Galileo Galilei

Galileo Galilei

­ Galileo Galilei was an Italian scientist who played an instrumental role not only in the development of astronomy, but of modern science in general. He was born in Pisa in 1564 to Vincenzo Galilei, but at age 8 his family moved to Florence. He had three illegitimate children with Marina Gamba. He attended the University of Pisa and taught at the University of Padua. He died in 1642 and was buried in the Basilica of Santa Croce.

Galileo invented the horse-driven pump, the sector, the pendulum clock, and the thermoscope, a precursor to the modern thermometer.  However, his most important contribution was improving Hans Lippershey’s telescope. Lippershey is credited with inventing the telescope by lining up two convex lenses, but it only had a magnification of 3x. Galileo studied Lippershey’s schematic and built one with 30x magnification, which he sold to sailors and merchants. The telescope dramatically increased the empirical potential of astronomy; with it, the observer can see much more of the sky, but it also links the observation to an apparatus, which is much more consistent and trustworthy than the human brain.

Armed with the telescope, Galileo made numerous keen observations of the skies. For centuries, people had tried to explain away the spots on the Moon in a misguided attempt to preserve celestial perfection. Galileo observed that the amount of shading in these lunar spots varied with its angle to the Sun as if they were indentations. He thus discovered that the lunar surface has mountains and valleys, upending the expectation that celestial bodies had to be flawless. Galileo also proposed the concept of librations, which are slight movements of the Moon relative to the Earth that allow us to see it from different angles.

Galileo was the first person to definitively observe sunspots. Prior attempts dismissed the spots as a transit of Mercury. The major obstacle to overcome was being able to observe the sun without eye damage, which Galileo circumvented by observing the Sun through a telescope. He shared his observations of sunspots in 1911 but had a long feud with Christoph Scheiner over the explanation of the black spots. Scheiner claimed that there were objects with orbits very close to the Sun that were only visible at inferior conjunction. The debate was settled by David Fabricius, who showed that they were sunspots, not orbiting bodies.

Galileo was the first person to observe Jupiter’s four largest moons. He initially noticed what looked like 3 fixed stars in a line next to Jupiter, but after multiple sessions, it became clear that there were actually 4 objects and they were orbiting Jupiter. This discovery gave credence to the Copernican, heliocentric view: since Jupiter’s moons are not orbiting the Earth, Earth cannot be the center of all celestial motion.

Galileo was the first to observe the rings of Saturn. At first, he thought he was observing a tri-star formation, with two ancillary stars on either side of Saturn. However, he later observed that the lateral stars disappeared, a stymying realization. Not until 1858 did James Maxwell publish a mathematical analysis of these “stars” and show that they were rings made of many minuscule particles.

Galileo’s importance to the field of astronomy is inestimable. Modifying the telescope gave him the superior accuracy necessary to observe the rough lunar surface, sunspots, Jupiter’s moons, and Saturn’s rings.

Works Cited

1. "Galilei, Galileo (1564-1642)." World of Earth Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Vol. 1. Detroit: Gale, 2003. 243-245. Gale Virtual Reference Library. Web. 1 Oct. 2010.

2. "Galileo Galilei." Wikipedia, the Free Encyclopedia. Web. 11 Oct. 2010. <http://en.wikipedia.org/wiki/Galileo_Galilei>.

3. Hightower, Paul. Galileo: Astronomer and Physicist. Springfield, NJ, USA: Enslow, 1997. Print.

4. "Science." The Galileo Project. Web. 11 Oct. 2010. <http://galileo.rice.edu/science.html>.