Cosmic Horizons

Article Case Study: Friedrich Bessel and the Companion of Sirius Discovering Sirius B long before technology allowed us to see it, or quantum mechanics explained the nature of white dwarfs. Article Case Study: Gerard Kuiper and the Trans-Neptunian Comet Belt A dusty snowball orbiting the Sun, trailing gas and dust as it melts: find out how these solar snowballs came to be. Article Case Study: John Michell and Black Holes When a country parson first described black holes in 1783, the concept was so ahead of its time it was mostly ignored. Article Case Study: Fossil Microbes on Mars? A meteorite that escaped from Mars 16 million years ago was found in Antarctica. Is it evidence of life on the red planet? Article Case Study: Neutrino Observatories How do scientists detect neutrinos? Today they're more likely to stare at a screen than peer through a telescope. Article Case Study: The Cosmic Microwave Background Radiation See how scientists detected a faint remnant glow that supports the Big Bang theory. Article Profile: Ernst Chladni and Rocks from the Sky The notion that enormous rocks exist within our solar system—and that some fall to Earth—once garnered ridicule. Article Profile: Georges Lemaître, Father of the Big Bang When a Catholic priest and cosmologist first proposed that the universe began as a "primeval atom," it seemed preposterous. Article Profile: Cecilia Payne and the Composition of the Stars What are the stars made of? At 25, Cecilia Payne answered this fundamental question in her Ph.D. thesis. Article Profile: Ole Roemer and the Speed of Light Before Ole Roemer's 1676 discovery, scientists assumed that light could not be measured. Article Profile: Vera Rubin and Dark Matter Vera Rubin proposed that for every visible star in the observable universe, there are nine other invisible masses. Article Profile: Carl Sagan and the Quest for Life in the Universe From television and films to professional journals and best-selling books, Carl Sagan's influence was legendary. Article Profile: Lyman Spitzer and the Space Telescope The idea of launching a telescope into orbit was first suggested in 1923, but the idea wasn't realized until nearly 70 years later. Article Profile: Fritz Zwicky's Extraordinary Vision Fritz Zwicky was the first to conceive of supernovas, dark matter, and gravitational lenses. So why do so few know his name? Article Profile: Harold C. Urey This Nobel Prize–winning scientist contributed to several fields: chemistry, geochemistry, lunar science, and astrochemistry.