What is An Observatory?

An observatory is called as the place where celestial observations are made and celestial bodies and phenomena are examined. Formerly named as “rasathane” in Turkish, observatories are research centers equipped with sophisticated devices and examining the universe more and more in depth through greatly taking the advantage of developments in the fields of optics, physics, chemistry and electronics.

The situation was very different from today’s advanced observatories when compared to past. There were not observation tools for those people who dedicated themselves to the examination of the sky in ancient times. Their only basis was their eyes.

Observation Homes were usually ordinary buildings built in quiet and high places. Ancient astronomers used to observe the sun, stars and movements of the planets from these centers through the aid of some reference points. These reference points were large monuments like pyramids in Egypt or stones illuminated by the Sun on certain periods of the year.( For instance, the ruins of the observation homes which remained from Inca in Central America and Mayans confirm this notion)


What is a Telescope?

 

A telescope is an observatory instrument which takes and displays all kinds of radiation coming from space and is used by astronomers. All kinds of electromagnetic transmissions such as visible lights, ultraviolet rays, infrared rays, X-rays, radio waves reflecting from the objects in space or coming directly from them are necessary evidences to gather information about the universe. Optical properties of mirrors and lenses were known long ago by Islamic scholars. The first description of the shape of the telescope was made by the Turkish Islamic scholar Abu’l-Hasan. [971-1029 (H.360-420)]. Abu’l-Hasan described telescope as a pipe which has lenses (lenses) in its ends. Islamic scholars have numerous studies on this subject and thus science of astronomy highly developed. But Galileo was able to introduce telescope to Europe in 1609.

Structurally, telescope consists of a lens, ocular and  tube which maintains these lenses. There are two types of telescope according to the types of lens. If lights coming from space bounce off a mirror in the telescope and come to the eye after passing through the prism, this species is called reflective telescope. If lights coming from space come directly to the eye passing through the lenses, this species is called as the refracting telescope.

The power of telescope is proportional to the amount of light it collects. When the objective diameter grows, its light-gathering ability increases. For instance, when compared, a telescope 5cm in diameter gathers 2 or 100 times more ligth than its pupil 0,5 cm in diameter. This amount reduces by ten per cent as there may be reflection losses in the telescopes. Astronomers describe the differences in brightness as logarithmically increasing values. 100-fold difference in brightness is seen as the value of 5 in the scale of telescope. The light intensity of human eye can see 5 valuable stars. The lens diameter of the Hale Telescope on Mount Palomar in California is 5 meters. This telescope collects a million times light when compared to the eye.


The sharpness of the image formed in the telescope vary depending on negative effect of the atmosphere. The stability in telescope is valid for 2 arc seconds. Atmospheric conditions reduces this angle as much as 0.25 arc seconds. In this instance, not the images of the star which was examined but the images of surrounding stars are saved.

 

What is Astronomy?

Astronomy is a branch of science which is about the universe and its contents including also our world and tries to define the structures of these objects, their places in the universe, the laws of motion, their stages of formation and modifications they have been exposed to until the present day and events that may ocur in the future and it examines the movements of celestial bodies in general. As for astrophysics, which came into existence in 19th century, it deals with the physical properties of celestial bodies.
 

History of Astronomy


Events such as change of day and night, seasons that follow each other, view of the sky at starry nights, rising and setting of the moon, sun and other celestial bodies and some of them being seen all the year round are the reasons drawing the attention of people to the sky throughout the year. Celestial bodies whose movements are diffrent from the general movements of stars are classified as planets and Mercury, Venus, Mars, Jupiter and Saturn were the first planets discovered in this regard. In the meantime, it was ascertained that the Sun and the Moon do not follow the general movements of planets.

The first known astronomical observations were made during the time of the Babylonians and the division of day and night to 12 hours was conducted during this period. The astronomical knowledge of the Egyptians was more advanced. The construction of pyramids with a conscious and precise astronomical orientation and their being made in a manner to be amazed even today give a general idea about the ancient Egyptian’s knowledge of astronomy.

