, professional astronomy split into two branches: observational astronomy and theoretical astronomy. The first involves collecting data from observations of celestial objects, which will then be analyzed using basic principles of physics. The second focused on developing computer models / analytical to explain the properties of celestial objects and other natural phenomena. The second branch is complementary - theoretical astronomy seeks to explain the results of observational astronomical observations, and observational astronomy will then try to prove the conclusions made by the theoretical astronomy.
Amateur astronomers have been and continue to play an important role in many astronomical discoveries, making astronomy one of the few sciences where amateurs still maintains an active role, especially in the discovery and observation of transient phenomena.
Astronomy should be distinguished from astrology, which is the belief that human destiny and affairs relating to the location of celestial objects such as stars or rasinya. It is true that these two fields have the same origin, but at this point they are very different.

Lexicology. 

The word comes from the Greek astronomy, namely the words astron (ἄστρον, "star") is then given the suffix-nomy from nomos (νόμος, "law" or "culture"). So it literally means "law / culture of the stars".
The use of the term "astronomy" and "astrophysics".
In general good "astronomy" or "astrophysics" may be used to refer to the same science. If you are referring to the dictionary definitions of the standard, "astronomy" means "the study of celestial objects and matter outside the Earth's atmosphere as well as the physical properties and chemical material objects and the" moderate "astrophysics" is the branch of astronomy that dealing with "the behavior, physical properties, and dynamic processes of the objects and phenomena of the sky".
In certain cases, for example, at the opening of the book The Physical Universe by Frank Shu, "astronomy" may be used for the qualitative side of this science, being "astrophysics" to the other side which is more oriented physics. Nevertheless, modern astronomical studies mostly deal with topics related to physics, so that we may say that modern astronomy is astrophysics. Many bodies of research that, in deciding to use a term which, just depends on whether they are historically affiliated with the departments of physics or not. Professional astronomers themselves many have a degree in physics. For further illustration, one of the leading scientific journals in the disciplines of Astronomy and Astrophysics named (Astronomy and Astrophysics).

History. 

Space maps of the 17th century, the work of the Dutch cartographer Frederik de Wit.
At first, only involve astronomical observations along with the prediction of the movements of celestial objects visible to the naked eye. At some sites, such as Stonehenge, early civilizations also compiled artifacts are thought to have astronomical uses. This ancient observatory observatory aims plural ceremonial, but can also be used to determine the seasons, weather, and climate - something that must be known if you want to grow crops - or understand the long years.
Before the invention of equipment like telescopes, research must be done from the top of buildings or high plains, all with the naked eye. Along with the development of civilization, especially in Mesopotamia, China, Egypt, Greece, India, and Central America, the people started to build observatory and ideas on the nature of the universe began bustling examined. Generally, early astronomy preoccupied with mapping the location-location of the stars and planets (now called astrometry), activities that eventually led to theories about the movement of celestial objects and philosophical ideas to explain the origin of the Sun, Moon, and Earth. The earth was then regarded as the center of the universe, being the Sun, Moon, and stars revolve around it; model of this kind is known as the geocentric model or Ptolemaic system (from the name of the Roman-Egyptian astronomer Ptolemy).
Greek sun hours, from Ai-Khanoum (now in Afghanistan), 3-2 century BC.
Commencement astronomical calculations based on mathematical and scientific first pioneered by the Babylonians. They found that a lunar eclipse has a regular cycle, called saros cycle. Following the lead of the Babylonian astronomers, the progress for the progress achieved by the later Ancient Greek astronomy community and the surrounding countries. Greek astronomy from the outset was aimed to find a rational explanation for the physics-based and space phenomena. In the 3rd century BC, Aristarchus of Samos perform calculations of the size of the Earth and the distance between the Earth and the Moon, and then propose a heliocentric model of the solar system - the first time in history. In the 2nd century BC, Hipparchus discovered precession managed, also calculate the size of the Moon and the Sun and the distance between them, and make the research tools like the astrolabe astronomical earliest. The majority of the preparation of the constellations in the northern hemisphere it is still based on the composition of the formulated by him through a catalog which includes 1,020 of that time. Famous Antikythera Mechanism (ca. 150-80 BC) also from the same period: an analog computer used to calculate the location of the sun / moon / planets on a given date is the most complex item in history until the 14th century, when astronomical clocks began to appear in Europe.
In Europe alone during the Middle Ages astronomy was an impasse and stagnation. In contrast, the rapid development in the Islamic world and some other civilization, characterized by the construction of the observatory observatory in the world-there in the early 9th century. In 964, the Persian astronomer Al-Sufi find the Andromeda galaxy (galaxy largest in the Local Group) and recorded in the Book of Fixed Stars (Kitab al-Kawakib Suwar). Supernova SN 1006, the brightest star explosions in recorded history, was observed by the Egyptian astronomer Ali ibn Ridwan and the Chinese astronomers separate set of the same year (1006 AD). Astronomers of the Islamic era, mostly from Persian and Arabic, including Al-Battani, Thabit bin Qurrah, al-Sufi, Ibn Balkhi, al-Biruni, Al-Zarqali, Al-Birjandi, and astronomers of the observatory- observatory in Maragha and Samarkand. Through this era star whose names introduced by the Arabic language. Zimbabwe ruins in Britain and Timbuktu also likely to have had an observatory buildings - weakens the previous belief that there is no astronomical observation in sub-Saharan Africa prior to the colonial era.

