How many stars do you see when you look up at a clear night sky? Likely more than you can even count on! What is more incredible was just how large and far away those stars are, and how we as human can learn about our universe by looking at starlight.
Humans have long stared toward the heavens, making an investigation to put meaning and order to the universe around them. Although the movements of patterns imprinted on the night sky (Constellations) were the easiest to track, other heavenly (Celestial) events such as eclipses and the motion of planets were also charted and predicted.
Definition/Explanation of astronomy
Webster Dictionary defines Astronomy as “the study of objects and matter outside the earth's atmosphere and of their physical and chemical properties. A science concerned with objects and matter outside the earth's atmosphere and of their motions and makeup”. Astronomy can also be defined as the study of the sun, moon, stars, planets, comets, galaxies, gas, dust and other non-Earthly bodies and phenomena. Therefore, Astronomy is the study of the universe, the celestial objects that make up the universe, and the processes that govern the lifecycle of those objects.
Considering the size of the universe (which could be infinite, since the size is not known by the scientists), astronomy is an enormous field. The celestial objects that astronomers study include stars, galaxies, nebulae, and supernova. Because of the enormous distances between Earth and other objects, when astronomers look farther away, they are also looking back in time. This is because of the amount of time it takes the light we see to travel from the source to us here on Earth.
Astronomy is all around us. Just look up! We are all aware of the motion of the Sun through the sky during the day and the changing phases of the Moon at night. The motions of astronomical objects determine the day-night cycle, the seasons of the year, the tides, the timing of eclipses, and the visibility of comets and meteor showers. Easily observed astronomical events have formed the basis for time keeping, navigation, and myths or sagas in cultures around the world.
Astronomy excites the imagination. The beauty of the night sky and its rhythms are at once stunning and compelling. The boldness of our collective efforts to comprehend the universe inspires us, while the dimensions of space and time humble us. Astronomy encompasses the full range of natural phenomena - from the physics of invisible elementary particles, to the nature of space and time, to biology - thus providing a powerful framework for illustrating the unity of natural phenomena and the evolution of scientific paradigms to explain them. These proves to us the relevance of Astronomy in our society.
The people that study Astronomy are called Astronomers, and they are contemporary classified into two fields:
- Observational astronomers: focus on direct study of stars, planets, galaxies, and so forth.
- Theoretical astronomers: model and analyze how systems may have evolved.
Astronomers mostly rely on snapshots of bodies in various stages of evolution to determine how they formed, evolved and died. Thus, theoretical and observational astronomers tend to blend together, as theoretical scientists use the information actually collected to create simulations, while the observations serve to confirm the models — or to indicate the need for tweaking them. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.
Astronomy is also a participatory science. Many non-scientists have astronomy as a life-long avocation. Astronomy offers the possibility of discovery. The chance to find a never-before-seen supernova, nova, comet, or asteroid is very exciting, especially to nonprofessionals. Astronomy inspires work in the arts. From poetry and music to science fiction books and films, the ideas and discoveries of modern astronomy serve as inspiration for artists, for youngsters, and for the public at large. In the process, the works inspired by astronomy can serve as goodwill ambassadors for the value and excitement of physical science to many in society who do not otherwise come into contact with the sciences. Statistics confirm the widespread interest in astronomy.
Of all the sciences cultivated by mankind, Astronomy is acknowledged to be, and undoubtedly is, the most sublime, the most interesting, and the most useful. For, by knowledge derived from this science, not only the bulk of the Earth is discovered … ; but our very faculties are enlarged with the grandeur of the ideas it conveys, our minds exalted above [their] low contracted prejudices. (JAMES FERGUSON, 1757)
Its great advances notwithstanding, astronomy is still subject to a major constraint: it is inherently an observational rather than an experimental science. Almost all measurements must be performed at great distances from the objects of interest, with no control over such quantities as their temperature, pressure, or chemical composition.
Unlike most other fields of science, Astronomers are unable to observe a system entirely from birth to death; the lifetime of worlds, stars, and galaxies span millions to billions of years.
HISTORY OF ASTRONOMY
Some of the early significant history of Astronomy was that, early cultures identified celestial objects with the gods and took their movements across the sky as prophecies of what was to come. Though, this was now called the astrology, far removed from the hard facts and expensive instru¬ments of today’s astronomy, but there are still hints of this history in modern astron¬omy. Take, for example, the names of the constellations: Andromeda, the chained maiden of Greek mythology, or Perseus, the demi-god who saved her.
Astronomy was the first natural science to reach a high level of sophistication and predictive ability, which it achieved already in the second half of the 1st millennium BCE. The early quantitative success of astronomy, compared with other natural sciences such as physics, chemistry, biology, and meteorology (which were also cultivated in antiquity but which did not reach the same level of accomplishment), stems from several causes. First, the subject matter of early astronomy had the advantage of stability and simplicity— the Sun, the Moon, the planets, and the stars, moving in complex patterns, to be sure, but with great underlying regularity. Second, the subject was easily mathematized, and already in Greek antiquity astronomy was frequently regarded as a branch of mathematics. And third, astronomy benefitted from its close connection with religion and philosophy, which provided a social value that other sciences simply could not match.
