- What is a telescope?
- Invention of the telescope
- Evolution of the telescope
- Telescope Features
- Telescope types
- Telescope parts
- The Hubble Telescope
- Telescope and microscope
We explain what the telescope is, the history of its invention, evolution, its parts and characteristics. Also, the Hubble telescope.
What is a telescope?
A telescope is an optical instrument developed in order to observe distant objects, through the handling of the light and its properties. It is a fundamental tool for the study of the Astronomy, and one of those who most profoundly revolutionized the conception of universe what does he have human being.
Its operation obeys the principle of the magnification of the images, that is, to the alteration of the patterns of visible light to enlarge what is observed, in the same way that binoculars work, only much more powerfully. For this, it uses converging lenses of the convex type, through which it refracts the light coming from what we want to see.
Of course, modern and improved versions of the telescope employ newer technologies that take the best advantage of these principles, managing to obtain images from regions unknown to the universe.
Invention of the telescope
The invention of the (optical) telescope is attributed to the German lens maker Hans Lippershey (1570-1619), the first to design the artifact, and to the famous Italian scientist Galileo Galilei (1564-1642), who just by reading the description of the first telescope he created his own in 1609.
Galileo's genius allowed him to create an improved version, which does not distort the images and allows them to be magnified six times, twice the original version. This changed his life, as he proceeded to further refine his invention, managing to magnify what he observed eight to nine times.
However, there is also ample evidence that Galileo had not yet fully mastered the laws of optics. In fact, although he built more than 60 telescopes for the Republic of Venice, only a handful were really efficient.
Initially this invention was called "spy lens". Later the name "telescope" was proposed by the Greek mathematician Giovanni Demisiani in 1611, during a dinner in honor of Galileo.
Evolution of the telescope
From his studies of optics, the German astronomer Johannes Kepler (1571-1630) suggested the use of two convex lenses for the telescope. Using his publications, new versions of this device emerged in Europe. Thus, the Dutch astronomer Christiaan Huygens (1629-1695) created the first "Keplerian" telescopes around 1655.
Given the limitations of the time, objectives with large focal lengths, for which new versions were invented: Giovanni Cassini (1625-1712) discovered in 1672 the fifth moon of Saturn with an 11-meter telescope, and Johannes Hevelius (1611-1687) built a 45-meter telescope. Some were suspended in the air and they were called "aerial telescopes."
However, the French priest and philosopher Marin Mersenne (1588-1648) had proposed in 1636 the use of parabolic mirrors in telescopes. The Scottish astronomer James Gregory (1638-1675) used this resource many years later, starting the so-called "Gregorian telescopes", which were not manufactured correctly.
Later, the famous English physicist Isaac Newton (1642-1727) published his studies on optics in 1666, demonstrating them by building a new model of telescope. Thus, the first “Newtonian telescope” was completed in 1668, managing to correct the hitherto inevitable “chromatic aberration”.
This new version revolutionized telescope making, until 50 years later it was further improved by the English inventor John Hadley (1682-1744).
Henceforth a new generation of astronomers and inventors appeared: James Bradley, Samuel Molyneux, Mikhail Lemonosov, William Herschel (creator of the 40-foot “Herschelian telescopes”) and William Parsons, who in 1845 built the 16-foot “Parsonstown Leviathan”. meters of focal length, the largest in the world until the Hooker Telescope was built in 1917.
Large reflecting telescopes were built during the 19th and 20th centuries. In 1980 new technologies made it possible to build even larger telescopes with better image quality: active optics and adaptive optics.
At the same time, proposals for telescopes using other wavelengths other than visible light began to emerge: radio telescopes, infrared, ultraviolet, x-ray, gamma ray telescopes, etc.
Telescope Features
Telescopes can be of various sizes, from hobbyist personal instruments to huge installations at international observatories. In all cases, however, its most important parameters are:
- Objective lens. Depending on the diameter and thickness (in millimeters) of the objective lens, which is the final lens of the device, the most external, a telescope will allow you to see further and with greater detail clarity.
- Focal distance. Just as we must put a text at a certain distance from our eyes to focus the view correctly, telescopes also require a length internal, which separates the main lens from the focus or objective where the eyepiece is located.
- Limiting magnitude. It represents the limit of what is observable, under ideal conditions, with a given telescope. It is equivalent to the idea of "power", and is calculated using a specific formula.
- Increases. It refers to the number of times a telescope magnifies the observed object, according to the relationship between the focal length of the telescope and the eyepiece.
Telescope types
Telescopes can refract or reflect light.There are various types of telescopes, such as:
- Refractor telescope. It operates as a centered optical system, capturing images of distant objects through a set of converging lenses, which distort the light that passes through them, according to the principle of light refraction.
- Reflecting telescope. The design of these telescopes comes from Isaac Newton himself, and its name is due to the fact that, instead of using lenses to conduct light, they use mirrors. They generally use two of them: one primary and one secondary, thus achieving a good balance between opening, quality and cost of the device.
- Catadioptric telescope. This type is the result of the mixture of the previous two, that is, it uses both mirrors and optical lenses, according to the so-called Schmidt-Cassegrain System. Some even use three mirrors instead of two.
Telescope parts
Although the exact composition of a telescope can vary greatly, its common elements are usually:
- Target. The final lens of the telescope, where the light first enters, just like in cameras.
- Ocular. The magnifying lens that brings the image directly into the eye.
- Barlow lens. Lens that allows you to magnify the observed image, doubling or tripling it depending on the optical system you are in.
- Filter. Small accessories that improve the observation, slightly obscuring the observed image when positioned in front of the eyepiece.
- Mount. The physical support of the telescope, when it comes to large sizes.
- Tripod. Stabilizing elements of the telescope (especially the smaller ones).
The Hubble Telescope
From outside the atmosphere, the Hubble telescope takes more direct images.One of the most famous telescopes in the world today is the one that pays tribute to the American astronomer Edwin Hubble (1889-1953): the Hubble space telescope. This one is in a orbit circulate around the Earth, 593 kilometers above sea level.
It was put into orbit in 1990 by the joint mission of NASA and the European Space Agency, since being on the outskirts of the atmosphere it does not suffer from the usual distortion and light pollution of ground-based telescopes. To this telescope we owe some of the most impressive images obtained of the deep universe.
Telescope and microscope
Both the telescope, which allows us to see distant objects, and the microscope, which allows us to see infinitely small objects, operate on the same principle: that of the distortion of light by means of strategically positioned lenses and mirrors.
Thus, they manage to bring otherwise impossible images to our eyes. Both instruments also had a totally revolutionary impact on the modern sciences.