In ancient Greece, such mathematicians as Thales and Pythagoras were interested in astronomy. Eratosthenes, who lived in Alexandria in BC 3rd Century, calculated quite precisely around the world. Having lived in BC 2th century, Hipparchus was one of the first recognized astronomers of the era. Although the heliocentric astronomical theory was previously posed, (the theory of Aristarchus) Hipparchus also determined the length of the years and months with a remarkable precision and prepare a highly sensitive star map and catalogue. He gave the location and description of about 850 stars and classified the stars according to their brightness. This classification is used even today. He also identified the irregularities occur in the movement of the Moon due to the Sun’s gravity. Later on, basing on the determination of Ptolemi Hipparchus who lived in A.D. 2nd century, he set up a universe system and this Theory of Ptolemy (Batlemyus) has maintained its validity for 1400 years.

 

 

Modern Astronomy


Simple explanation of the movements of celestial bodies was made by Copernicus (1473-1543)  through assuming the sun as the center. The missing point in Ptolemy and Coprnicu’s systems was the lack of a physical basis. As well as explaining the kinematic aspects of the system, Galileo (1564-1642) ve Newton (1642-1727) have established a foundation of modern astronomy by also describing the dynamic sides of it. One of the scientists contributing to modern astronomy is Jonannes Kepler (1571-1630). The three “Law of Planetary Motion” found by him as follows:” 1-Planets move on an elliptical orbit with the sun at one focus. 2- As planets move around the sun, they scan equal fields combining the sun with planet in right and equal times. 3- The squares of the rotation periods of planets are proportional to the cubes of the average distances of the sun. Keppler has investigated these laws through trial and error method for 20 years but they were deprived of a mechanical basis until Newton put forward the laws of gravity in 1687. Though Jupiter was observed in 1610 on its satellite revolving around itself by Galileo via the telescope he made, Copernicus’s opinion of the universe gained validity in 1627.

 

Branches of Modern Astronomy


Astrophysics: It examines the composition of celestial bodies, energy sources and the distribution of energy in their spectrums.

Celestial Mechanics: A branch of science dealing with the events arising from the movements of celestial bodies.
 

Cosmology:  It investigates the overall distribution of galaxies in the universe and the reasons of this ditribution.

Astrometry: To correctly put forward the positions of heavenly bodies through the help of the movements of the stars and planets, distance of the stars or with any information that can be obtained from these studies.

Photometry: It is also called as full spectroscopy. It measures the intensity of radiation coming from the space.

Spectroscopy: It is used to look at in more detail to the radiative output of celestial objects.

 

 

The Main Tools Used By Astronomers

 

Optical Telescope: This tool which is known in astronomy from time immemorial is used in observing celestial bodies from the earthly platforms. Lately, giant optical telescopes through which not only the planets of the solar system but also even the galaxies in very distant places can also be observed have been produced.

Radio Telescope: Considered as the most important invention of modern astronomy, this tool is used in the study of the radiation emitted by celestial bodies. It is thanks to this device called as the ear of space that the discovery of pulsars and quasars has been possiblewhose existence can only be understood through the radio waves they spread.


Spectrograph: It is an instrument used to determine the spectra of celestial bodies. However, all the devices used by today’s modern astronomers are not limited with these devices. Numerous modern equipment from artificial satellites rotating around the world to microcomputers have entered the order of modern astronomy.

 

Main Study Areas of Astronomy


The Sun: The first phase of astronomical studies is the sun which is the closest star to us. Chinese astronomers had identified spots in the sun thousands of years before the invention of the telescope. Galileo made some findings with its small telescope in 16th century. The current astronomical researches examine on a large scale the interaction between the sun’s radiation and magnetic field and the world’s magnetic field and atmosphere. In fact, the sun is extremely important in terms of obtaining information from the stars. Because the sun is the closest star to us. It is possible to measure the temperature of the elements that make up the sun by examining the solar spectrum. In general, the sun is examined in four sections:

The Inside of the Sun: There is a vast territory under geosphere where energy is transmitted to the outside by convection. There is also a wide range of area under this region where energy  is transmitted to the outside through radiation. Energy coming from the core of the Sun occurs as a result of nuclear fusion which consists of via hydrogen atoms’ turning into helium atoms. Today, the transformation of energy through radiation and convection and nuclear reactions are issues with which technical and empirical astronomy engage in.

