Lesson 95
Here is my report on what I have learned thus far in my Astronomy course (by Daniel Dignan).
Definition of “Telescope:” far seeing
A Tiny Lecture
First, I want to explain why studying Astronomy and the Cosmos is important. Throughout history (even to this day), people have based their views on how life began as well as their opinions on theology on their understanding of the Cosmos. If we don’t understand why we are here or how life began, then what is our purpose in life?
Alright, here is a little bit of history to catch you up on how the telescope was made, the evolution of the telescope, and how problems were solved:
The Telescope
Galileo Galilei made a telescope that had a 3x magnification rate and then about two years later made another telescope 33x times the magnification rate
A telescope captures light using a primary (objective) lens which focuses the light into the telescope’s eye-piece which magnifies the image on your retina on your eye.
Light plays a huge role in our ability to see things. The reason that we can’t see far of objects like stars clearly is because the object doesn’t produce enough light.
Now, if your eye was bigger, then it would collect more light…which is exactly what a telescope does!
The first type of telescope was the refracting telescope which consisted of an objective lens, an eyepiece and a tube. The problem with this telescope (though it did work) was that the large objective lenses were hard to manufacture. The biggest and most annoying and problem was chromatic aberration, and the fact that, in an effort to fix Chromatic Aberration, they made their telescopes longer and longer, eventually resulting in ridicules lengths (hundreds of feet long!). So, what was this Chromatic Aberration? Chromatic aberration was when, due to the ineffectiveness of the lenses, you would have a rainbow/hallow effect above the object you were viewing.
The solution? Sir Isaac Newton and his reflecting telescope.
Newton deduced, from his observations, that it was absolutely impossible to fix Chromatic Aberration. This is why he created the reflecting telescope.
The reflecting telescope’s components consisted of:
1. A tube (obviously, as with the refracting telescopes)
2. A concave lens. This lens is curved. It appears as though hollowed out like a bowl. This was the first change that helped with the chromatic aberration.
3. Mirrors. These mirrors reflected the light coming off of the concave lens to the eyepiece (and thereby to the eye). The one problem with this type of telescope is that the mirrors are in the way of the oncoming light; thus, blocking at least 1% of the light from entering into the telescope. The best of these telescopes block only 1%. Most of them would block more.
As I said, the reflecting telescope was better than the current model of the refracting telescope. The problem with it was that the mirrors blocked small portions of light; slightly hindering the effectiveness of it.
Understandably, people were not completely content to be satisfied with some of their light getting blocked. Upon review of the problem of Chromatic Aberration, people found that it could be fixed with a mere tweak of the lenses. This “tweak” was called the Achromatic doublet. The Achromatic doublet used two convex lenses and one concave lens.
So, in the end, the problem of Chromatic Aberration was fixed and we had two effective telescopes.
The telescope was one of the subjects I studied this week. The next subject had to do with the Earth in general. I will start with addressing people’s ideas of how the Earth “operated.”
Earth
Currently, and for most of the modern world, people have believed that we live on a globe spinning through a vast universe which is constantly expanding. However, this was not always the case.
Back in the day, people believed that we lived on a flat plane. After all, we don’t feel the supposed powerful winds from our spinning globe, right? Contrary to current standard teaching, the Earth was the centre of the solar system and the sun, moon, and constellations revolved around them.
Similar to the fact that we don’t feel the incredibly powerful wind that would be caused by the supposed rotation of the Earth, Astronomers didn’t see something in the stars which (as was the belief at the time goes) should have proved the existence of a spinning globe; that something is called Stellar Parallax. This is the idea that as the Earth rotates, due to our different position and thus different view of the cosmos, the distance between stars and constellations changes. However, though Astronomers tried to measure a change, no change could be measured. Science today claims that Stellar Parallax can be measured and observed with special equipment. I, however, am not sold as to the validity of this.
Then came Nicholas Copernicus who published a book stating his beliefs that the Sun was in the centre of the universe and that all other planets, including the Earth, rotated around it. The Catholic Church did not endorse this idea as it was contrary to their doctrine that the Earth was in the centre of the universe.
Then along came Galileo with his telescope and the observations he made with it seemed, to him, to support the Heliocentric model. He observed how Venus’ moons orbited around it; deducing therefore that the not everything rotated around the Earth.
Then Johannes Kepler came out with his laws of planetary motion saying that planets moved in elliptical orbits instead of circular orbits (as was the common belief at the time). This belief that planets moved in ellipses did not seem to work as well with the geocentric model, so these observations were credited as proof for the Heliocentric model.
The last astronomer I will mention today is Sir Isaac Newton who presented the idea of gravity. This was pretty much the last straw for most people to give up on the geocentric model.
Present day
Currently the general populace believes in the Heliocentric model. There are, however, a large number of people who believe in a Geocentric model. The truth or falsehood of each is up to you, my readers, to research and decide about; the purpose of this essay was not to disprove either of them. It was merely to address the evolution of the views of Earth from the Heliocentric perspective.
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Land Of The Living 