365DaysDate: February 15, 2009


Title: The Life and Achievements of Galileo Galilei

Podcaster: Ted Haulley

Description: A short biography of Galileo, discussing some of the accomplishments that have made some call him the “Father of Modern Science.”  The main focus will be his writings on heliocentrism and conflicts with the Roman Catholic Church, but his personal life and contributions outside of astronomy will also be covered.

Bio: A native of Los Angeles, Haulley would regularly go to Griffith Park Observatory as a child in the 1970s.  After lurking for several years on the edges of show business, he spent almost 10 years in the US Navy as an air traffic controller.  He is still in the Navy Reserves, and have gone back to school with the final goal of becoming a teacher.  He lives in Waldorf, Maryland with his wife Tammie and daughter Tanda.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by the American Association of Variable Star Observers, the world’s leader in variable star data and information, bringing professional and amateur astronomers together to observe and analyze variable stars, and promoting research and education using variable star data. Visit the AAVSO on the web at


In case you don’t know the significance of the International Year of Astronomy, it is the 400th anniversary of Galileo making his first telescope and pointing skyward. So it’s only fair that hear a lot about Galileo on this podcast. Today is February 15, which is Galileo’s birthday, so Happy Birthday Galileo. Let’s celebrate by taking a quick look at his life and some of his accomplishments.
[Music intro]

Galileo Galilei was born in Pisa, Italy on February 15, 1564. His father was Vincenzio Galilei, an accomplished musician and music theorist. That’s one of his compositions playing in the background.
Galileo began studying in monastery in 1578 and considered joining the priesthood. He studied with the monks until entering University of Pisa as a medical student in 1581.

He was not really interested in medicine and became attracted to mathematics. He left the University in 1585 without a degree and began teaching and studying math in Florence. He showed interest in mechanics, geometry, gravity and motion, but showed little interest in astronomy.

In 1589 Galileo was back at the University of Pisa as chair of mathematics. It was during this time that he allegedly performed the experiment off the Leaning Tower of Pisa, showing that two rocks of different weights fall at the same speed, which challenged accepted Physics.

When his father died in 1592, he saw that he had little future in Pisa, so he moved on to the chair of mathematics at Padua, where he gave instruction on math, fortification, military engineering and mechanics.

In August 1597 he received a copy of Johannes Kepler’s first book, that supported the Copernican model of the solar system that says that the Sun is in the center and the Earth and the other planets revolve around the sun. The accepted model was Ptolemy’s, that the Earth was the center and unmoving, the sun and planets rotating around it. Galileo began corresponding with Kepler, expressing sympathy with the Copernican model. Kepler responded, asking him to support Copernicus openly, but nothing became of it. Still at this point, Galileo’s interest in planetary motion was more mechanical than astronomical.
Also in 1597 he began selling the proportional compass. He took a device that already existed that had limited use, improved it, and turned it into a multi-use instrument of great practical value for engineers and the military. He would repeat this pattern again a decade later with the telescope.

Galileo himself never married, but had three children with his mistress. The eldest daughter, Virginia, entered a nunnery and took the name Maria Celeste. She became a confidant and a bright spot in Galileo’s life.

Galileo was said to anger quickly, but was easily calmed. He was an excellent speaker and teacher, and had a lot of friends in high places. One thing that can be said about Galileo is that he did not suffer fools gladly, and he had a tendency to think that anyone who disagreed with him was a fool. This attitude would get him in trouble many times, most famously of course, with the Catholic Church.

As I said, It was 400 years ago in 1609 that Galileo first used a telescope. It is a common misconception that Galileo invented the telescope, but he did not. A Dutchman named Hans Lipperhey is credited with inventing the telescope a year earlier. But when Galileo heard about it, he immediately went about duplicating and improving it. His first telescope was 9 power, and he eventually constructed a thirty power telescope. When he turned these higher powered instruments to the skies, the perception of the universe was changed forever.

Galileo’s discoveries convinced him the Ptolemaic model of the solar system was incorrect, and that the Copernican model was the correct one. But the Catholic Church ruled in 1616 that the Copernican model was incompatible with biblical teaching, and issued an edict banning even the mention of the Copernican view.