Early Astronomy Image credit: Astronomy Trek Link
The astronomical tradition is of impressive duration and continuity. A few Babylonian observations of Venus are preserved from the early 2nd millennium BCE, and the Babylonians brought their science to a high level by the 4th century BCE. For the next half millennium, the greatest headway was made by Greek astronomers, who put their own stamp on the subject but who built on what the Babylonians had accomplished. In the early middle ages, the leading language of astronomical learning was Arabic, as Greek had been before. Astronomers in Islamic lands mastered what the Greeks had accomplished and soon added to it. With the revival of learning in Europe, and the European Renaissance, the leading language of astronomy became Latin. The European astronomers drew first on Greek astronomy, as translated from Arabic, before acquiring direct access to the classics of Greek science. Thus, modern astronomy is part of a continuous tradition, now almost 4,000 years long that cuts across multiple cultures and languages.
Ancient Times
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 possibly 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, Greek, Persia, India, China, Egypt, 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. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon 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 Ptolemaic system, named after Claudius Ptolemy.
Ptolemy is a Greek astronomer, one of his culminating works is the Almagest of Claudius Ptolemaeus (2nd century CE). Ptolemy built on the work of his predecessors — notably Hipparchus — but his work was so successful that it made older works of planetary astronomy superfluous, and they ceased to be read and copied. An innovation that appears for the first time in the Almagest is the equant point. As in the planetary theories of Hipparchus’s day, a planet travels uniformly around its epicycle while the centre of the epicycle moves around Earth on an off-centre circle.
A particularly important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the later astronomical traditions that developed in many other civilizations. The Babylonians discovered that lunar eclipses recurred in a repeating cycle known as a Saros.
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, and he proposed a model of the Solar System where the Earth and planets rotated around the Sun. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and invented the earliest known astronomical devices such as the astrolabe. Hipparchus also created a comprehensive catalog of 1020 stars, and most of the constellations of the northern hemisphere derive from Greek astronomy.
Astrolabe: it is used to identify stars or planets, and to determine local latitude given local time (and vice versa).
Credit: By Jacopo Koushan (User:Jacopo188)Photograph by Masoud Safarniya (User:M.safarniya) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26080692
The early Analog Computer designed to calculate the location of the Sun, Moon, and planets for a given date, is called Antikythera mechanism. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.
Middle Ages
Astronomy flourished in the Islamic world and other parts of the world. This led to the emergence of the first astronomical observatories in the Muslim world by 8th to 9th century. Theories and methods that had passed from the Babylonians and Greeks through Persia to India now goes back to the East. A good example is provided by the zīj of Muḥammad ibn Mūsā al-Khwārizmī (9th century). Al-Khwārizmī’s work is a confusing mixture of Indian, Persian, and Greek tables and techniques, but it helped establish an important genre of the zīj. A zīj is a handbook of astronomical tables, including tables for working out positions of the Sun, Moon, and planets, accompanied by directions for using them.
The ancient prototype was Ptolemy’s Handy Tables. Ptolemy’s Almagest was translated on at least four occasions into Arabic. Much of the translation activity was center on the Baghdad caliphate of the ʿAbbāsids (750–1258). With the pure geometrical form of Greek planetary theory now available, Arabic astronomers worked to master it and then to improve upon it. The zīj of al-Battānī (early 10th century CE) showed mastery of Ptolemaic planetary theory and improved values for some of Ptolemy’s parameters, such as the magnitude and direction of the Sun’s eccentricity. Hundreds of Arabic zījes from the 9th to the 15th century have been preserved. Some were based on Indian methods, but the great majority were in the tradition of the Almagest and the Handy Tables. A zīj that was very influential in the development of European astronomy was the Toledan Tables, compiled in Spain by a group of Muslim and Jewish astronomers, put into final form by Ibn Al-Zarqallu around 1080, and translated into Latin soon after.
In 964, the Andromeda Galaxy, the largest galaxy in the Local Group, was described by the Persian Muslim astronomer Abd al-Rahman Al-Sufi in his Book of Fixed Stars. The SN 1006 supernova, the brightest apparent magnitude stellar event in recorded history, was observed by the Egyptian Arabic astronomer Ali ibn Ridwan and Chinese astronomers in 1006. Some of the prominent Islamic (mostly Persian and Arab) astronomers who made significant contributions to the science of astronomy include Al-Battani, Thebit, Abd Al-Rahman Al-Sufi, Biruni, Ibn Al-Haytham, Naṣīr Al-Dīn Al-Ṭūsī, Ibn Al-Shāṭir, Abū Ishāq Ibrāhīm al-Zarqālī, Al-Birjandi, and the astronomers of the Maragheh and Samarkand observatories. Astronomers during that time introduced many Arabic names now used for individual stars. It is also believed that the ruins at Great Zimbabwe and Timbuktu may have housed astronomical observatories. Europeans had previously believed that there had been no astronomical observation in sub-Saharan Africa during the pre-colonial Middle Ages, but modern discoveries shows otherwise.
