Sample Astronomy Essay on The History of Radio Telescope

The History of Radio Telescope

The radio astronomy world has been flooded with establishment of vast interferometer projects, yet the single-dish telescopes have continued to contribute immensely in this field. Development of radio telescopes began by understanding the transparency of the atmosphere towards electromagnetic waves holding different frequencies. However, the development of larger single-dish radio telescopes does not happen without limitations, even though it is not the only way of increasing resolution. Radio interferometers have been utilized to enhance angular resolution and reduce the construction of huge telescopes to facilitate vision of far objects. Although more discoveries are being made in radio telescopes, the establishment of single-dish telescopes led to surfacing of interferometry, a technique to eradicate poor resolution in radio images and generate high resolution from single-dish telescopes.

Development of Single Dish Radio Telescopes

A radio telescope incorporates a directional antenna designed to obtain radio waves from space. According to Cheng, radio telescopes are astronomical instruments used to detect and collect radio waves from the universe (339). Directional antennas are also utilized in tracking and accumulating data from space explorers. Radio telescopes are usually large dish antennas used distinctly or in a group of dishes. The development of radio telescopes began almost a century ago when astronomers endeavored to investigate sources of interference in radiotelephone service. Karl Jansky was the first person to develop a directional antenna, which was transformed into the first radio telescope in 1928, and in 1932, he discovered radio signals that were generated from the Milky Way galaxy (Cheng 340). Later on, Grote Reber, a radio operator, came up with the paraboloidal reflector radio telescope, which is still commonly used today. His instrument was capable of surveying the sky at ~160 Megahertz. Reber’s multi-frequency observations exposed the non-thermal nature that radio emission possesses, thus, making a radio antenna produce a poor angular resolution. .

Generally, a single dish radio telescope incorporated a parabolic reflector that directed incoming radio frequency energy towards a receiver. Single dishes were able to chart the smooth extended emission from the Milky Way, even without an angular resolution that could locate the positions, in addition to determining the structure of detached radio sources. Radio interferometry emerged to offer higher angular resolution for the study of discrete radio sources. The development of radar during the WWII to enhance communication helped in the improvement of antennas. After the WWII, scientists began to investigate radio signals that came from space. In 1946, an interferometer that combined two separate telescopes was discovered by Ryle and Vonberg to improvise the one that brought reflected beam coming from the sea and direct beam coming from the sky. An interferometer is an apparatus that allow wave interference to have precise measurements in terms of wavelength. Astronomical radio interferometers support a number of parabolic dishes that are either one-dimensional or multi-dimensional.

The radio astronomy became a fundamental undertaking for investigating both galactic and extragalactic phenomena in the 1970s. The telescope antenna expanded in size, as well as precision since the WWII radar dishes, and the larger size guaranteed greater resolution and sensitivity (Sanders 38). This type of development came with low electronic noise, as dishes could detect fainter signals within a short duration. This led to emergence of large steerable single-dish telescopes, which came in different measurements. For instance, the Australian Telescope with six-22m dishes was constructed in the 1980s (Cheng 341). It had large radio interferometer components that made angular resolution to be better than the components found in the visible wavebands with different wavelengths.

During the inception of radio telescopes, the angular resolution was approximately 300 and such resolution depended on the size of the apparatus in wavelength. For many years, astronomers perceived that the resolution from radio telescopes would never be better than resolution from optical telescopes due to their wavelength (Kellermann and Moran. 457). However, this was never true, as high-resolution techniques have emerged faster at radio than they have at optical wavelengths. The Five-hundred meter Aparture Spherical (FAST) radio telescope is expected to become the world largest operating single-dish telescope very soon, with the capacity to explore on HI galaxy study, pulsar-black hole structure, and radio signals that emanate from exoplanets (Zhang, J 219).

Advantages of Radio Interferometers

Radio interferometer emphasized on attaining high resolution using a single telescope having a diameter that is equal to the distance that separate two antennas at a given length. Immediately after WWII, radio astronomers began to utilize interferometry techniques to enhance the angular resolution to beat the more conventional way of using filled-aperture instruments (Kellermann and Moran. 459). Interferometry has endeavored to create a gigantic telescope from numerous small telescopes to enhance reception. Radio interferometers are essential because they assist in increasing the resolution in radio band. Radio interferometers are capable of solving the problems of positioning timing service through establishment of long base interferometers (Fedotov, et al 45). In radio interferometer, an astronomer does not require to increase the antenna’s diameter to enhance the vision of distant objects.