Scientific revolution. 

Sketch of the Moon by Galileo. Through observation, it is known that the Moon's surface is hilly.
In the Renaissance, Copernicus' heliocentric model the solar system, a model which is then defended from controversy, developed, and corrected by Galileo and Kepler. Galileo's telescope to sharpen innovate with astronomical observations, Kepler was the first scientist who managed to be properly compiled and detailed movements of the planets with the Sun at the center. [28] However, he failed to formulate a theory to explain the laws which he wrote, to finally Newton (who also discovered the reflecting telescope for observations of the sky) to explain the dynamics through space and the laws of gravity.
Along with the improvements in the size and quality of the telescope, the more the further discoveries that happen. Through this technology successfully developed Lacaille catalogs of more complete; similar efforts undertaken by the German-British astronomer Herschel with producing catalogs of nebulae and clusters. In 1781 he discovered the planet Uranus, the first planet found outside the classical planets. Measurement of the distance to a star was first published in 1838 by Bessel, who at the time was to do it through parallax measurements of 61 Cygni.
18th century until the 19th century, first characterized by research on the three-body problem by Euler, Clairaut, and D'Alembert; research that results in a more precise prediction method for the movement of the Moon and the planets. This work was refined by Lagrange and Laplace, allowing scientists to estimate the masses of the planets and satellites through perturbation. The discovery of the spectroscope and photography then pushing the research further: in 1814-1815, Fraunhoffer discovered about 600 bands in the spectrum of the Sun, and in 1859 finally Kirchhoff could explain this phenomenon with the presence atribusiens elements. At this time the stars confirmed as the Sun-sun, another more far away, but with differences in temperature, mass, and size.
Only in the 20th century, the Milky Way (in which the Earth and the Sun is) can be proved as a group of separate from other star groups. From the same observations also concluded that there are other galaxies beyond the Milky Way and the universe continues to expand, because these galaxies continues to move away from our galaxy. Modern astronomy also found and tried to explain celestial objects such as quasars unfamiliar, pulsars, blazar, radio galaxies, black holes, and neutron stars. Physical cosmology advanced by leaps and bounds during this century: a model of the Big Bang (Big Bang), for example, has been supported by astronomical evidence and strong physics (among other CMB radiation, Hubble's law, and the availability of cosmological elements).

Observational astronomy. 

As is known, astronomers need information about celestial objects, and the most important source of information so far is electromagnetic radiation, or more specifically, the visible light. Observational astronomy can be divided according to regions of the electromagnetic spectrum observed: a portion of the spectrum can be observed through the Earth's surface, while other parts can only be reached from a certain height or even only from space. Detailed information about these divisions can be seen below:

Radio astronomy. 

