PHYS1600 Assignment on Telescope

ESSAY: HISTORY OF TELESCOPE

PHYS1160

1. Introduction Nowadays, throughout the advancement of the technologies, human beings are being so curious about so many things and one of it is the objects in the sky. The astronomer is the group of people that has a great interest of the objects located in the sky. In order to know more about them, a set of tools are used including a range of telescope, observatories, space shuttles, space probes, and many more. So let us learn more about telescope. What is a telescope? Telescope is defined as a device, where lenses or mirrors are arranged in certain pattern to monitor any objects that is located outside the Earth atmosphere. Telescope works by capturing any collect electromagnetic radiation such as visible lights from a distance objects and allow for observation. Telescope is used to get an eyeful of the celestials object in the outer space such as the planets, the stars, galaxies, moons, and solar systems by making them visible, blazing and bigger to the eye of the astronomer. (Euro-Mission.Org 2007) With the help of the telescope, the astronomy were able to search and deepen their knowledge about the universe and simultaneously engineer a better model in explaining the events that happened in the past as well as predicting the events that may happen in the future.

2. Refractor Now let us take a step back and see how the telescope was first founded by the astronomies in the past. Basically the advancement of telescope can be classified into two types, the refractor telescope and the reflector telescope. What is the difference between the two telescopes? Refractor is telescope that uses the two lenses where the first lens job is to collect all the lights emitted by the distance object; meanwhile the second lens will magnify the object to our eyes. (Cain 2008) As for reflector telescope, it uses two mirrors, rather than two lenses. (Cain 2008) The creation of telescope began in the early seventeenth century; to be exact in the year 1608 by a German-Dutch lens maker namely Hans Lippershey. (King CH 2003) The earliest design of the refraction telescope by Hans Lippershey was a tube with a fixed lens which is the eye piece that is curved outwards and one adjustable lens that is curved inwards to adjust for its focus. (The Robinson Library 2009) General principles behind the design of the telescope are collection of light and focusing it to at a point to form an image. The amount of light that telescope able to collect is way greater compared to the amount of light Page 1 of 6 z3285292

Muhamad Nur Farhan Muhamad Fadzil

ESSAY: HISTORY OF TELESCOPE

PHYS1160

that human eye can gather, thus making distanced objects look bigger and sparkling. (Beardsmore N/A) The following year, an Italian famous astronomer Galileo Galilei had improved the telescope that was designed by Hans Lippershey. Galileo had successfully improved the refraction telescope where the telescope was able to magnify objects about thirty times larger than its original size. However, the flaw in the shape of the lens allowed the lens to get an eyeful of only vague, blurry and deteriorate image. The idea to solve the problem was found by another famous astronomer, Johannes Kepler. In the year 1611, the idea for further refinement on the refraction telescope was told by Johannes Kepler, the one who found the laws of planetary motion. In order to get a clearer image and larger field of view, he suggested an alteration of Galileo’s telescope arrangement by substituting both concave and convex lenses with convex lens. (Ilovindia.com N/A) The problem of blurry images of Galileo’s telescope can be corrected by using a complicated shape instead of sphere however; looking at the technology available that time is unable to construct the required shape, so the spherical aberration problem is not solved. (Iloveindia.com N/A) In the mid eighteen centuries, the solution for spherical and chromatic aberration’s problem in refraction telescopes was found. In 1729 Chester Moor Hall, an English jurist and mathematician had combined several types of lenses made of different material and solve for chromatic aberration problem. The idea is that when the light penetrates, one lens will separates the colour of light on the other hands the subsequent lens will combine it. (Encyclopaedia Britannia 2011) That is how the chromatic aberration’s problem was solved. As for the spherical aberration problem, John Dolland had altered Hall’s achromatic lens and successfully creating achromatic doublets. Achromatic doublets are modified version of achromatic lens where the curve of the lenses is reshaped to allow for light bending so that it could meet at a certain point and produce a clearer image. Currently, many observatories are using refraction telescope including Great Paris Exhibition Telescope of 1900, Archenhold Observatories, Lowell Observatories, Griffith Observatories and many more.

