Birth of a Supernova, Type Ia

In this interactive activity from NOVA Online, learn about a type of exploding star — a Type Ia supernova — that is so bright that astronomers can measure the distance to the galaxy in which it resides, and even learn which elements make up the star.

Birth of a Supernova, Type II

In this interactive activity from NOVA Online, learn about a type of exploding star — a Type II supernova — that is so large it has a mass 10 times greater than the mass of our Sun.

Evidence for the Big Bang Theory

This video segment adapted from NOVA tells the story of two scientists who inadvertently discovered microwave radiation that is now believed to be heat left over from the Big Bang.

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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.

How Big Is the Universe?

In this media-rich essay from the NOVA Web site, astronomer Brent Tully of the University of Hawaiʻi walks you through the latest scientific theories about the size of the universe.

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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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.

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.

Stellar Velocity: The Doppler Effect

This interactive activity from the NOVA Web site illustrates the Doppler effect and shows how it applies to measuring the direction and speed of stellar objects.

WMAP: "Baby Picture" of the Universe

View the Wilkinson Microwave Anisotropy Probe (WMAP) image from NASA to see the first detailed map of the oldest light in the universe, from 379,000 years after the Big Bang, over 13 billion years ago. A second image offers a visual timeline to put the WMAP image in perspective.