The Beginnings of the Telescope

This animated essay from the NOVA Web site examines the design of Galileo's refracting telescope and Sir Isaac Newton's reflecting telescope.

Galileo: Discovering Jupiter's Moons

This video segment adapted from NOVA shows how Galileo, using his newly developed refracting telescope, observed four of Jupiter's moons, the first astronomical bodies to be discovered since ancient times.

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Galileo: His Place in Science

Einstein called Galileo the "father of modern physics." This media-rich essay from the NOVA Web site looks at Galileo's quest to understand the mathematics of motion.

Galileo on the Moon

Watch Apollo 15 astronaut David Scott perform Galileo's falling objects experiment on the Moon in this video segment from NASA.

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Galileo's Big Mistake

Scientists don't always get it right. This video segment adapted from NOVA looks at Galileo's failed theory for the motion of the tides.

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Galileo's Thought Experiment

How can Earth move through space without our feeling its motion? This video segment adapted from NOVA answers this question by dramatizing one of Galileo's thought experiments.

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Galileo: Sun-Centered System

In the early 1600s, most people believed that the Sun revolved around a stationary Earth. This video segment adapted from NOVA tells how Galileo proved that the Sun, not Earth, is at the center of our universe.

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Galileo: Sunspots

This video segment adapted from NOVA shows how Galileo used his telescope to carefully observe and study sunspots.

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Galileo: Timeline of His Life

This illustrated timeline from the NOVA Web site turns back the clock to the late 1500's to relive the dramatic life of one of the world's most renowned scientists.

Gravity and the Expanding Universe

This video segment, adapted from NOVA, traces the evolving history of theories about gravity and a force that may oppose it, along with our understanding of the impact of both of these forces on our expanding universe.

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How Big Is Our Universe?

This interactive resource from Harvard Smithsonian Center for Astrophysics uses images and activities to understand the scope and scale of our universe. Featured are technologies used by generations of explorers.

Hubble's Expanding Universe

This adapted video segment, using footage from NOVA and NASA, examines Edwin Hubble's work and how his findings laid the foundation for the Big Bang theory.

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More on Galileo's Big Mistake

Even great scientists make mistakes! This illustrated essay from the NOVA Web site looks at Galileo's theory of the tides, which, while well thought out, was wrong.

Relativity and the Cosmos

This illustrated essay from the NOVA Web site introduces the basic concepts of Einstein's General Theory of Relativity and what we know about cosmology as a result.

Robotic Exploration of Space Timeline

This interactive timeline from NASA journeys through the last century, detailing key discoveries, experiments, missions, and other events that brought robotic space exploration from science fiction to reality.

What Is a Planet?

This video segment, adapted from NOVA scienceNOW, presents the ongoing debate over the definition of a planet, including the status of Pluto.

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