This type of observational astronomy observing radiation with wavelengths greater than one millimeter (estimate). Unlike the other types, the type of observational astronomy observing radio waves that can be treated as a wave, not a discrete photons. Thus the measurement of phase and amplitude is relatively easy when compared to the shorter wavelength.
Radio waves can be generated by astronomical objects through thermal emission, but most of the radio emission observed from Earth is in the form of synchrotron radiation, which is produced when the electrons revolve around the magnetic field. A number of spectral lines produced by interstellar gas (eg hydrogen spectral line at 21 cm) can also be observed at radio wavelengths.
Some examples of objects that can be observed by radio astronomy: supernovae, interstellar gas, pulsars, and active galactic nuclei (AGN - active galactive nucleus).

Infrared astronomy. 

Infrared astronomy and its detection involves analysis of infrared radiation (wavelength radiation which exceeds the red light). Most of these types of radiation absorbed by the Earth's atmosphere, except where wavelengths do not differ too much with the red light appears. Therefore, the observatory is about to observe infrared radiation should be built in high places and not damp, or even in space.
This spectrum to observe objects that are too cold to emit visible light, for example, the planets or star discs. If the radiation has a wavelength tend to be longer, it can also help astronomers observe young stars in molecular clouds and galactic cores - because such radiation can penetrate the dust cover and obscure astronomical observations. Infrared astronomy can also be used to study the chemical structure of celestial bodies, as some molecules have a strong emission at this wavelength. One of its uses is to detect the presence of water in comets.

Optical astronomy. 

Subaru Telescope (left) and Keck Observatory (center) on Mauna Kea, both examples of observatories can observe both visible light or infrared light almost. On the right is the NASA Infrared Telescope Facility, which is only operating at near-infrared wavelengths.
Known also as visible light astronomy, optical astronomy observing electromagnetic radiation visible to the unaided human eye. Therefore, it is the oldest branch, because it requires no equipment. [38] Starting from the end of the 19th century until about a century later, images of astronomical optical wear photographic technique, but before that they should be drawn by hand . Today digital detectors are used, especially using a CCD (charge-coupled devices, device docked-charge).
Visible light is known as length of 4000 Å to 7000 Å (400-700 nm). Nevertheless, the observation tools used to observe the wavelength used as well as to observe the wave near-ultraviolet and near-infrared.

Ultraviolet astronomy. 

Namely ultraviolet electromagnetic radiation with a wavelength of approximately 100 to 3200 Å (10-320 nm). Lengths of light absorbed by the atmosphere as the Earth, so as to observe must be done from the upper atmosphere, or of outer atmosphere (outer space). Astronomy type is suitable for studying the thermal radiation and spectral emission lines of blue stars to extremely high temperature (classification OB), because such stars are very bright radiation ultraungunya - as is often done research and includes the stars located in other galaxies. In addition to the OB stars, celestial objects are often observed through this branch of astronomy include planetary nebulae, supernova remnants, or active galactic nuclei. Adjustment required for different purposes such as easy because the light is swallowed by interstellar dust.

X-ray astronomy. 

Objects may emit light wavelength of X-rays through synchrotron emission (derived from the electrons revolve around the magnetic field) or through thermal emission of concentrated and dilute gas of gas at 107 K.
X-rays are also absorbed by the atmosphere, so observations must be done from the top of the balloon, rocket, or satellite research. The sources of X-rays include X-ray binary star (X-ray binary), pulsars, supernova remnants, elliptical galaxies, clusters of galaxies, and active galactic nuclei.

Gamma-ray astronomy. 

Gamma-ray astronomy studying astronomical objects at the shortest wavelengths (gamma rays). Gamma rays can be observed directly by satellites such as the Compton Gamma-Ray Observatory (CGRO), or with a special type of telescope called Cherenkov telescopes (IACT).
It's actually kind of telescope does not detect gamma rays, but is able to detect the visible light produced spark from the absorption of gamma rays by the atmosphere.
Most gamma-ray source only in the form of gamma-ray bursts, which only produces the light in a matter of milliseconds to a few tens of seconds. Sources are not permanent and while only about 10% of the total number of sources, for example from the gamma-ray pulsars, neutron stars, or active galactic nuclei and black hole candidates.

