him create the law of universal gravitation (gravity). The third rule, which he declared in the year
1618, was that all planets were proportional to the semimajor axis of its orbit. He saw the Copernium
system, and his mentor Brahe’s observations, which he found to be incorrect. Therefore, he sought to
change and refine it in order to find out how the real way the planets orbited around the sun.
Therefore, Keplar helped filled in the final piece to a million year old puzzle, by finding that the
planets orbited around ellipses and not circles, which Aristotle and Copernicus thought was the
correct orbits. He put all his theories and observations, in his 1596 book called the “Mysterium
Cosmorgraphicum” which defended the Copernican theory, as well as showed his geometric
models. For example, the Platonic Solid Model which was made to show the distances of the planets
from the sun, was in his published book. Keplar discovered many other things, for example, he found
that planets orbited faster when they came closer to the sun as well as slowed down when they went
away from the sun. In his discovery of ellipses, Kepler also wiped out Brahe’s data of the way he
thought the solar system was, and proved that his data had inaccurate information.
Other Discoveries:
Book of Astronomia Nova (1609)
 He discovered the formation of pictures in a pinhole camera.
 He dissevered refraction within the eye as well as how its vision worked.
 He created glasses which cured people of near sightedness and far sightedness.
Book of Dioptrice (1609)
 He discovered magnification as well as real inverted images.
 He was able describe how a telescope actually works.
 He explained the properties of Internal Reflection.
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Galileo Galilei:
Who was Galileo Galilei?
Galileo Galilei was an Italian physicist and astronomer, born on February 15th 1564. He was the
eldest of seven siblings, and he went to Jesuit monastery to become a monk. Unfortunately, his
father didn’t approve of this, and took him out of the monastery. He studied mathematics at the
University of Pisa at the age of 17, and by the time he was 20, he was teaching mathematics to
students inside of the university. Although Galileo was famous before the year 1609, this was due to
his creation of rudimentary thermometer, which read variations in temperatures, his invention of a
compass in 1569, that can make cannonballs be accurately aimed, and his lecture about the true
appearance of Dante’s Inferno, which impressed his audience and gave him a university of Pisa 3
year appointment, his astronomical achievements began in the year 1609. His astronomical
achievements began in that times, by hearing about a Dutch optician, who was creating a device that
can make people, see distance objects clearly. This was called the spyglass, which was changed to
name now commonly known as the telescope; therefore, this spread of information reached Galileo’s
ears, intrigued Galileo, and gave him the ambition to create his own version of the unusual spyglass.
After a day of experimenting and inventing, he came up with his own 3-powerd telescope called
Galileo’s Telescope. This telescope was redefined, by Galileo grinding his own versions of telescope
lenses. Once he was done, he took his refined 10-powered telescope with him to Venice, which
made his salary double. Galileo also created a device called a Jovilabe, which gave the positions of
Jupiter’s moons without using difficult calculation. In the year 1610, on 12th of March, he published his
findings and observations in his book called “The Starry Observer”. He made many more
astronomical discoveries, until the year 1616 where he was accused of being a heretic but was
released, and was warned not to write or talk about the Copernican theory. Unfortunately, Galileo
was imprisoned for life in his home, sixteen years after his accusation, in the year 1633, for writing a
published dialogue called “The Two Great Systems of the World” which explained about the
Copernican theory. Galileo died in 1642 due to his poor health.
What did Galilei Achieve?