Oct 7
Near Yet Far: What is a Telescope and What Are the Different Types?
- Işık Arda Yardımsever
- Oct 7
- 5 min read
We all have things in life we want to see up close or with our own eyes. It might be a person, a pet, or a building. But I'd like to expand this list. Planets, stars, lurking enemies, or wild animals. Logically, most things we want to see are far away. However, there's an invention that can solve this problem: the telescope. Do you know how this device works in detail?
If your answer is no, you're in the right place, because we'll be examining what a full-range telescope is, how it works, and the different types of telescopes. Without further ado, let's get right to it.
Contents
What is a Telescope?
A telescope is an optical instrument that allows the user to see distant objects closer to the eye, thanks to a zoom lens at its tip . There are two basic types of telescopes: ground-based and space telescopes. There are also refracting, reflecting, and compound telescopes.
How Does a Telescope Work?
Optical telescopes, the most common , collect light from distant objects and focus them to produce a magnified image. Reflecting telescopes work by reflecting the image onto a primary mirror and then a secondary mirror. Radio telescopes, on the other hand, collect radio waves and convert the data into signals. Infrared telescopes detect the heat emitted from objects and convert them into images.
Ultraviolet, X-ray, and gamma-ray telescopes cannot work on Earth because these rays cannot pass through the atmosphere, so they are placed in space.
What is a Telescope Used For?
Besides making distant objects appear closer, what are telescopes used for? Telescopes are also valuable information-gathering tools in satellite tracking, space observation, weather monitoring, military observation, nature observation, and maritime science. For example, we discovered our solar system centuries ago with a telescope that showed the planets.
Telescope Usage Areas
Whether used for personal hobbies, military missions, or space observations, telescopes have various uses. To summarize:
Astronomy: To track stars, planets, and other celestial bodies.
Space Observations: To observe black holes, supernovas, and the universe itself and its laws.
Radio Astronomy: To explore the unseen universe with radio waves.
Military Purposes: For target tracking and reconnaissance.
Satellite and Spacecraft Tracking: To monitor the location and movements of artificial satellites.
Nature and Wildlife Observation: To observe animals and natural phenomena that are dangerous to approach.
Seafaring and Navigation: To see beyond the horizon.
Education: To provide education to students interested in space and observation.
Amateur Observation: For those who have made it a hobby to personally witness space.
As you can see, we use this optical device in almost every important field, not just as a telescope.
Differences Between Ground Telescope and Space Telescope
The biggest difference between ground and space telescopes is their location and the quality of their observations. As the name suggests, ground telescopes are located on Earth, while space telescopes are located outside the Earth's atmosphere.
Because ground-based telescopes are located deep within the atmosphere, weather conditions, light pollution, and atmospheric fluctuations affect the quality of their observations. Because space telescopes are not affected by these factors, their observation quality is consistently higher. For example, the high-quality photographs from the James Webb Space Telescope made headlines around the world.
On the other hand, ground-based telescopes are less expensive to maintain and develop, while space telescopes are the opposite. However, due to their high-resolution ultraviolet or infrared observation capabilities, they are normally expensive.
Who Invented the First Telescope?
The history of the telescope begins with Hans Lippershey of Holland on October 2, 1608. Lippershey introduced the telescope with the message that it would "see distant things as if they were near." Ironically, a few weeks after this invention, Dutch lens expert Jacob Metius applied for a patent for the same device. However, Metius's application was rejected. Furthermore, Galileo Galilei, who lived during the same period, learned of the resulting optical device and developed his own version, deciphering the logic of the solar system.
The first space telescope was built more recently. Yale University astrophysicist Lyman Spitzer came up with the idea in 1946, publishing a paper outlining the advantages of a large telescope to prevent atmospheric distortion. Nearly 20 years later, on December 7, 1968, NASA launched the first space telescope, the Orbiting Astronomical Observatory 2 (OAO-2), nicknamed Stargazer.
Types of Telescopes from Past to Present
The telescope has evolved from a small lens at its tip to a massive device capable of making various observations in space. Now, let's briefly examine all the different types of telescopes and their features.
The First Telescopes
These are the first models to appear in the 17th century. They focus light through a lens, producing an image. Galileo Galilei was the first person to use these telescopes for space observations. They enabled detailed observations of bright celestial bodies such as the Moon and Jupiter's moons. Due to optical problems such as chromatic aberration caused by the lenses in these telescopes, more advanced models were quickly required.
Reflecting Telescopes
Developed by Isaac Newton in 1668 , it is considered a milestone for telescopes. Compared to eyepiece telescopes, it collects and focuses light using concave mirrors instead of lenses . Because the mirrors don't distort color, images are clearer and more accurate. Thanks to their easy production in large sizes, most observatories today use advanced versions of these telescopes.
Catadioptric Telescopes
Catadioptric telescopes, also known as hybrid telescopes, have both reflecting and refracting elements. Developed in the early 20th century, these optical instruments are both portable and offer high image quality. Because they have minimal optical aberration, they are often preferred by amateur observers.
Radio Telescopes
First developed in 1937 , radio telescopes operate using radio waves rather than light and are known for their large satellite dishes . Compared to other ground-based telescopes, users can observe without being affected by clouds, dust, or other weather conditions. While they don't provide any visuals, they can gather sounds from the universe, providing information about galaxies, pulsars, and black holes .
X-Ray Telescopes
They are specialized space telescopes designed to observe the hottest and most energetic events in the universe . Their first use was the Uhuru Satellite , meaning "freedom," launched by NASA in 1970. X-ray telescopes can observe high-energy regions such as black holes, neutron stars, and supernova remnants.
Space Telescopes
These telescopes are placed in orbit to avoid optical distortions caused by the Earth's atmosphere . The most well-known example is the Hubble telescope, launched into space by the United States in 1990. These telescopes can observe in ultraviolet and infrared wavelengths, in addition to visible light. Furthermore, because they are located in space, the images are clearer and of higher quality.
Observatories in Türkiye
There are currently 12 observatories in Türkiye. These are:
Observatory | Founding Year |
Kandilli Observatory | 1868/1911 |
Istanbul University Observatory | 1935 |
Ankara University Observatory | 1963 |
Ege University Observatory | 1965 |
Cukurova University UZAYMER | 1991 |
TUBITAK National Observatory | 1997 |
ÇOMÜ Ulupınar Observatory | 2002 |
Erciyes University UZAYBİMER | 2009 |
Ataturk University ATASAM | 2012 |
Inonu University Observatory | 2012 |
Adıyaman University Observatory | 2015 |
Eskişehir Technical University Yunus Emre Observatory | 2017 |
Additionally, the Eastern Anatolian Observatory at Atatürk University is currently under construction.
Where is the World's Largest Telescope?
The Large Binocular Telescope (LTM) and the James Webb space telescope are currently the largest. The LTM has a lens diameter of 8.4 meters, and the Webb has a lens diameter of 6.5 meters.
However, they will lose their top spot to both telescopes in the coming years. NASA is building a more comprehensive space telescope than James Webb with SPHEREx. For the ground, the European Southern Observatory (ESO) will attempt to break the record in 2029 with the Extremely Large Telescope, which has a 39-meter diameter lens.
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