The branches that are not based on wavelength. 

A number of other long-distance phenomena that shape other than electromagnetic radiation can be observed from Earth. There is a branch of astronomy called neutrinos, which astronomers use underground facilities (eg SAGE, GALLEX, or Kamioka II / III) to detect neutrinos, fundamental particles that form the plural derived from solar or supernova explosions. When cosmic rays enter the Earth's atmosphere, high-energy particles that compose it breaks down or absorbed, and a particle-particle decay products can be detected in the observatory.
In the future, it is expected there will be a neutrino detector is sensitive to particles that were born from the collision of cosmic rays and the atmosphere.
There is also a new branch using gravitational wave detectors to collect data about objects meeting: gravitational wave astronomy. Observatory-observatory for this field have started to be built, for example the LIGO observatories in Louisiana, USA. But such astronomical difficult, because the gravitational waves is very difficult to detect.
Planetary astronomy experts are also many who observe celestial phenomena directly, which rides through space and sample collection missions. Some only work with remote sensors to collect data, but several others involved with the landing-space vehicle capable of experimenting on the surface. Other methods eg detector immersed material or perform direct experiments on samples brought to Earth before.

Astrometry and celestial mechanics. 

The main article for this section are: Astrometry and celestial mechanics
Measurement location of celestial objects, as mentioned, is one of the branches of astronomy (and even science) the oldest. Activities such as shipping or preparation of the calendar is in desperate need of accurate knowledge of the location of the Sun, Moon, planets, and stars in the sky.
Of the measurement process like this produced an excellent understanding of gravitational perturbations and eventually astronomers can determine the position of celestial objects with the right in the past and the future - the branch of astronomy that go into this field known as celestial mechanics. Today the tracking on the objects close to the Earth also allows predictions will be a close encounter, or even collision.
Then there is a star parallax measurements. This measurement is very important because it gives the value of the base in the cosmic distance ladder method; through this method the size and scale of the universe can be known. Measurements of the relative parallax closer can also be used as a basis for absolute traits more distant stars, because the characteristics of them can be compared. Kinematics they then can be developed through the measurement of radial velocity and proper motion respectively. The results can also be used for astrometric measurements of dark matter in the galaxy.
During the 1990s, the technique of measuring the wobble of the astrometry used to detect the presence of planets outside the solar surrounds the stars near the Sun.

Theoretical astronomy. 

There are many types of methods and tools that can be utilized by a theoretical astronomer, among other analytical models (eg politrop to predict the behavior of a star) and computational numerical simulations, each with its own advantages. Analytical models are generally better if researchers want to know the specifics issues and observe what happens in outline; numerical models can reveal the existence of phenomena and effects that are not easily visible.
Theorists attempt to create theoretical models and concluded that the effects can be observed from these models. It will help the observer to know what data to look for to disprove a model, or decide which is true of alternative models to the contrary. Theorists also will try to draw up a new model or improve an existing model if no new data is entered. In the event of conflict / inconsistency, the tendency is to make minimal modifications to the model in question to accommodate the data that have been obtained. If the opposition too much, the model can be discarded and not used again.
Topics studied by theoretical astronomers include: dynamics and evolution of stars; formation of galaxies; Large-scale structure of matter in the universe, the origin of cosmic rays; general relativity, and cosmology physical (including string cosmology and physics astropartikel) . Astrophysical relativity is used to measure the characteristics of large-scale structures, where there is a major role of the force of gravity; well as the basis of the physics of black holes and gravitational wave research.
Some models / theories that have been widely accepted and studied the theory of the big bang, cosmic inflation, dark matter, and fundamental theories of physics. This group of models and theories have been integrated in the Lambda-CDM models.

