Week 3 Telescopes in Astronomy Paper

Topics: Hubble Space Telescope, Astronomy, Electromagnetic radiation Pages: 6 (1472 words) Published: April 23, 2015
Helen Threet
April 20, 2015
Telescopes in Astronomy
Telescopes have proven to be one of the greatest inventions in the science of astronomy. This instrument, which makes far-away objects more visible has facilitated both learning about and understanding our universe. This paper will discuss the importance of telescopes, their three major designs, and the strengths and weaknesses of different locations for telescopes. In addition, this paper will discuss the frequencies of light and the role they play in telescopes. Without the telescope, many discoveries in the field of astronomy would not have been possible. Invention of the Telescope:

While there has been debate as to who invented the first telescope, the first person to apply for a patent for one was Hans Lippershey, in 1608 (Cox, 2013). Galileo designed his own version of the telescope in 1609, and was the first person to use one to look at outer space (Cox, 2013). Before this point, dominant belief was that the universe was geocentric; the Sun evolved around the Earth. The use of telescopes helped to prove the Copernican system, in which the planets revolve around the Sun. This discovery changed the way people saw the universe and their places in it. Telescope Designs:

The three major deigns of telescopes are reflecting, refracting, and catadioptric. All three types have the "same light-gathering properties, despite differences in size and weight" (Sharma, 2015). They all collect light in order to focus, magnify and examine it through an eyepiece, however they all use different techniques to accomplish this. Each design has unique advantages, as well as disadvantages. Reflecting telescope:

In the place of a lens, a concave mirror gathers light and focuses it onto yet another mirror. The image is reflected to a flat, secondary mirror, which then reflects the image through an opening at the side of the tube of the telescope (Sharma, 2015). Advantages to the reflecting telescope are that they are relatively simple to use, and are excellent when looking for nebulae, star clusters, and remote galaxies. They are also portable and compact, and deliver very bright images. Disadvantages include that they are not suitable for terrestrial applications, and because the tube of the telescope is open to the elements, they require more maintenance and care than other types of telescopes. Refracting telescope:

Refracting telescopes are among the most common telescopes in use. In a refracting telescope, a thin, long tube passes the collected light in a straight line from the objective lens to the eyepiece (Sharma, 2015). Advantages include a simple design, and relative ease of use. They are best used for binary stargazing, planetary, lunar, and distant terrestrial viewing. Unlike the reflecting telescope, the tube of a refracting telescope is sealed in order to help protect the optics from dust and dirt. Disadvantages to the refracting telescope are that they are heavier and bulkier than reflecting telescopes, and are less suitable for the viewing of nebulae and distant galaxies. Catadioptric telescope:

Catadioptric telescopes use a combination of both lenses and mirrors, folding optics to form images (Sharma, 2015). There are two designs of catadioptric telescopes: the Maksutov-Cassegrain design and the Schmidt-Cassegrain design (Sharma, 2015). The Makustov-Cassegrain's design has a thick, curved correcting lens, as well as a secondary mirror. The Schmidt-Cassegrain, on the other hand, has a thin correcting lens, which the light enters and hits the primary mirror, which reflects the image up, until it is reflected by a secondary mirror (Sharma, 2015). While the Maksutov-Cassegrain telescope has slightly better resolution for observing planets; "[I]t takes a long time to reach thermal stability" (Sharma, 2015). Overall, both types of catadioptric telescope are highly versatile, and have the best near-focus capabilities. Advantages include that they are...

Cited: Cox, L. (2013). Who Invented the Telescope? Retrieved from http://www.space.com/21950-who-invented-the-telescope.html
Garner, R. (2014). Hubble Space Telescope. Retrieved from http://www.nasa.gov/mission_pages/hubble/story/index.html#.VMVGOf6ySYI
Hubble site. (n.d.). How does light carry information about stars, galaxies and other celestial objects? Retrieved from http://hubblesite.org/reference_desk/faq/all.php.cat=light
Melina, R. (2010). Why Are Space Telescopes Better Than Earth-Based Telescopes? Retrieved from http://www.space.com/8286-space-telescopes-earth-based-telescopes.html
Phys Org. (2009). Astronomers find coldest, driest, calmest place on Earth. Retrieved from http://phys.org/news170932769.html
Sharma, G. (2015). Understanding Telescopes. Retrieved from http://www.telescopes.com/telescopes/helpunderstandingtelescopesarticle.cfm
Telescopes. (2015). Understanding telescopes. Retrieved from http://www.telescopes.com/telescopes/helpunderstandingtelescopesarticle.cfm
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