The telescope is a truly fascinating type of instrument. From the first lunettes to Hubble and the more recent James Webb, they have been present in our history. And both on Earth and in space. They were also in the hands of military men and sailors, who used them for navigation, location and observation of the territory they were in. But also, of course, in the hands of scientists, whoMore precisely, in fact, this tradition begins with the revolutionary thinker Galileo Galilei.

Galileo didn't invent the telescope, it's true. The credit goes to Dutchman Hans Lippershey, a lens manufacturer. Galileo, however, hearing about the invention, didn't take long to build his own version. And more, to point it at the sky. After all, we have a new instrument that magnifies the image of the object we are observing. How would we see the moon, the planets and the starsThe brilliant Italian took his curiosity seriously. He could make out craters and mountains on the Moon, Saturn's rings, Jupiter's 4 largest moons and sunspots. He even saw a diffuse band of light across the sky, later identified as the Milky Way.

Today, the routine of an astronomer is quite different from Galileo's. While the Italian spent entire nights observing and writing down what he saw, technology has made things easier. This is because telescopes now collect information in pre-programmed regions of the sky at the desired time. The job of many scientists, therefore, is actually to analyze the large volume of data we can obtainBut does the romantic vision of the astronomer, the lover of the universe who didn't even sleep in order to observe it, still exist? We can say it does. And the reason is amateur astronomy, very much motivated by amateur telescopes.

Telescope types

Image: NIAAS

There are mainly three types of telescopes: the refractor, the reflector and the catadioptric, also called compound or Cassegrain. In the case of the first, lenses are used to focus the image in the eyepiece, through which we observe. They are the famous lunettes, the most classical type of telescope. However, the prices may not be very friendly for tubes with diameter greater than 100 mm. The reflectors, on the other hand, areuse mirrors instead of lenses and are therefore cheaper. Maintenance has to be taken into account, however. Reflecting telescopes need to be realigned (collimated) as they are used, especially if it is common to move them around. Dust is also a problem, considering that the tubes are open. Moreover, the coating on the mirrors needs to be replaced after 10 or 20 years.In other words, reflecting telescopes guarantee a better price, but also a little bit more work.

A refracting telescope was used by Galileo and reflectors were invented by none other than Sir Isaac Newton. Catadioptrics, on the other hand, are more modern. Their design combines mirrors and lenses in an ingenious way to allow greater magnification in a smaller tube. The field of view is also larger, making it easier to observe larger objects in the sky. That is, Cassegrain are compact,powerful and practical. However, they are also more expensive.

Aperture and magnification

Image: Leo Evans

Besides the types, you have to pay attention to the size, more specifically to the so-called aperture of the telescope. In fact, it is the most important characteristic of the instrument. The diameter of the lens or main mirror determines how much light will be collected by the instrument. And the more light, the more objects and more details we can see. With a diameter of 70 to 100 mm it is already possible to see thecraters of the Moon in detail, as well as the atmospheric bands of Jupiter and the rings of Saturn. For objects such as galaxies, nebulae and clusters, however, a larger aperture may be required.

Although the aperture is most important, it is often the magnification that takes the credit. The magnification (increase or approximation) of the image depends on the distances from the focus point (or focal length) to the lens or mirror. The same goes for the focal length of the eyepiece used, which is also relevant. Having plenty of magnification in the image, however, without a good aperture, only guarantees observing theThis is because in this case the light collected is not enough for us to see in detail. And, of course, the atmospheric conditions are not always ideal.

Assembly

Image: OASI

The mounting is also important. After all, the tube cannot be suspended in the air. There are mainly two types, azimuthal (or altazimuthal) and equatorial. The first mount is simpler and works like a photographic tripod. That is it moves up and down in altitude and sideways (in azimuth). The equatorial, on the other hand, is less intuitive for beginners. There are two axes of movement, one of themaligned with the Earth's rotation, which should always be done when moving the telescope. To do this, we align the axis with the celestial south pole (or north pole, for those in the northern hemisphere).

On top of all that, it is possible to integrate the mounts with an automated system linked to a celestial database. This allows the amateur astronomer to find an object by simply pressing a few buttons. Mounts like this are called GoTo. And, of course, they also raise the final price. But it all depends on how easy you want to observe and what kind of object you want to observe, as well as thechoosing the type and size of the telescope. And not everyone knows, but it is not necessary to invest all your budget to acquire a reasonable instrument. Knowing a little about telescopes and their limits and possibilities, the sky is the limit.