Some examples of the process: 

Physical process of experiment Tool The theoretical model described / predicted
Gravity radio telescope Nordtvedt Effect (self-gravity system) The Birth of a star system
Evolution of nuclear fusion Spectroscopy How incandescent star, how metal is formed (nucleosynthesis).
Big Bang (Big Bang) Hubble Space Telescope, COBE Age universe expanding universe
The problem of quantum fluctuations of cosmic inflation of the universe flatness (flatness problem)
Gravitational collapse of X-ray Astronomy A set of general relativity black hole at the center of the Andromeda Galaxy.
CNO cycle in stars
Discourse that was warm in astronomy in recent years is the dark matter and dark energy - the discovery and controversy regarding these topics stems from the study of galaxies.

Specific branches. 

Solar astronomy. 

Active ultraviolet image of the Sun's photosphere, the catch by NASA's TRACE telescope.
The sun is the nearest star from Earth in about 8 minutes of light, and the most frequently researched: it is a dwarf on the main sequence G2 classification V and about 4.6 billion years old. Although not up to the level of the variable star, the Sun is a slight change of light through the activity known as the sunspot cycle - fluctuations in the number of spots sun for eleven years. Sun spots are areas with lower temperatures and intense magnetic activity.
Sun's luminosity is still growing strong throughout his life, and since the first time on the main sequence has been increased by 40%. The sun also has recorded periodic changes in luminosity, something which could lead to significant consequences to life on Earth. For example, the period of the Maunder minimum, which is to cause the phenomenon of the little ice age in the Middle Ages.
Outer surface of the sun that we can see is called the photosphere. On it there is a thin layer that is normally not visible due to the brightness of the photosphere, the chromosphere. Above that there is a transition layer where the temperature can rise quickly, and in it lies the very hot corona.
In the center of the Sun is the core region; existing levels of temperature and pressure sufficient here so that nuclear fusion can occur. On it there is a radiative zone; plasma here will dissipate heat through radiation process. At the top of the radiative zone is the convective zone; material gas in this zone will energy dissipates most of the movement of material through the gas itself. This zone is believed to be the source of the magnetic activity of the Sun producing spots.
There is a form of solar wind plasma particles blowing out from the Sun continuously until it reaches the point of the heliopause. The wind is met with the Earth's magnetosphere and radiation belts form the Van Allen and - in which the magnetic field lines of the Earth's atmosphere to down - produce the aurora.

Planetary science. 

This branch of astronomy examines the composition of planets, moons, dwarf planets, comets, asteroids, and other celestial objects that surround stars, especially the Sun, although this science also includes the outer solar planets. Our own solar system has been studied in depth - first of all through the telescope and then use the vehicles of space - so the current understanding of the formation and evolution of planetary systems is already very good, although there are still new discoveries are happening.
Black dot on top is a vicious dust (dust devil) who was climbing a crater on Mars. It is similar to a tornado that twisted and moved, resulting in "tails" are long and dark. Image by NASA.
Solar System is divided into several groups: the inner planets, the asteroid belt, and the outer planets. Inner planets are terrestrial planets which are Mercury, Venus, Earth and Mars. The outer planets are gas giants of the solar system are Jupiter, Saturn, Uranus, and Neptune. If we go further, it will be found objects trans-Neptunian: first Kuiper belt and the Oort cloud could eventually stretched to a light year.
The formation of the planets originated in a protoplanetary disc around the Sun that in the initial periods. Realization of this disc clumps of matter through a process involving the pull of gravity, collision, and accretion; these clumps then gradually becoming protoplanetary collection. Because the radiation pressure of the solar wind continues to push the materials that have not clot, only planets whose mass is large enough that is able to maintain a gaseous atmosphere. The planets continued to sweep this young and spew the remaining material, produces a period of great destruction. Remnants of this period can be seen through the many craters on the lunar surface collisions. As in this period the majority of the protoplanet-protoplanet that there may collide with one another; likely collision as that which gave birth to our moon.
When a planet reaches a certain mass, the materials with different densities begin to separate from one another in a process called planetary differentiation. Such a process could produce rocky core or materials composed of metal, covered by a layer of the mantle and the outer surface. The core of the planet can be divided into areas of solid and liquid, and some are able to produce their own magnetic field, so that the planet can be protected from the solar wind.
The heat in the interior of a planet or moon comes from the collisions that produced solely by planet / month, or by radioactive materials (eg uranium, thorium, or 26Al), or tidal heating. Some planets and moons managed to collect enough heat to drive geologic processes such as volcanism and tectonic activities. If the planet / moon also has an atmosphere, the erosion of the surface (through wind or water) can also occur. Planet / moon smaller and without tidal heating would be cool faster and geological activities will come to an end, with the exception of the formation of craters collision.

