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December 11, 2010

Powerful flares of energy explode from the surfaces of stars. Maelstroms of superhot gas whirl around black holes. The remains of exploded stars hurtle into the cosmos. And "winds" of charged particles from close-together stars ram together like streams from fire hoses.

Yet until just 40 years ago, astronomers were blind to many of these impressive displays. That's because they emit much of their energy in the form of X-rays. Earth's atmosphere absorbs X-rays, though, so the only way to see them is to climb above the atmosphere.

40 years ago tomorrow, the first X-ray satellite did just that. It was launched from a converted drilling platform off the coast of Kenya. To honor the host country, NASA named the craft "Uhuru" -- the Swahili word for "freedom."

By today's standards, the craft's X-ray telescope was crude. It basically allowed astronomers to find an X-ray source in the sky, measure its brightness, and learn a few details about how it worked. But it couldn't map any structure in the objects it saw, and it couldn't even really pin down an object's precise location.

Even so, Uhuru cataloged more than 300 objects, including the first suspected black holes, close-together binary stars, and clusters of galaxies. It also discovered that hot gas fills the space between galaxies in clusters. Most important, it opened astronomers' eyes to a new view of the universe -- a view they've been taking in ever since.


Script by Damond Benningfield, Copyright 2010


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