The motivation behind interferometry was to identify radio sources that harbored plausible counterparts. Radio interferometers are more beneficial than auto-tracking antennas because they do not require large-diameter antennas (Kawase 5). They utilize small antennas, which are placed at fixed positions. Rather than building gigantic telescope to view the space, radio interferometers utilize sophisticated techniques to merge single elements into multiple components that work together to develop a single powerful telescope. They do not require drive mechanisms in case the tracking target happens to be a geostationary satellite.

Modern radio interferometers have separated radio telescopes that can observe same object when connected through coaxial cable or optical fiber. This has helped in increasing the total signal collected, as well as increasing resolution through Aperture synthesis. Establishment of a combined telescope, which incorporates different antennas that are further apart helps in developing high quality images. Unlike optical telescopes, radio telescopes are not affected by clouds or extremely poor weather conditions, hence, can be utilized even when the sky is cloudy.

Major Discoveries after Detection of Radio Waves

After the discovery of radio waves in the 1930s, radio astronomers continued with their explorations, which led to exceptional understanding of the universe. The rapid technological development that occurred during WWII illustrated a huge progress in radio reception methods even though it was carried out secretly. It was apparent that radio telescopes and optical astronomy brought different perceptions of the sky. When the WWII ended in 1945, some groups of astronomers began an exploration of radio emission coming from the sun by utilizing the available radar equipment and later on using interferometers (Swarup 75).

The theory on cosmology created a major ripple in the astronomy studies. In 1955, John Wheller devised the imaginable existence of a body that had no mass using electromagnetic radiation only (Ciufolini, et al 2). Wheeler discovered that an object could be produced out of gravitational radiation, or from electromagnetic radiation, and be held together by the gravitational attraction that it generates. In the 1960s, the study of detection of gravitational waves got underway, which expanded the research on general relativity and gravitation. The study of ultraviolet, infrared, X-ray, and gamma-ray brought radical transformation that enhanced the knowledge of the universe.

The discovery of radio telescopes led to the research on quasi-stella radio source, or super massive objects that are formed through intense gamma burst (Akintola 89). A quasar, which is an optically bright galaxy that was discovered in spectral lines of 3C273, has a magnitude of 13. It incorporates a compact radio source with a radio jet, as well as optical and X-ray jets (Swarup 78). Quasars are extremely glowing and initial exploration categorized them as sources of electromagnetic energy. Quasars survive only in galaxies that have super-massive black holes whose masses are billions of times that of the sun (Redd n.p). The existence of Black Holes in the galaxies was initially established through radio astronomy observations, but confirmed through optical and X-ray observations.

The Bing Bang Theory could not have become a success without the research on radio telescopes. The Cosmic Microwave Background Radiation (CMBR) became the most elementary observations in the universe in the 1960s due to its detailed explanation on the big bang fireball, which had an inflation epoch (Zhang, T 157). The CMBR was found to exist at a temperature of ~3 K. The inflationary model expressed particular dilemmas, which include homogeneity of the Universe, as well as horizon problem. In the Bing Bang Theory, it was discovered that matter that contained protons, electrons, and neutrons appeared in the Universe when the temperature fall from ~1011 to ~109 K.

The detection of the pulsars by Antony Hewish and Jocelyn Bell in 1967 pushed the astronomers to research further on the definition of pulsars. Pulsars are highly magnetized, revolving neutron stars that emit beams of electromagnetic radiation. Hewish and Jocelyn discovered that pulsars had a highly accurate periodicity, and had a close relationship with neutron stars. Their precise periods matched a highly accurate clock that exceeded atomic clock, thus, offering essential tests for the General Theory of Relativity. The two types of pulsars, Crab and Vela, have played a key role in pulsar astronomy, particularly in the electromagnetic and gravitational fields (McNamara 67). Pulsars gave rise to supernova remnants as well as neutron Star, and due to collapsing of the parent stars; the neutron stars begin their revolution at a split of second.


The development of radio astronomy has experienced numerous discoveries that have changed the insight of Universe. The propositions of these discoveries are still in their gestation period, as more researches are being carried out to gain more insights. The process towards development of single-dish radio telescope began after the invention of radio waves in the 1930s. The big rotational antenna failed to maintain a consistent pattern of resolution, leading to utilization of multiple antennas to hold radio data. To enhance reception and resolution, astronomers came up with radio interferometers to combine different radio telescopes in a parabolic arrangement. Since the discovery of radio waves and Milky Way as its source, several discoveries have been made, thus, creating a different perception of the Universe. According to Australia Telescope National Facility, the future for radio interferometry is still open for space-based mission

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