Astronomy star. 

Ant Nebula. Gas spewed from a dying star at its center is unusual because it forms a symmetrical pattern, not chaotic like an explosion in general.
To understand the universe, the study of the stars and how they evolve is fundamental. Astrophysics with respect to the stars themselves can be known either through observation terms and theoretical terms, as well as through computer simulation.
Stars form in giant molecular clouds, which are dense regions of dust and gas will. When it loses its stability, fragments of these clouds can collapse under the force of gravity to form a protostar. If part of the point reaches a certain density and temperature, nuclear fusion will be triggered and will form a main sequence star.
Almost all elements heavier than hydrogen and helium are the result of processes that occur in the core of stars.
The characteristics that will be owned by the outline of a star is determined by the initial mass : the greater the mass , the higher the luminositasnya , and the sooner he will spend the hydrogen fuel in the core . Gradually , the hydrogen fuel is converted into helium , and the star in question will begin to evolve . To perform the fusion of helium requires a higher core temperature , so it will be more solid core and double the size of any star - the star has become a red giant . Red giant phase is relatively short , until the helium fuel also is used up . If the star has a very large mass , it will begin the phases of evolution where it has narrowed gradually , since resorted to nuclear fusion of the elements heavier .
As for the final fate of a star depends also on the mass . If the mass is more than about eight times our sun , the gravitational core will collapse and produce a supernova , otherwise , would be a planetary nebula , and continues to evolve into a white dwarf . What remains after a supernova eruption is a very dense neutron star , or , if the matter rest three times the mass of the Sun , a black hole . Binary stars that are close together can be more complicated evolution , for example , can occur in the direction of mass transfer his star that can cause a supernova .
Planetary nebulae and supernovas required to process the distribution of metals in the interstellar medium , otherwise Thus, all new stars ( and their planetary systems ) would be composed only of hydrogen and helium alone .

Galactic astronomy .

The structure of the spiral arms of the Milky Way that has been observed .
Circulating in our Solar System in the Milky Way , a barred spiral galaxy in the Local Group . He is one of the most prominent in the galaxy group . Milky Way rotate material gas , dust , stars, and other objects , all gathered together due to gravitational pull . Earth itself is located on a dusty galaxy arm that is on the outside , so a lot of areas that are not visible Milky Way .
At the center is the core of the galaxy , sort of like a rod -shaped protrusions ; believed that there is a supermassive black hole at the center of this . This section is surrounded by four primary arms that circle from the center toward the outside , and it is rich in phenomena of star formation , so it contains many young stars
( metalisitas population I). The disc is then covered by a ring galaxy contains stars that are older ( metalisitas population II ) and also clusters of spherical
(globular) , which is a kind of star clusters are relatively more dense .
The area between the stars is called the interstellar medium , ie areas containing rare material - parts are relatively populous molecular clouds containing hydrogen and other elements , a place where many new stars will be born . Will initially formed a core of pre - docked or dark nebula and then collapse ( in volumes determined by the Jeans length ) to build a protostar .
While many big stars who appeared , they will transform into a cloud of molecular clouds H II regions , namely cloud with incandescent gas and plasma . In the end the wind and supernova explosions from these stars will disperse the remaining clouds , usually results in a ( or more than one ) new open star clusters . These clusters gradually glow , and the stars join the Milky Way .
Numerous studies kinematics with respect to the materials in the Milky Way ( and other galaxies ) indicate that the material that looks mass less than the mass of the entire galaxy . This indicates there is a so-called dark matter that is responsible for most of the overall mass , but many things are still unknown about this mysterious material .

