What is a Telescope?

Far from being a science only for the wealthy inventors, or only for the biggest constructions, we live in a truly blessed period of human discovery where every one can share in the wonder of the heavens. You can very easily take advantage of the inventors who have gone before us and establish your own astronomy capability in your own home. For a relatively modest cost, you can set up your very own telescope in your own backyard and experience the awesome ability to see deep into our solar system and beyond. Even children can wonder at the stars using modest and easily affordable telescopes.

Let’s first discover how the technology of telescopes has improved to the point where it is now possible for all of us to share the wonders of modern astronomy.

The design and invention of the earliest telescopes went hand in hand with the early study of optical physics, and Robert Grosseteste described it like this (in my own words):

“If we understand the science of optics, we can learn how to see

objects from a long way away seem to be close, but at the same time,

large objects can be made to look very small…

And as Robert so clearly described, we had the essential elements of what we now know as the Telescope! However, that name was not yet known, and indeed the device that we recognize today did not really have any practical utilization at that early time. So we move forward a couple of hundred years!

It was not until Giambattista della Porta described a magnifying scope when he said,” I can make a lens that can see objects a long way in the distance” which I will paraphrase this way:

A Concave shaped glass lets you see distant objects more closely.

A Convex shaped glass makes things seem smaller.

When you put them together, you get the benefit of both magnifications and focus.

 light path in a telescope

The first telescopes

The invention of the very first telescopes was by the Dutch in the early 1600s, but no one is entirely sure who was the original inventor, as the honor was claimed by several individuals all at around the same time.   The early discovery of the telescope was not without controversy, as many inventors claimed to have made the initial breakthrough.  Hans Lippershey and Zaccharias Janssen were spectacle makers who were using their craft to design components of telescopes, as well as Metius, all of whom were from the Netherlands.

However, it was Hans Lippershey who attained the first patent for the invention which became known as the telescope, which in his words could be used for:

“.. observing distant objects up close.. “

 

This proved to be financially rewarding for Lippershey, and he went on to commercialise his design, which offered all of 3 times magnification, and an upside down image!  This did not hinder the popularity of this early design of the telescope, and the instrument was made and sold all around Europe.

It was not until Galileo applied his powers of design and invention that these early limitations of power and focus were overcome.  Galileo made improvements to the design of telescopes that allowed him to increase magnification by an incredible 33 times.  This was a quantum leap in technology which allowed astronomers to study the planets and the Moon in much more detail than ever before.

 

Not only was Galileo responsible for exploring space, but his invention was the first time it was called by its modern name.  The name comes from the Greek language with ‘tele’ meaning far and skope meaning ‘to see’ hence the word telescope gives us the meaning ‘to see far’.

Despite the fact that these enormous achievements came some time after the original invention, it was the incredible make over of the instrument by Galileo that overshadowed the early designer. Because of the point of difference of the new device it became known as the Galileo telescope (Galilean) as a differentiation from the original telescope made by Lippershey.

In a very real way, these early discoveries formed the “enabling research” for the later developments. Although many different inventors and explorers were involved in each of these discoveries, the rate of technology advancement meant that bigger and better instruments were constantly being produced, and consequently, newer discoveries and better applications for the devices moved ahead very rapidly.

In some ways, we can see that the invention and design of the telescope was responsible for the very earliest race to explore space, a journey that is still being explored to this day!\

 

Technology Advancements

Refracting telescopes

But the evolution of the telescope did not stop there.  Johannes Kepler came up with a new invention of a telescope made with two convex glasses put together.  However, this technology was not properly realized until William Gascoigne took the idea another step further, and hence retained the name “Keplerian telescope”. It was not till much later that Kepler’s telescope found popularity, due to its clear and bright images.  Once again an advance in the technology was utilized by others in the field to a better and wider application, for the benefit of modern astronomers.

 

Aerial telescopes

The next amazing development was the fact that no optical tube was needed to reflect the image. The objective was sited on top of a tall structure and aimed by whatever means possible. The focussing glass was hand held or mounted at eye level, and hence these designs became known as aerial telescopes. Huge telescopes were invented, but telescopes of these long focal length were very difficult to maintain focus.

 

Reflecting telescopes

Isaac Newton discovered that the imperfections with a refractor telescope were because of the lens variations and the nature of light due to imperfections in the glass.  Newton worked out that new technology was the way to overcome the problems. Newton showed that mirrored glass was easier to avoid the imperfections of glass lenses.

To prove his theory, he built a device based on reflecting mirror technology, and made the first functional reflector telescope, and invented a whole new branch of scientific exploration to become possible to astronomers.

telescope2

https://en.wikipedia.org/wiki/File:NewtonsTelescopeReplica.jpg

 

Every time the technology boundaries were expanded, the scientific explorations expanded even further.  And that is exactly what happened when Isaac Newton arrived with his new invention of the reflector style telescope.  The reflector telescope allowed an increased aperture size, which allowed the magnification of more light and more distant objects.  The reflector telescopes just grew larger and larger until they became incorporated into the very structure of buildings, which were needed to support their massive growth.

These buildings became known by the name “Observatory” and the science of astronomy really began to take off!  These massive telescopes made the exploration of deep space more possible than ever before, and our understanding of the galaxies and of the universe sparked off new research fields in physics, optics and even to the exploration of new and incredible fields such as astro-physics and the quantum mechanics, which are still at the cutting edge of human development.

Now we can understand why the invention of the humble telescope was so exciting to early scientists and astronomers, but most of all, is still extremely exciting to those of us who enjoy studying the stars and the planets, and maybe even making a discovery of our own one day!

 

Large reflecting telescopes

Newer technology found a method of attaching a thin coating of shiny metal on glass telescope mirrors. The metallic coating was very reflective and was a better optical surface than previously used.  This discovery enabled the invention of huge glass mirrors which could be accurately machined and adequately supported.

And this brings us into the modern day technology, where we can now construct massive reflecting telescopes which are designed especially for accurate imagery of deep space.

 

Summary

Now I know that technology has not stopped at this point, but hopefully your interest has been stirred by this brief description of the evolution of the telescope, but remember there are many more interesting technologies for you to explore. Such as the incredible advancement of the Hubble Telescope with its eyes in space, Radio Telescopes with their much deeper quest into space and yet more devices which utilize other bandwidths of the electro-magnetic spectrum and are not merely limited to the visual evidence.

Far from being a science only for the wealth inventors, or only for the biggest constructions, we live in a truly blessed period of human discovery where every one can share in the wonder of the heavens. You can very easily take advantage of the inventors who have gone before us and establish your own astronomy capability in your own home. For a relatively modest cast, you can set up your very own telescope in your own backyard and have the awesome ability to see deep into our solar system and beyond. Even children can wonder at the stars using inexpensive and easily portable telescopes.

Happy star gazing!

 

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