Portrait of Galileo Galilei
Ottavio Leoni, Reunion des Musees Nationaux

Galileo Galilei

Galileo Galilei was an Italian astronomer and physicist who lived between 1564-1642. He challenged Aristotle's ancient proposition that heavenly bodies were divine and therefore perfect and blemish-free.

In 1609, Galileo became first person to use a telescope to look at the heavens. He discovered sunspots, and craters and peaks in Earth's moon.

The telescope also allowed Galileo to confirm the work of Copernicus in that the planets circle the Sun (as opposed to all heavenly bodies circling the Earth). Galileo's work offended the Roman Catholic Church and he was convicted of heresy in 1616 by the Inquisition. It wasn't until 1992 that Pope John Paul II announced that the Catholic Church erred in condemning Galileo's beliefs. Sentenced to house arrest for the later years of his life, Galileo is remembered as a martyr for scientific truth.


You might also be interested in:

Science, Evolution, and Creationism

How did life evolve on Earth? The answer to this question can help us understand our past and prepare for our future. Although evolution provides credible and reliable answers, polls show that many people turn away from science, seeking other explanations with which they are more comfortable....more

Aristotle

Aristotle was a Greek philosopher who lived between 384-322 B.C. He was one of the greatest thinkers of the world and his written works encompassed all major areas of thought: logic, science, metaphysics,...more

The Earth's Moon

The Earth's one natural satellite, the Moon, is more than one quarter the size of Earth itself (3,474 km diameter), making the Earth-Moon system virtually a double-planet. Because of its smaller size,...more

Nicholas Copernicus

Nicholas Copernicus was a Polish astronomer who lived between 1473-1543. He was born in Torun, Poland to a middle class family. He attended school at Cracow and eventually moved on to Italy where he received...more

Ptolemy

Ptolemy was a Greek astronomer who lived between 85-165 A.D. He put together his own ideas, those of Aristotle, and Hipparchus' system of epicycles and eccentric circles, to formulate the geocentric theory....more

Cancer

Cancer, the Crab, is a member of the Zodiac, a group of constellations that the Sun travels through each year. Cancer spends half of the year in the sky. It first rises in December and is visible through...more

Motions of the Planets

For many years, people believed that the Earth was the unmoving center of the universe and that the planets,Sun, moon, and the stars moved on spheres around the Earth. Astronomers such as Copernicus and...more

Tycho Brahe

Tycho Brahe was a Danish astronomer who lived between 1546-1601. Although Tycho had his own model of the solar system, which differed from both the heliocentric and geocentric theories, his contributions...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA