ALL ABOUT TELESCOPES
How Telescopes Work
Telescopes are certainly one of the most useful and innovative inventions ever created. Even though what they do seems rather spectacular to some observers, the way in which they work is quite basic and straight-forward. Light is the primary factor that enables telescopes to function. Without light, it would be impossible for telescope to make an image appear as though it is closer to the human eye. Lenses are also an indispensable component of a telescope. The shape of the lenses rather than the lenses themselves is what makes them important. At this point, it is worth mentioning that not all telescopes use lenses. There are certain types of telescopes which use mirrors. Similarly, as with the case of telescopes which use lenses, it is the shape of the mirrors that make the telescope work and not the mirrors themselves.
When trying to explain how telescopes work, it is important to note that there are two main types of telescopes. These are the refracting and reflecting telescopes. Both these telescopes work using the same principles and provide the same output. The main differences between the two stem from the fact that one uses mirrors whilst the other uses lenses.
A reflecting telescope is one that uses only mirrors to focus light. This type of telescope uses what is called a concave mirror. Concave mirrors are those which have the ability to bend light: such mirrors are able to do this by reflecting light rather than by bending light as it passes through their surface. One of the main disadvantages of using a reflective telescope is the fact they can be highly impractical. Telescopes of this type have to be of a spectacular size before they can actually work. In fact, these telescopes have been known to be at least 3 times the size of a fully grown adult.
On the other hand, refracting telescopes are those which use only lenses to gather light. By focusing the light on their surfaces, these, lenses are able to make distant objects appear as though they were much closer. The two lenses used in a refractive telescope are convex-shaped. Convex lenses are actually able to bend light as it passes through their surface. This of course is quite different to reflecting telescope which bends light through reflection. The convex lenses of refracting telescope are specifically what makes distant objects look smaller. Of course, refracting telescopes are usually a lot smaller than reflecting telescopes. However, in order to view objects like stars which are very far away, refracting telescopes have to be a lot bigger than hand held versions.
This larger size is necessary because it allows the user to obtain a higher degree of resolution when viewing an object. Resolution is the ability of a telescope to not only make an object appear closer, but to also show minute details. The largest refracting telescope is located in Williams Bay, Wisconsin. It should also be noted that there are some telescope variants which use both mirrors and lenses. These types of telescopes are often complicated contraptions which also work in an almost inexplicable fashion.
In any case, when trying to understand how such telescopes work, the important thing to focus on is the ability to identify what kind of light they pick up. Examples of such telescopes include the X-ray telescopes and radio telescopes. These types of telescopes can be regarded as more advanced and sophisticated versions of the reflecting and refracting telescopes. They are also significantly more expensive than other telescopes because they can be used to view many diverse things like gases and pulsars.
World’s Largest Telescopes
Telescopes have a way of bringing things closer to us that we normally wouldn’t be able to see or reach clearly. With the help of telescopes, we are able to clearly see celestial bodies that are not visible to the naked eye. We can also get closer to evasive creatures that we might never be able to normally see up close in their native habitats. Scopes significantly increase our sense of sight, and enable us to magnify images so that we can appreciate them better and study them much more clearly. Though most of us are familiar with and have used such things as binoculars, telescopes, and microscopes throughout our lives, many of us have not had the privilege of experiencing the spectacular images that can be seen through some of the largest scopes in the world. These scopes are used to view images that most of us only dream of seeing.
The Twin Keck telescopes, located on the summit of Mauna Kea on the island of Hawaii, are the largest infrared and optical telescopes in the world. Each of these telescopes stands an unbelievable 8 stories high and weighs close to 60,000 pounds. Despite their extremely large size, however, the precision of these telescopes is unprecedented. The Twin Keck telescopes are used, of course, for studying and tracking objects in the sky. Using telescopes to aid in astronomy research has always posed problems in the past, due to atmospheric disturbances and the fact that the earth and all other celestial bodies are always moving. The Twin Keck telescopes use state-of-the-art primary mirrors that measure 10 meters in diameter and are composed of 36 segments. The mirrors constantly undergo precise computer controlled corrections to keep them working at maximum efficiency. By virtue of their optimum location, which ensures that they are affected by the least amount of atmospheric disturbances possible, as well as their state-of-the-art engineering, the Twin Keck telescopes have been able to provide astronomers with valuable information about the universe around us.