Solar Wind: As anyone can guess, the external  border of Corona flow mostly depends on how it is defined. Beyond the flow of Corona, there is a continuous radiation towards outward and the flow of electrically charged particles. Sometimes, large clouds generated by the small particles seperates from the Sun during the explosions in the chromosphere. Occasionally, the continuous flow of radiation and particles generates solar winds, which follow the withdrawal of the sun’s magnetic field, together with these clouds towards the depths of the solar system.

Photosphere: It is the visible face of the sun. Spots that ocur in this layer constitute one of the main subjects of solar investigations. Sunspots are areas where major activities take place. They are cooler than the photosphere which surrounds them. They are related to the sun’s general magnetic field. The intensity of magnetic field is high in the aforementioned areas. The stain period observed as the increase in the number of sunspots and their reaching to the maximum and their decreasing again continues about eleven years. There is a huge radiation flow which causes geomagnetic storms that often have an impact on the earth’s atmosphere during the maximum operating. Sun spots are carefully monitored as these radiation flows are harmful to so many things from manned space flights to radio waves.


Chromosphere and Corona: There is chromosphere above the solar atmosphere and photosphere. This area is very transparent and extends to the corona above. The first white corona is seen in the best way during the solar eclipse. The temperature of corona is too high. The substance in it is ionized. The energy source of the temperature of the corona is one of the most important problems of solar physics.

Solar System: The correct structure of the system was solved by Copernicus who developed Great Andalusian scholar Nureddin al-Batruci’s helio-centric theory of the planetary system. When his theory gradually became a part of the truth, astronomers turned more of their attention to the physical properties of celestial bodies in the solar system.


Moon, the Earth and Planets:

 There are many questions to be answered about the moon. For example, if the Moon and the Earth is a system of two planets since their inception or may the Moon be a piece which seperated from the Earth in geological times or is it a planet stricken by the Earth’s gravitational force?


Stars: 

 The second important area of astronomy is the examination of the Milky Way and hundreds of billions of stars that make up other galaxies. Ancient Europeans thought that stars were small lights hanging in the sky dome. Greek astronomers regarded stars as suns. Even though it was identified later that stars consisted of red-hot gas layers, human beings were unable to learn the source of star energy until recently. Apart from all these, one of the important issues with which astronomy concerns is quasars. The existence of quasars which is estimated as the largest celestial bodies in space in terms of size and distance, can only be detected through the radio waves they spread. Different assumptions were made about the size of quasars. It is even suggested that these giant celestial bodies are as big as a galaxy. Astronomical satellite IRAS was sent into space in the year of 1983 and still revolves around the world with an altitude of 906 kilometers. Completing one of its round in 103 minutes, the satellite scans a slice of the sky in its each rotation. The information obtained in the meantime is recorded on conputers on Earth. More than 200,000 obdervations of celestial objects have been made via IRAS so far and thus more information than expected was obtained.

Major important information: There are at least five new comets located close to the world, the presence of a small planet with a diameter of 2 km orbiting around the sun and more inside than Mercury which is known as the closest planet to the sun, the widespread presence of fine dust in the asteroid zone located between Jupiter and Mars in an area with a width of 100 million, the existence of dust clouds which rotate around itself and are numerous in the interstellar space, determination of about 50 stars which are thought to have planetary systems,

It is not possible with the observation tools in the world to directly determine whether stars closest to us have planetary systems or not. Because when Jupiter, the largest planet, was observed from the nearest stars, it reflects one and a half of a billion of the total light of the sun. Even it is impossible for the most advanced telescope to differentiate the light reflecting from Jupiter and the sun. As the satellite of astronomy moves around the outside of the Earth’s atmosphere, it is able to gather the necessary information. The Hubble Space Telescope which was sent into space via a space shuttle and seated in an orbit around the earth opened up great horizons in the science of astronomy. Through this telescope, which is a highly advanced device, galaxies and quasars billions of light-years away will be easily observed and in a sense the science of astronomy will be begun to be rewritten. In other words, astronomy is the geography of the next hundred years.

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