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets.
Credit: By Andrew Shiva / Wikipedia, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=28608413
Medieval Europe housed a number of astronomers. Richard of Wallingford (1292–1336) made major contributions to astronomy, including the invention of the first astronomical clock, the Rectangulus which allowed for the measurement of angles between planets and other astronomical bodies, as well as an equatorium called the Albion which could be used for astronomical calculations such as lunar, solar and planetary longitudes and could predict eclipses.
Scientific Revolution
During the Renaissance period in 1543 A.D, modern astronomy began to take shape when Copernicus published his “De Revolutionibus Orbium Coelestium” which used empirical evidence to revive Aristrachus’ heliocentric view of the Universe.
During 1609 A.D, Galileo used the newly invented telescope by Copernicus to make some incredible astronomical observations, including viewing Jupiter’s rotating moon system, and noting there were obviously objects in the heavens which didn’t revolve around the Earth. Galileo’s attempts to defend the heliocentric model of the universe landed him in direct conflict with the powerful church. In 1632 he was tried for heresy, forced to renounce and condemned, and spend the rest of his life under house arrest.
Sir Isaac Newton invented the first reflecting telescope in 1668 A.D, which used a curved mirror instead of a lens to look further into space. Newton later publishes his hugely influential book called “Philosophiae Naturalis Principia Mathematica” in which he agrees that the Earth rotates around the Sun and explains the reasons behind Kepler’s three laws. Though, Kepler did not succeed in formulating a theory behind the laws he wrote down. Newton also establishes the law of universal gravitation, which ushered in a new Age of physics and Enlightenment.
A replica of Newton's second reflecting telescope which was presented to the Royal Society in 1672.
Credit: By User:Solipsist (Andrew Dunn) - www.andrewdunnphoto.com, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=513483
Improvements in the size and quality of the telescope led to further discoveries. The English astronomer John Flamsteed catalogued over 3000 stars. More extensive star catalogues were produced by Nicolas Louis de Lacaille. The astronomer William Herschel made a detailed catalog of nebulosity and clusters, and in 1781 discovered the planet Uranus, the first new planet found. Laplace proposes the concept of Black Holes in 1798 A.D. The distance to a star was announced in 1838 when the parallax of 61 Cygni was measured by Friedrich Bessel.
Significant advances in astronomy came about with the introduction of new technology, including the spectroscope and photography. Joseph von Fraunhofer discovered about 600 bands in the spectrum of the Sun in 1814–15, which, in 1859, Gustav Kirchhoff ascribed to the presence of different elements. Stars were proven to be similar to the Earth's own Sun, but with a wide range of temperatures, masses, and sizes.
Star trails photographed in earth orbit from the International Space Station.
Image credit: NASA/Don Pettit NASA JSC Flickr account. Public Domain
Significant advancement in astronomy was also recorded in the 20th century to 21st century, such as the First radio telescope was built in the USA by Grote Reber, a Russian Sputnik 1 satellite becomes the first man-made object to orbit the Earth marking the beginning of the space age. Neil Armstrong and Buzz Aldrin walk on the Moon as part of the Apollo 11 mission, and Voyager 1 spacecraft launched to explore the outer solar system. The existence of the Earth's galaxy, the Milky Way, as its own group of stars was also only proved in the 20th century, along with the existence of "external" galaxies. The observed recession of those galaxies led to the discovery of the expansion of the Universe.
CONCLUSION
Astronomy Knowledge to man is very important in several aspects. It’s through it that mankind were able to discovered several technologies that brought easiness on how we can be able to processed enormous complex tasks. Through the Astronomy, systems such as GPS, airport scanner, satellite technologies were invented.
Current research in astronomy confronts a host of unanswered questions: “How old are we?”, “What is the fate of the Universe?”, “How unique is the Universe?” and “Could a slightly different Universe ever have supported life?” Pursuing these questions is a fundamental part of being human, yet in today’s world it has become increasingly important to be able to justify the pursuit of the answers.
As we have seen, research on Astronomy started right from the ancient times, and the exploration is to continue since there are several needs to study the universe in advance in order to explore more on new and upcoming technologies.
REFERENCES
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- Important Dates In The Timeline Of Astronomy (http://www.astronomytrek.com/important-dates-in-the-timeline-of-astronomy/) on 28 March, 2013. Retrieved on 15 February, 2020.
- Marissa R., Pedro R., Georgia B. & Lars L. C. (January, 2014.) Astronomy in Everyday Life: Communicating Astronomy with the public Journal. pg.30 – 35. (https://www.capjournal.org/issues/14/14_30.pdf). Retrieved: June 25, 2020.
- National Research Council 2001. Astronomy and Astrophysics in the New Millennium. Washington, DC: The National Academies Press. https://doi.org/10.17226/9839. (https://www.nap.edu/download/9839#). Retrieved: August 20, 2020.