The SALT telescope, or the Southern African Large Telescope, is the largest telescope in Africa, and also holds the title as the largest optical telescope in the entire southern hemisphere. Officially unveiled in November of 2005, SALT allows astronomers from several different countries to study stars very closely, as well as to further study atmospheric origins. The SALT telescope has a 1O meter in diameter primary segmented mirror, which, like the mirrors on the Twin Keck telescopes, will be kept running at optimum efficiency using state-of-the-art computer technology. Using the Internet, researchers from places that are far away from the SALT telescope will be able to request and receive data remotely.
The Hobby-Eberly Telescope, more commonly known as HET, is located in Mt. Fowlkes, Texas. This impressive telescope has a primary mirror that weighs about 250 pounds and has 91 hexagonal segments. HET was built for a fraction of the cost that most telescopes of this caliber are built for, yet it works with optimum precision. Unlike other large scopes, the primary mirror is not automatically rotated to stay on track with stars or planets, but is rotated according to schedules set by the Resident Astronomer. HET is located in the McDonald Observatory in the Davis Mountains of Texas. It began operations in 1999, and has proven to be a valuable tool for those in the field of astronomy.
Without telescopes our view of the world and the universe around it would be much more limited. Though few of us can work with large telescopes like the ones mentioned, we can buy ones for our own use, and begin to broaden our horizons from our own backyards.
The Hubble Telescope
Long before mankind was able to send astronauts into space, astronomers conceived the idea of placing a telescope above the obscuring atmosphere of earth. Such an observatory in space was first proposed in 1923 by the German scientist Hermann Oberth, whose work inspired much interest in actual space travel. In the late 1940s through the early 1960s, scientific instruments installed on various rockets, balloons, and satellites produced enough excitement in the scientific community to hint at the possibility of the many discoveries that remained.
In 1962, four years after NASA was established, a study group from the National Academy of Sciences recommended that a large space telescope be developed. This recommendation was to be a long-range goal of the then fledgling space program, and was repeated by similar groups in both 1965, and 1969. The idea was popular, and the work was begun.
In 1968, the first successful NASA satellite for observing the stars was launched, with another following in 1972. These satellites gave scientists a wealth of information and support for a larger, more powerful optical telescope. The approval of the Space Shuttle, which had a capacity for not only man delivery, but also the servicing of large payloads, made this concept more fees able than ever before.
In 1973, NASA selected a team of scientists to establish the basic design of the telescope, along with the various instruments that would be necessary to serve their purpose. In 1977, a group of 60 scientists was formed from 38 institutions to refine the recommendations. That same year, congress authorized the funding for this project, which created more excitement in the scientific community. Now NASA could begin.
Soon after, NASA began assigning responsibility to the Marshall Space Flight Center in Huntsville, Alabama for the design, development, and construction of the space telescope. Goddard Space Flight Center in Greenbelt, Maryland was then chosen to lead in the development of the ground control center and scientific instruments needed to accompany the telescope. As interest grew, other organizations such as the European Space Agency became involved.
Several major universities also began assisting with the telescope. Work continued through the rest of the 1970s, and into the 1980s, where scientists selected various proposals, helped coordinate research, and generated the observing agenda of the actual telescope. Results of their investigations were also properly archived and distributed.
In 1985, the Space Telescope Operations Center at Goddard was established as the ground control facility for the telescope, where the observing agenda from the Science Institute was translated into computer commands, which were then relayed to the telescope. The data then received at the center was then translated into a format usable by the Science Institute. The control center also monitored the health and safety of the space telescope.
The actual construction process of the telescope spanned almost a decade, and was completed, instruments and all, in 1985. The launch of this telescope was originally scheduled for 1986, but was delayed during the Space Shuttle designed following the Challenger accident. In October of 1989, the telescope was shipped from Lockheed in California to the Kennedy Space Center in Florida, where it was launched aboard the STS-31 mission of the Space Shuttle Discovery on April 24, 1990. Since that time, scientists have continued to develop the Hubble Space Telescope, working hard to make it more accurate, and repairing various flaws that were discovered along the way. Since its launch, the Hubble Telescope has been able to produce images far superior to those of any telescope on the ground. Scientists will continue their work on the space telescope, creating better instruments and improving the overall ability of the Hubble.