3. Reflector

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Muhamad Nur Farhan Muhamad Fadzil

ESSAY: HISTORY OF TELESCOPE

PHYS1160

In the year 1668, in order to adjust the refraction telescope’s design, Sir Isaac Newton had replaced the fixed lens with a spherical-shaped mirror. This spherical-shaped mirror that curved inwards is functioning by capturing the light before reflecting it to a flat and smaller mirror. After that the light will be reflected by the smaller mirror into the retina. By doing this, Isaac Newton is convinced that a reflector uses mirror with 3 inches radius can enlarge an object around 40 times of its original size. On the other hand, the refraction telescope will need six feet long refraction telescope to produce the same magnification. Besides that, the reflector telescope does not have the chromatic aberration problem, which is a serious problem faced by refraction telescopes. This is due to the facts that in the reflecting telescope, there is no lens used in it. Nonetheless, nothings are prefect. Newton’s new telescope still cannot escape from the problem of spherical aberration due to sphere-shaped mirror. In addition of that, in the production of mirror, the alloy of copper and tin is used and it may become stained thus required regular maintenances. (Henry CK 2003) As years past by reflection telescopes starts to become more attractive in the eye of the scientist. However, the fact that refraction telescopes are gaining more popularity than the reflection telescope among the scientist is undeniable. Thus fierce competition in the development of both telescopes had started. Among the most significant advancement in the reflection telescope was made by James Gregory in 1663 where he invented a parabolic mirror. James Gregory with his new parabolic mirror was able to eliminate the blurry images that appear due to spherical aberration problem. The reflection telescope is much shorter and compact as compared to the refraction telescope because reflection telescopes have a shorter focal length. In order to collect more lights from the objects that are further and dimmer, the telescopes will need a longer diameter for the parabolic mirror, and that is why the telescope is getting bigger in size as day goes by. Despite of the chromatic and spherical aberration problem being solved, reflection telescope is facing another challenge; due to its big in size the telescope is immobile or hardly to move around. Besides, as reflection telescopes are advancing and getting more sophisticated, another problem arises which is called as the atmospheric distortion. Atmospheric distortion is a phenomenon involving the light from outer space’s objects, when the light tries to penetrate the Earth atmosphere; it got bent and makes the objects to twinkle. Let us have a look to some of early reflectors such as the Hadley’s Reflector, Herschel’s Reflectors, Lord Rosse’s Reflectors and Melbourne Reflector. Page 3 of 6 z3285292

Muhamad Nur Farhan Muhamad Fadzil

ESSAY: HISTORY OF TELESCOPE

PHYS1160

Moving on to the age of large telescopes, which started in the early nineteenth centuries when a Germany chemist named Justus von Liebig found a way that could coat a thin layer of silver on a glass surfaces. A mirror is produced after the coating is polished. In 1856 and 1857, Leon Foucault and Carl August von Steinheil, physicists from Germany and French had succeeded in applying this technique to create mirrors for reflection telescopes. Thanks to this new technique, the scientist was able to build giant mirrors for observation purpose. It is reported that the largest mirrors been produced during that time was about 200 inches in diameter. (Pettit 1956) The advantages of using the way proposed by them in creating new mirror are the material was cheap. Besides, the maintenance of the mirror was easy too. Moreover, the mirror was collecting fifty per cent more light compared to the telescopes that uses normal metal alloy mirrors. In order to minimise the effects of atmospheric distortion, the astronomers’ initiative is to build huge telescopes up on the hills and remote areas. The place is far from the city because they believed that the city light and pollution may have some shares in contributing to the distortion during observation. When James Clerk Maxwell first discovered radio waves in the year 1865, a radio telescope was invented. In the year 1932, an engineer named Karl Jansky is trying to figure out the static that interrupted his company’s radio voice transmission when he accidentally discovered a wave emitted somewhere in the outer space. (Ghigo F 2008) The fundamental design of the telescope is about the same to the reflecting telescope where the dishes and parabolic reflector is used to collect waves into the receiver before it is interpreted by computer. Some of the examples of radio telescopes are including Reber’s telescope in year 1937 and Very Large Array (VAL) in year 1980. As the scientist eager to be the first that solve for atmospheric distortion, another new breakthrough in the modern astronomy history take place in the 1900s; the invention of the space telescope. Basically, a space telescope is a telescope that is operating without the problem of atmospheric distortion since its location is outside the earth atmosphere that is while orbiting the Earth. Besides, a space telescope has the property of radio telescope built in it, so it can detect all types of wavelength including X-rays and Gamma rays. Up to date, there are several of them; Hubble telescope, Compton observatory, Chandra observatory, and Spitzer telescope. (Amazing Space. 2006)

