What is a Telescope

What is a Telescope?

Since ancient times, humans have held fascination at the beauty of the blanket of stars that appears during the dark night. As such, astrology played a vital role in history as our ancestors often observed the movement of the skies and reflected it in their daily lives.

One of the earliest records of a tool to observe the skies was in 1608 and was used by Hans Lippershey. The tool, what we now call a telescope, was made by the Dutch glassmaker and soon exploded in popularity.

There have also been claims that the discovery of the telescope was by Zacharias Janssen, a spectacle maker in Middelburg, and Jacob Metius of Alkmaar.  Nevertheless, this tool was so popular that it even reached the ear of a renowned and genius Italian inventor, Galileo Galilei. In 1609, Galileo created his own telescope. In 1611, the telescope was given its formal name after Galileo presented his tools at a banquet of Accademia dei Lincei.

The name was coined by Giovanni Demisiani and was from the ancient Greek words tele which has the definition of “far” and skopein or “to look or see”. It created the word teleskopos which means “far-seeing”. In his Starry Messenger pamphlet, Galileo referred to his telescope as “perspicillum”.

In the same year, Johannes Kepler described how a telescope could be made with a convex objective lens and a convex eyepiece lens. Since then, refractor telescopes were the most popular type of telescope.

In 1688 Isaac Newton was credited for the first practical design of a reflector and he named it the Newtonian reflector. This Newtonian reflector is the most popular reflector model even now. As telescopes play a vital role in the study of the universe and its entities, continuous evolutions have been made.

1733 saw the invention of the achromatic lens which partially corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes.

What is a Telescope?

But what exactly is a telescope? We know that it is a tool used for the observation of the space. How do they work? To put it simply: with light. Telescopes use the facts involving light and its properties to reflect an image from outer space into the eyepiece of your tool.

When discussing telescopes, it is important to first understand the difference between a refractor and a reflector. A refractor uses a lens to gather the necessary light while reflectors use mirrors. Reflectors are cheaper compared to refractors but is not necessarily a low-end version of the refractor.

To make far objects be reflected on your telescope, there are two pieces that are involved in this process: the objective lens, or your primary mirror, and the eyepiece lens.  The objective lens (for refractors) or the primary mirror (for reflectors) collects a lot of light from a distant object and brings that light, or image, to a point or focus.

The eyepiece lens that is attached to the optical tube of your telescope takes the bright light from the focus of the objective lens or primary mirror and magnifies it to take up a large portion of the retina of your eyes.

This principle is the same working principle behind the magnifying glass. As such, combining these two lenses makes the functioning telescope. Again it is important to remember that the basic idea is to collect lots of light to form a bright image inside the telescope and use something to magnify the image until it reaches your retina.

Your telescope has two properties that it is mainly concerned with: its ability to collect light and its ability to magnify the image. The telescope’s ability to collect light is directly related to the diameter of the lens or mirror called the aperture that is used to gather the light. While its ability to magnify the image is defined by the combination of lenses used and is termed magnification.

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