Comment utiliser un télescope (pour les débutants) et devenir astronome

15 Juil 2018

OSR blog post

Le télescope est un instrument d’optique qui utilise un procédé assez simple qui permet d’observer le ciel en augmentant la taille apparente et la luminosité d’un objet très loin situé dans l univers.

This instrument is no longer used only by astronomers and professionals in the field, looking at the stars has become a passion for many people who are increasingly interested in the fascinating world of stars. Indeed, observing celestial bodies like galaxies, bright stars and planets provides an exceptional feeling and tremendous excitement.

Acquiring the telescope:

Before purchasing your own telescope, you must first identify the type of telescope you will need depending on the nature of the observations you wish to make. You can choose between 3 types of telescopes:

  • The refractor: also called a telescopic telescope, is an instrument that allows you to observe the planets and the Moon with a clear, good quality image. It is easy to transport and does not require too much maintenance, however it does not allow observing faint celestial bodies such as galaxies.
  • The reflector telescope: this type of telescope offers good visibility and is suitable for beginners. However, its optical system tends to capture the condensation of water vapor, something which could disrupt views during observations. In addition, it is not suitable for observing terrestrial objects.
  • The catadioptric telescope: is a mixed telescope which combines the two techniques used by the two previous telescopes. This instrument is easier to transport and is well suited for astrophotography. It can perform several functions, but it costs more than other types of telescope.

The power of the telescope you choose should depend on the location from which you will observe, the degree of light pollution and the frequency of rain. For example, if you want to make observations from a place with heavy nighttime dew, opt for an astronomical telescope or a catadioptric telescope. People tend to believe that a high-power telescope always means high resolution and better image quality, but this is not always obvious. High power reduces the brightness of the observed bodies and gives a blurred image.

Know how to handle the telescope:

The telescope finderscope: this accessory is generally attached to the side of the telescope. It allows you to see a part of the sky larger than the size of the telescope by magnifying the size of the image provided by the latter.

The telescope mount: there are two types of mounts, equatorial mounts and azimuthal mounts.

  • The equatorial mount: An equatorial mount rotates around two axes, the polar axis and the declination axis. The polar axis represents the mobile part placed at the base of the telescope which is oriented towards the Polar Star or the north. Thus, the telescope will move between east and west to follow the movement of the stars. Using this mount can be difficult, because to change the observation target, you have to loosen the mount to be able to adjust your aim using the finder, then tighten it again.
  • An altazimuth mount: this is a mount that is easy to handle as it is generally equipped with a motor which allows a beginner to follow a celestial object by easily guiding the telescope. Using this type of telescope is simpler than using a telescope equipped with an equatorial mount.

When installing the telescope, make sure that the tripod that supports it is well placed and balanced to avoid a fall which could cause damage to your instrument. To choose your observation site, make sure that the ground is horizontal to make it easier to install your telescope.

Start observing the sky!

First start by identifying the celestial objects you want to observe. You must carefully choose the observation location, time and atmospheric characteristics. For example, you should avoid the full Moon when you want to observe the stars because the vision will not be very clear. Read books on celestial objects and examine sky maps to have a clearer idea of ​​observation times, planets to observe and, above all, know in which direction to point your telescope.

If you want to benefit from clear visibility and good image quality, you will need to choose the right time which will allow you to practice in optimal weather conditions. Indeed, light pollution is an element that must be avoided during astronomical observation, try to find a place that is far from city lights for example. It is best to observe the sky when it is completely clear, and when the wind is very light.

It is best to practice setting up and using your telescope in advance. Because it’s easy to train during the day while you’re at home, so you can do it more easily at night. Also take advantage of daylight to check that the finder’s pointers are aimed at the same point. To check alignment, aim at an object that is about 30 meters or more away. The finder must be adjusted correctly, as this is essential to being able to locate celestial bodies.

During the observation, you will notice that depending on the eyepiece used, the Moon leaves your field of vision more or less quickly. Indeed, the more you zoom in, the more the effect of the earth’s rotation is amplified. So use the automatic tracking motor or correct the earth’s rotation using the right ascension axis tracking hose.

Attention !

The most important thing and which should never be forgotten is that you should never point your telescope towards the sun even when using a solar filter, because if the glass cracks, you are at high risk of losing your sight. .