Telescope (Meaning and Explanation)

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 It is an optical instrument developed for the purpose of observing distant objects through the management of light and its properties. It is a fundamental tool for the study of Astronomy, and one of those that most profoundly revolutionized human beings' conception of the universe.

Its operation obeys the principle of image magnification, that is, the alteration of visible light patterns to enlarge what is observed, in the same way that binoculars work, only much more powerfully. For this, uses convex type converging lenses through which the light coming from what we want to see refracts.

Of course, modern and improved versions of telescopes use new technologies that make the most of these principles, managing to obtain images from unknown regions of the universe.

Invention of the telescope

The invention of the (optical) telescope It is attributed to the German lens maker Hans Lippershey (1570-1619), first to design the artifact, and the famous Italian scientist Galileo Galilei (1564-1642), who just by reading the description of the first telescope created his own in 1609.

Galileo's genius allowed him to create an improved version, which does not deform the images and allows them to be magnified six times, twice the original version. This changed his life, as he proceeded to further perfect his invention, managing to magnify what he observed eight to nine times.

However, there is also ample evidence that Galileo did not yet fully master the laws of optics. In fact, although he built more than 60 telescopes for the Republic of Venice, only a handful were truly efficient.

Telescope Evolution

griffith observatory telescope history — In the 19th and 20th centuries, large telescopes were built and are still in use.

Based on his studies in 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 were required, so new versions were invented: Giovanni Cassini (1625-1712) discovered the fifth moon of Saturn in 1672 with an 11-meter telescope, and Johannes Hevelius (1611 -1687) built one of 45 meters. Some were suspended in the air and were called “aerial telescopes.”

However, the French priest and philosopher Marin Mersenne (1588-1648) had proposed the use of parabolic mirrors in 1636. in telescopes. The Scottish astronomer James Gregory (1638-1675) used this resource many years later, giving rise to the so-called “Gregorian telescopes”, which could not be manufactured correctly.

Later, the famous English physicist Isaac Newton (1642-1727) published his studies on optics in 1666, demonstrating them through the construction of a new model of telescope. So, The first “Newtonian telescope” was completed in 1668 managing to correct the until then 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).

From then on a new generation of astronomers and inventors appeared: James Bradley, Samuel Molyneux, Mikhail Lemonósov, William Herschel (creator of the 40-foot “Herschelian telescopes”) and William Parsons, who in 1845 built the 16-foot “Parsonstown Leviathan.” meters focal length, the largest in the world until the construction of the Hooker Telescope 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.

Telescope Features

Telescopes can range in size from personal amateur 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 clarity of detail.
Focal distance Just as we must place text at a certain distance from our eyes to correctly focus the view, telescopes also require an internal length, which separates the main lens from the focus or objective where the eyepiece is located.
Limit 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 that a telescope magnifies the object observed, according to the relationship between the focal length of the telescope and the eyepiece.

Types of telescope

telescope types refractor reflector — Telescopes can refract or reflect light.

There are various types of telescopes, such as:

Refractor telescope It operates as a focused 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 their name is due to the fact that, instead of using lenses to guide 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:

Aim The final lens of the telescope, through which the light enters first, just as in cameras.
Ocular The magnifying lens that brings the image directly to the eye.
Barlow lens Lens that allows you to magnify the observed image, doubling or tripling it depending on the optical system in which it is located.
Filter Small accessories that allow you to improve 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 Telescope stabilizing elements (especially the smaller ones).

The Hubble telescope

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 It is located in a circular orbit around the Earth, at 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 the usual distortion and light pollution of terrestrial 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, They operate based on the same principle: that of light distortion through 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 modern sciences.