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Muhamad Nur Farhan Muhamad Fadzil

ESSAY: HISTORY OF TELESCOPE

PHYS1160

4. Plan for the future We have seen the history of telescope; how it evolved and expand align with the technology and requirement of the scientist at that time. Now we take a peek of what is going to happen in the future of astronomy where the scientists have already planned several projects. One of the plans is the Giant Magellan Telescope (GMT). GMT is an extremely huge telescope tthat utilises the latest possible technology to assist astronomers in exploring the new dimension of this universe. The size of this telescope is estimated at 2.5 up to 4 times bigger than the current largest telescopes available. (Overby, Dennis, 2005) The scientist also believed in the capabilities of GMT where it is predicted that GMT is able to produce image that is 10 times clearer as compared to the Hubble space telescope. This project is expected to be completed by the year 2018. (Overby, Dennis 2005) The last but not least is the European Extremely Large Telescope. This project is being dominated by the European Southern Observatory and is assisted by fellow European astronomers. The European Extremely Large Telescope project has started in 2005 where it is said to be a combination of 1000 individual hexagonal mirrors and forming a main mirror with a radius of 21 meters. It is said to be 15 times more powerful in terms of accumulating light compared to other telescope in the world. The construction of the observatories will take place at Cerro Armazones, Chile and is expected to complete by 2018. (European Southern Observatory 2010)

5. Conclusion In a nutshell, we can see that the progress and development of telescope since it first introduced back in 400 years ago. As we could see too, that since the construction of telescopes, it has been an eye opener and extremely useful tools for the astronomer to understand this universe thus searching of the new knowledge about the past, present and future of the space.

6. References:

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Muhamad Nur Farhan Muhamad Fadzil

ESSAY: HISTORY OF TELESCOPE

PHYS1160

Amazing Space. 2006. Telescopes From the Ground Up. [online] Available at: http://amazing-space.stsci.edu/resources/explorations/groundup/ [Accessed 15 May 2011].

Beardsmore N/A A simple explanation of how telescopes work [online] Available at http://www.easytorecall.com/how_telescopes_work.htm [Accessed 15 May 2011] Cain 2008 The differences between Reflectors and Refractors [online] Available at: http://www.universetoday.com/14436/the-difference-between-reflectors-and-refractors/ [Accessed 15 May 2011] Encyclopædia Britannica, 2011 "Chester Moor Hall." [online] Available at Accessed 15 May 2011]

Euro mission.org. 2007 What is a telescope? [online] Available at: http://www.eusomission.org/What_is_a_telescope.html. [Accessed 15 May 2011]. European Southern Observatory. 2010. The World's Biggest Eye on the Sky. [online] Available at: http://www.eso.org/public/teles-instr/e-elt.html. [Accessed 15 May 2011]. Ghigo F 2008 Karl Jansky and the Discovery of Cosmic Radio Waves [online] Available at http://www.nrao.edu/whatisra/hist_jansky.shtml [Accessed 15 May 2011] Iloveindia.com N/A Johannes Kepler [online] Available at http://lifestyle.iloveindia.com/lounge/johannes-kepler-2776.html [Accessed 15 May 2011]

King, Henry, 2003. The History of Telescope. 2nd ed. N. Chemsford, MA: Courier Dover Publications. Overby, Dennis, 2005. Mirror,Mirror. The New York Times, 30 August. 15-16 Pettit E 1956 The Reflector. Astronomical Society of the Pacific Leaflets [online] Available at http://articles.adsabs.harvard.edu//full/1956ASPL....7..249P/0000255.000.html [Accessed 15 May 2011] The Robinson Library 2009 Hans Lippershey [online] Available at http://www.robinsonlibrary.com/science/astronomy/instruments/lippershey.htm [Accessed 15 May 2011] Youtube. (2009). Eyes on the Skies:400 Years of Telescopic Discovery. [Online Video]. 24 January. Available from http://www.youtube.com/watch?v=wXhU_FNCIZQ& feature=related. [Accessed: 15 May 2011].

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Muhamad Nur Farhan Muhamad Fadzil