The Telescope
In Venice on a holiday in 1609, Galileo Galilei heard rumors that a Dutch spectacle-maker had invented a device that made distant objects seem near at hand (at first called the spyglass and later renamed the telescope). A patent had been requested, but not yet granted, and the methods were being kept secret, since it was obviously of tremendous military value for Holland.

Such an instrument as the telescope would also be valuable to Venice, and the scientist was determined to attempt to construct his own spyglass. After a frantic 24 hours of experimentation, working only on instinct and bits of rumors, never having actually *seen* the Dutch spyglass, he built a 3-power telescope. After some refinement, he brought a 10-power telescope to Venice and demonstrated it to a highly impressed Senate. His salary was promptly raised, and he was honored with proclamations.

If he had stopped here, and become a man of wealth and leisure, he might be a mere footnote in history. Instead, a revolution started when, one fall evening, the scientist trained his telescope on an object in the sky that all people "knew" must be a perfect, smooth, polished heavenly body--the Moon. We can only imagine his astonishment on finding a surface that was "uneven, rough, full of cavities and prominences." A surface full of features much like those that could be found on Earth. This was tremendously exciting news, although there were still plenty of people who insisted that Galileo Galilei was wrong. Some of their arguments were very clever, like the mathematician who insisted that even if Galileo was seeing a rough surface on the Moon, that only meant that the entire moon had to be covered in invisible, transparent, smooth crystal.

Months passed, and his telescopes improved. On January 7, 1610, he turned his 30 power telescope towards Jupiter, and found three small, bright stars near the planet. One was off to the west, the other two were to the east, all three in a straight line. The following evening, Galileo once again took a look at Jupiter, and found that all three of the "stars" were now west of the planet, still in a straight line!

Observations over the following weeks lead Galileo to the inescapable conclusion that these small "stars" were actually small satellites that were rotating about Jupiter. If there were satellites that didn't move around the Earth, wasn't it possible that the Earth was not the center of the universe? Couldn't the Copernican idea of the Sun at the center of the solar system be correct?

Just like any modern scientist, Galileo Galilei published his findings--as a small book titled The Starry Messenger." 550 copies were published in March of 1610, to tremendous public acclaim and excitement. We can imagine what it was like for people--probably something like when people learned that the Earth was round, not flat. Or, more recently, what it was like to discover that our galaxy was only one of billions!

And there were more discoveries via the new telescope: the appearance of bumps next to the planet Saturn (Galileo thought they were companion stars; the "stars" were actually the edges of Saturn's rings), spots on the Sun's surface (though others had actually seen the spots before), and seeing Venus change from a full disk to a sliver of light.

The Vatican's Reaction
The great detective Sherlock Holmes once said that "Whether the Earth goes around the Sun or the Sun around the earth makes not a penny-worth of difference to me or my work." For Galileo Galilei, saying that the Earth went around the Sun made a huge difference, since he was contradicting the teachings of the Church. While some of the Church's mathematicians wrote that his observations were clearly correct, many members of the Church believed that he must be wrong.

In December of 1613, one of the scientist's friends told him how a powerful member of the nobility said that she could not see how his observations could be true, since they would contradict the Bible. The lady quoted a passage in Joshua where God causes the Sun to stand still and lengthen the day. How could this mean anything other than that the Sun went around the Earth?

Galileo Galilei was a religious man, and he agreed that the Bible could never be wrong. However, he said, the interpreters of the Bible could make mistakes, and it was a mistake to assume that the Bible had to be taken literally. The true meaning of a Biblical verse might not be obvious at all, and wise Church scholars would have to work hard to find the true meanings. After all, a cardinal in the Church itself had once said that the intention of the Holy Spirit is to teach us how one goes to heaven, not how heaven goes! He ended with an explanation of how the miracle could not possibly have taken place if the Sun went around the Earth.

This might have been one of Galileo's major mistakes. At that time, only Church priests were allowed to interpret the Bible, or to define God's intentions. It was absolutely unthinkable for a mere member of the public to do so.

And some of the Church clergy started responding, accusing him of heresy. One friar quoted from the New Testament "O ye men of Galilee, why stand ye gazing up into heaven?" Another churchmen went to the Inquisition, the Church court that investigated charges of heresy, and formally accused Galileo. This was a very serious matter. In 1600, a man named Giordano Bruno was convicted of being a heretic for believing that the earth moved about the Sun, and that there were many planets throughout the universe where life--living creations of God--existed. Bruno was burnt to death.

This time, Galileo was found innocent of all charges, and cautioned not to teach the Copernican system. 16 years later, all that would change.

The Final Trial
The following years saw Galileo move on to work on other projects. With his telescope he watched the movements of Jupiter's moons, wrote them up as a list, and then came up with a way to use these measurements as a navigation tool. There was even a contraption that would allow a ship captain to navigate with his hands on the wheel. That is, assuming the captain didn't mind wearing what looked like a horned helmet!

As another amusement, Galileo started writing about ocean tides. Instead of writing his arguments as a scientific paper, he found that it was much more interesting to have an imaginary conversation, or dialogue, between three fictional characters. One character, who would support Galileo's side of the argument, was brilliant. Another character would be open to either side of the argument. The final character, named Simplicio, was dogmatic and foolish, representing all of Galileo's enemies who ignored any evidence that Galileo was right. Soon, he wrote up a similar dialogue called "Dialogue on the Two Great Systems of the World." This book talked about the Copernican system.

"Dialogue" was an immediate hit with the public, but not, of course, with the Church. The pope suspected that he was the model for Simplicio. He ordered the book banned, and also ordered the scientist to appear before the Inquisition in Rome for the crime of teaching the Copernican theory after being ordered not to do so.

Galileo Galilei was 68 years old and sick. Threatened with torture, he publically confessed that he had been wrong to have said that the Earth moves around the Sun. Legend then has it that after his confession, Galileo quietly whispered "And yet, it moves."

Unlike many less famous prisoners, he was allowed to live under house arrest in his house outside of Florence. He was near one of his daughters, a nun. Until his death in 1642, he continued to investigate other areas of science. Amazingly, he even published a book on force and motion although he had been blinded by an eye infection.

The Story Continues...
The Church eventually lifted the ban on Galileo's Dialogue in 1822--by that time, it was common knowledge that the Earth was not the center of the Universe. Still later, there were statements by the Vatican Council in the early 1960's and in 1979 that implied that Galileo was pardoned, and that he had suffered at the hands of the Church. Finally, in 1992, three years after Galileo Galilei's namesake had been launched on its way to Jupiter, the Vatican formally and publicly cleared Galileo of any wrongdoing.

information provided by NASA

Other Mentions of Galileo Galilei on About.com
Sir Isaac Newton
History of the Telescope - History of Binoculars
Evangelista Torricelli
The Invention of Clocks - Mechanical and Quartz Clocks
Microscope - The Inverse Telescope

Telescopes
Early Telescopes
History of the Telescope - History of Binoculars
The Telescope
Historical Telescopes in the Netherlands

©Mary Bellis