Extragalactic astronomy .

The image above displays some circular blue object ; these are images of the same galaxy , by gravitational lens effect caused by a cluster of yellow galaxies at the center of the photograph . The lens effect generated clusters and gravitational fields bend light so that an image one object further magnified and distorted .
The study objects that are outside our galaxy - extragalactic astronomy - a branch that studies the formation and evolution of galaxies , their morphology and classification , as well as observations of active galaxies and their groups and clusters of galaxies . This , especially the latter , it is important to understand the structure of the universe on a large scale .
Most galaxies will form certain beings , so that the classification can be prepared based on these beings . Usually , they are divided into spiral galaxies , elliptical , and irregular .
Just like the name suggests , an elliptical galaxy is shaped like an ellipse . The stars revolve pata random orbit without a clear direction towards . These galaxies like dust content very little or none; producing region is not much the star , and the average occupant of the stars of old . Elliptical galaxies are usually found in the core of a galaxy cluster , and can be born through the fusion of large galaxies .
Forming spiral galaxies rotating flat disc , usually with a bulge or bar at the center of the spiral arms and bright arising from the passage. These arms are dusty field where the birth of new stars , and its inhabitants are young stars that have masses large and glowing blue . Generally , the spiral galaxy surrounded by a ring composed of stars that are older . Examples of this kind of galaxy is the Milky Way and Andromeda .
The galaxies are chaotic and irregular shape does not resemble a particular wake like a spiral or an elliptical . Roughly one quarter of the galaxies classified as irregular , probably caused by the gravitational interaction .
A galaxy is said to be active if it emits a significant amount of energy from sources other than the stars , dust , or gas ; too , if the power source comes from the dense area around the nucleus - the possibility of a supermassive black hole that emits radiation of objects that he swallowed .
If an active galactic radiation radio spectrum has a very bright and emit large amounts of gas because , the galaxy is classified as a radio galaxy . Examples of such galaxies are Seyfert galaxies , quasars , and blazar . Quasar is now believed to be the most certainly very bright , never found specimens dim .
Large -scale structure of the universe is now described as a collection of groups and clusters of galaxies . This structure is further classified in a hierarchy of groupings ; biggest is maha - cluster ( a supercluster ) . Then these groups are arranged into filaments and walls of galaxies , with nothing in between them .

Cosmology .

Cosmology , from the Greek word cosmos ( κόσμος , " world " ) and the suffix - logia of logos ( λόγος , " study " ) can be understood as an effort to examine the universe as a whole .
Observations of large -scale structure of the universe , a branch known as physical cosmology , has donated a thorough understanding of the formation and evolution of the universe . One of the most important theories ( and widely accepted ) is the Big Bang theory , which states that the world begins at one point and expands over 13.7 billion years up to the present .
This idea can be traced back to the discovery of the microwave background radiation cosmic in 1965 .
During the development process , nature has undergone some degree of evolution . At first , it is suspected that there is a very rapid cosmic inflation , resulting in homogenization of the initial conditions . After it through nucleosynthesis resulting availability of the elements for the early period of the universe .
When the first popping atoms , space became transparent to radiation , releasing the energy that is now known as the CMB radiation . Universe was expanding into the middle of the Dark Ages , because there is no source of power that can emit light .
A hierarchical structure of matter began to form through small variations in density.
The material then accumulated in the regions with the highest density , spawned clouds of gas and stars are the most ancient ( metalisitas III ) . These massive stars triggered the reionization and is believed to have created many of the heavy elements in the early universe ; these elements tend to decay back into the elements lighter extending the cycle .
The collection is triggered by gravity resulting in material form filaments and leaving empty spaces in between . Gradually , the gas and dust merged to form the primitive galaxies . Over time more and more material is withdrawn , and is organized into groups and clusters of galaxies . In the end , maha - larger clusters was realized .
Other objects that play an important role in the structure of the universe is dark matter and dark energy . These objects which turned out to be a major component of our world , where their mass reaches 96 % of the total mass of the universe . Therefore , efforts are made ​​to examine and understand the terms of the physics of these objects .

