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Galileo Galilei invented two important instruments. The first was the calculating compass, which helped solve math problems. The second was a greatly improved telescope, which was first invented by Hans Lipershy of the Netherlands in 1608. With the improved telescope, Galileo discovered many new things about outer space.

Young Life

Galileo was born on February 15, 1564 in Pisa, Italy. He went to college at the University of Pisa where he studied medicine and the philosophy of Aristotle. The philosophy of Aristotle was that the earth is round. This inspired Galileo to prove other theories about the earth and outer space. After college, Galileo spent four years as a math tutor. In 1592, he was given a job at the University of Pisa. For the next 18 years, Galileo worked as a math professor.

Telescope

During this time in 1608 Hans Lippershey from the Netherlands invented a spyglass, which could be used to see objects as far as two miles away. This spyglass was a tube that had a glass lens on each end. When Galileo heard the news about Lippershey’s spyglass he knew that with his knowledge he could improve the spyglass and that’s exactly what he did. Some improvements Galileo made to the spyglass were to have one tube fit inside a bigger tube so you could slide them forwards and backwards. This allowed him to change the focus of the lenses. Galileo also experimented with changing the curve and size of the lenses so you could see further. These first experiments and calculations resulted in his first spyglass. The two hollow metal tubes, one inside the other, had one convex lens on the end (a convex lens has sides that are bowed outward) and the other tube had a concave lens on the end (a concave lens is a lens that has its sides curved in.) This first spyglass was a success and he named it a "telescope" for the Greek words "tele" meaning "far" and "scopein" meaning "see." His telescope was better than Lipershy’s because Galileo’s telescope magnified things almost 15 times more and was much larger than Lippershey’s.

Discoveries With The New Telescope

Galileo was the first person to use his new telescope. Galileo made many discoveries with his telescope. He discovered that the moon had mountains and was pitted much like the earth is. He learned that like the moon the planets all have phases. (Phases are the stages that the moon goes through - from full to new and back again.) He paid very close attention to the phases of Venus more than those of any other planets. He also found out a lot about Jupiter. One night while looking through his telescope he saw four moons orbiting (circling) Jupiter. He called these four moons the Medicean Planets. He named them after the Medicis who at that time were the ruling family of Florence, Italy. Another thing he found with his telescope were the four biggest satellites (moons) of Jupiter. Galileo also discovered sunspots, lunar mountains, and lunar valleys through his telescope. Galileo realized one night that the Milky Way (the earth’s galaxy) was made up of millions of stars. As you can see, Galileo‘s telescope was very useful to him and others who used it. Telescopes were important to study outer space because there was no other way to study outer space at that time.

His First Invention

Before the he improved the telescope Galileo invented a calculating compass to help his math students solve math problems. He called it a calculating "compass" because it looked like a compass. This greatly helped Galileo when he taught at the University of Pisa.

Galileo’s Books

Galileo wrote three books after all these fine and very interesting discoveries. His first book was about floating bodies, which documents the idea that explains why the water level in a swimming pool rises and why you feel lighter when you jump in. His second book was about theories of Copernicus and Ptolemy. Copernicus’s theory is that the earth rotates on its axis, wobbling like a top, and revolves yearly around the sun. Ptolemy’s theory was that the earth, which did not move, was the center of the universe and planets, the sun, and the moon all revolved around it. The third book was called Dialogue on the Two Chief World Systems. This book was printed in 1630 and was published in 1632. A few months before this last book was published, Galileo became blind and therefore, he couldn’t continue making discoveries and writing about them. Then, in 1642 in Arcetri, near Florence, Italy, Galileo died at the age of 78.

Galileo’s new and improved telescope helped Isaac Newton continue Galileo’s work after Galileo died. Telescopes are more useful now because they allow you to see even farther into outer space and allow us to study planets without going up in space. Galileo could see the planets through his telescopes but he didn’t see them in much detail as we do today. Telescopes continue to be improved today and these improvements may help Galileo’s idea that there is no end to how far you can see with a telescope. Telescopes may be better now, but Galileo helped get it started.

Galileo Timeline

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