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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Hubble Telescope: Looking Deep

This video segment adapted from the Space Telescope Science Institute shows what the Hubble telescope found when it stared at a single, nearly empty spot in the sky for 10 days in 1995. The unexpected result was a picture of a multitude of galaxies stretching into the distance.

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Monster Black Hole in Galaxy M84

This animation by Thomas Goertel of the Space Telescope Science Institute is an artist's conception of a spiral galaxy harboring a super-massive black hole. Observe how the material rotates faster the closer it is to the nucleus.

The Search for Another Earth

This NASA video provides an overview of technology under development to explore the planets and stars outside our solar system. These will be the most sensitive instruments built to date.

Solar Wind's Effect on Earth

This video segment adapted from NASA describes solar storms and their effects on Earth. Animations of coronal mass ejections and solar cycles help explain what we know, and what we can predict, about solar activity.

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Total Solar Eclipse Animation

This brief animation adapted from NOVA illustrates how total solar eclipses form and explains the stages from first contact to totality.

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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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Why Doesn't the Moon Fall Down?

In this animated video segment adapted from NASA, astronomer Doris Daou explains how the forces of speed and gravity keep the Moon in a constant orbit around Earth.

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