Interdisciplinary studies .

Astronomy and astrophysics has floated a strong relationship with the branches of other sciences . Arkeoastronomi For example , the study of ancient or traditional astronomy in the context of their respective cultures using archaeological evidence and anthropological . Or astrobiology , this time studying the birth and development of biological systems in the universe, particularly on the topic of life on other planets .
There is also a branch that examines the chemicals found in space , how they manifest , behave , and indestructible . This is called astrokimia . Substances to be studied is usually found in molecular clouds , although there are also contained in the low -temperature stars , brown dwarf , or planet . Then kosmokimia , similar science research leads to the elements and isotope ratio variations in the Solar System . These sciences can describe the intersection of the sciences of astronomy and chemistry . Even now there are forensic astronomy , where astronomical methods used to solve the problems of law and history .

Amateur astronomy .

Amateur astronomers can build their own equipment and organize parties and meetings astronomy , for example Stellafane community .
As mentioned , astronomy is one of the few branches of science where amateurs can contribute a lot . Overall, amateur astronomers observe a variety of celestial objects and phenomena , sometimes even with the equipment that they make themselves . The plural is observed that the Moon , planets, stars , comets , meteor showers , and objects in the sky such as star clusters, galaxies , and nebulae . One branch of amateur astronomy is amateur astrophotography , which involves retrieval photographs of the night sky . Many choose to be astrofotografer that spesialis in certain objects or events .
Most amateur astronomers working in optical astronomy , although there is also a small part to experiment with wavelengths outside the visible light , for example with infrared filters on conventional telescopes or use radio telescopes . Pioneer of amateur radio astronomy was Karl Jansky , who started this event in the 1930s . Amateur Jansky 's kind of like wearing a homemade telescope or professional radio telescopes now be accessible to the amateur as well as the One Mile Telescope ( One - Mile Telescope ) .
Contribution of amateur astronomers are not trivial , because a lot of things - like taking the measurements of the occultation in order to sharpen records planets orbit small - rely on the work of amateur astronomy . The amateur can also find a comet or doing routine research over variable stars . Along with the development of digital technology , amateur astrophotography is also more effective and even more to contribute knowledge .

List of unsolved problems of astronomy .

Although the science of astronomy has experienced progress very rapidly and make the breakthroughs that are very large in an effort to understand the universe and everything in it , there are still some important questions yet to be answered . To solve such problems , may require building new equipment in both the surface of the Earth and in space . Moreover, it may also be required of new developments in theoretical and experimental physics .
Is the origin of the stellar mass spectrum ? That is , why do astronomers continue to observe the same mass distribution - that is , the same initial mass function - although the initial establishment of the state of the stars vary ?
Required a deeper understanding of the formation of stars and planets .
Are there any other life form in the universe ? Is there any form of intelligent life elsewhere in the universe ? If there is , what is the answer to the Fermi paradox ? If there is life outside of Earth, its implications, both scientific and philosophical , is very important .  Are we including the Solar System normal or unusual turns ?
What caused the formation of the universe ? Is the premise underlying the hypothesis " that the universe is well tuned " ( fine-tuned universe ) right ? If appropriate , if there is such a large-scale cosmological natural selection ? What exactly causes early cosmic inflation , so nature becomes homogeneous ? Why there is a baryon asymmetry in the universe ?
What is the true nature of dark matter and dark energy ? They have dominated the development process and , ultimately , the fate of the universe , but their fundamental properties still have not understood .
 What will happen in the end times ?
How the first galaxies formed ? How supermassive black holes form ?
What produces energy cosmic rays ultra-high?
So, thank you for reading this article . Written and posted by Bambang Sunarno.
sunarnobambang86@gmail.com
author:
http://schema.org/Personal.
https://plus.google.com/105319704331231770941.
name: Bambang Sunarno.
http://primadonablog.blogspot.com/2014/02/did-you-know-about-astronomy.html
DatePublished: February 14, 2014 at 22:12

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Tag : Astronomy.