Galileo thought he had the smoking gun. Tides. Ocean tides proved the earth moved. The double motion of the Earth rotating on its axis and revolving around the earth explains tides better than any other theory. When Urban VIII became pope in 1624, Galileo attempted to get the edict banning the defense of the Copernican system removed. The edict stayed, but he was allowed to write an impartial comparison of the two conflicting systems. Pope Urban just required that Galileo put in the popes personal favorite ‘proof’ of a fixed earth. That God is all-powerful, and could easily create any effect without any other physical explanation, or even in defiance of apparent physical explanations. Galileo himself was a devout Catholic, but thought the church should stay out of matters of science.
Galileo spent six years writing this book. The completed version was called ‘Dialogue Concerning the two Chief World systems- Copernican and Ptolemaic.’ It was written as a four day discussion between a supporter of Copernicus, Salviatti, and a supporter of Ptolemy, Simplicio, who are both attempting to persuade an educated neutral third party, Sagredo.

It was supposed to be a balanced discussion, but Salviatti was having a battle of wits with an unarmed man. Salviatti spelled out his points clearly, and backed them up with scientific discussion. He outlined galileo’s proof of motion of the Earth through tides Simplicio weakly rehashes old arguments, and does not attempt to provide scientific discussion. His last argument was Pope urban’s own proof, which made it sound like an act of pure desperation. In the end, the two sides agreed to disagree, but there is no doubt who the reader was supposed to recognize as the winner.

There is only one problem with Galileo’s tides argument. It’s wrong. Yes, the earth moves, but tides are not caused by the earth’s motion. Ironically, he specifically dismisses Kepler’s theory that the moon was the cause of tides, which was fundamentally correct, but incomplete. He also rejected Kepler’s idea that planetary orbits are ellipses, not perfect circles. Galileo was wrong on that point as well.

The book finally appeared in 1632, but when the Church got word of the book, they ordered the publication stopped, and ordered Galileo to stand trial.

He was bedridden, and had a doctor’s note that said traveling in winter might prove fatal. The church threatened to bring him in shackles if he did not appear.

In April 1633, Galileo was put on trial on charges of heresy. He didn’t stand a chance. The pope was in a vindictive mood, and the church provided some dubious evidence that proved that Galileo was guilty of heresy.

He was convicted and sentenced to life imprisonment. The dialogue was placed on the index of banned books, and he was required to publically recant any support of the Copernican system.

It was at this point that he supposedly rose to his feet and uttered under his breath “And yet, it moves.” Historians are pretty sure that he never said this. For one thing Galileo didn’t speak English. But it is also unlikely he said the equivalent “Eppur si muove,” either.

His sentence was commuted to permanent house arrest, but he church remained vindictive. First living in Sienna, the church feared that his guard was not treating him properly (as In too nice, not too harsh) he was moved. HE wanted to return to Florence, to be close to his daughter mary celeste.

He was finally allowed to return to Florence, but Mary Celeste soon got ill and passed away. Galileo lost all interest in work, and in life itself. He finally found the will to complete a manuscript about motion that he had been working on periodically for a number of years. He had troubles getting it published, and when it was finally published in 1638, Galileo was completely blind.

Discourses and Mathematical Demonstrations Concerning Two new sciences, which is nowadays shortened to ‘Two New Sciences’ was also written in dialogue form, with the same three folks from his more notorious dialogue. It was not nearly as confrontational as his other dialogue. It contained four dialogues about engineering, motion, kinematics, the nature of experimenting, and several other topics. It contains the basis for modern physics. He felt that all motion had a mathematical formula that can be tested.

In the final years of his life, the Pope remained vindictive, not allowing him to attend Easter mass, or consult doctors about his failing eyesight. Galileo died on January 8, 1642, at the age of 77. Even then the vindictiveness continued. He was buried at Santa Croce in Florence, but it took almost a century for him to receive a monument and a suitable tomb.

Galileo published books in Italian, in a time when most scholarly works were published in Latin. This increased his influence on science in Italy, but reduced it elsewhere, and his immediate impact on science outside of Italy was minimal. Isaac Newton, for example, was aware of his work, but apparently did not read it before publishing his own work about gravity and motion.

Galileo’s legacy continues today. From spacecraft to international years of astronomy, people still honor the man called the “Father of Modern Science,” “Father of Modern Physics,” and the “Father of Modern Astronomy,”

Please let me know what you think of this podcast. Tell me if you liked it, if you didn’t like it, or just complain about my poor Italian. Email me at that’s t – h – a – u – l – l – e – y at yahoo dot com. It will be nice to get some emails that are not from Nigerian banks or selling cheap Viagra. Thank you.

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365 Days of Astronomy
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