Week One of Astronomy

The first week of this astronomy section I learned about the history of astronomy and telescopes.

The History of Telescopes

The first telescope ever made was made in 1609, by a man named Galileo Galilei; this telescope was named “far seeing” when it’s name is translated into English. The telescope was a refractive telescope; which means that the telescope has an objective lens on one end and an eyepiece on the other.

The first telescope’s objective lens was convex, and the eyepiece was concave. This was problematic because the way the objective lens channels colors creates a “rainbow halo”, this causes a distorted view when looking through the telescope. This problem is known as chromatic aberration. To help prevent this problem the people who built the telescopes would make the telescopes bigger and longer, some of these long telescopes were up to one hundred feet long!

Eventually people began to build the telescope’s objective lens in a way that used the convex and concave lenses together, fixing the issue chromatic aberration, and making the colors more focused. This way of building the objective lens is known as “achromatic doublet”.

But before achromatic doublet was around to fix the problem of chromatic aberration. Sir Issac Newton got so frustrated when trying to fix the refractive telescope that he decided that the problem of chromatic aberration was unfixable, so he created a different kind of telescope. The telescope he made was reflective, which meant that it used mirrors instead of the regular lenses. This made it easier to see through since the mirrors reflects the light toward the eye.

History of Astronomy

The field of Astronomy began thanks to Greek and Roman philosophers and scientists, one of the first was Ptolemy. He created a geometric theory on the way the planets including the sun moved around the earth. Frankly his theory was incorrect, but the Catholic Church still used it as the official doctrine.

This theory was proven incorrect by an astronomer named Nicolas Copernicus in 1543, who created the heliocentric theory (which is the theory of how the planets and the earth included move around the sun), in a book that was published the same year he died.

Over the years the heliocentric theory was proven to be the correct one out of the two theories.