Cosmic Horizons

Case Study: John Michell And Black Holes

Online Resource, Article

Case Study: John Michell And Black Holes

Imagine gravity so strong that even light is contained by its force. When a country parson first described black holes in 1783, the concept was so ahead of its time that it was mostly ignored.

Case Study: Fossil Microbes on Mars?

Online Resource, Article

Case Study: Fossil Microbes on Mars?

A meteorite that escaped from Mars 16 million years ago was found recently in Antarctica. Does it, or doesn't it, hold evidence that proves the existence of life on the red planet?

Case Study: Neutrino Observatories

Online Resource, Article

Case Study: Neutrino Observatories

Update your image of astronomers. Today they spend most of their time peering into computer screens rather than through the eyepiece of a telescope. Learn what this new vantage point has gained them.

Case Study: The Cosmic Microwave Background Radiation

Online Resource, Article

Case Study: The Cosmic Microwave Background Radiation

At this distance in time and space, can we prove that the universe was created with a single explosion? See how scientists have detected a faint remnant glow that supports the Big Bang theory.

Profile: Ernst Chladni and Rocks from the Sky

Online Resource, Article

Profile: Ernst Chladni and Rocks from the Sky

Today, we accept the notion that enormous rocks exist within our solar system and that some of them fall to Earth. A little over 200 years ago, though, this idea garnered skepticism and ridicule.

Profile: Georges Lemaître, Father of the Big Bang

Online Resource, Article

Profile: Georges Lemaître, Father of the Big Bang

When a Catholic priest—cosmologist first proposed that the universe began as a "primeval atom," it seemed preposterous. Yet, within a few years, his theory had helped revolutionize cosmology.

Profile: Ole Roemer and the Speed of Light

Online Resource, Article

Profile: Ole Roemer and the Speed of Light

While studying one of Jupiter's moons, Ole Roemer happened upon the first good estimate of the speed of light. Before his 1676 discovery, scientists assumed that light could not be measured.

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