Word: supernova
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...next supernova to be seen by the naked eye happened only 32 years later, in 1604, in the constellation Ophiuchus, and its best-remembered witness was Brahe's former assistant Johannes Kepler. Unlike most supernovas, this one was seen before it reached maximum brightness, so Kepler's descriptions of the blazing star are of particular interest to astronomers. His observations would have been even more detailed and valuable had they been made with a telescope. Unfortunately, the star's timing was off. The supernova lighted the night skies just a scant five years before Galileo made the first documented telescopic...
...previous 1,800 years of astronomical history are any guide, astronomers say, a supernova visible to the naked eye should occur in or near the Milky Way galaxy four times every thousand years or so. But from 1604 to 1987, none were recorded. (The supernova of 1885, just on the threshold of visibility in the night sky, took place in the Andromeda galaxy, 2.2 million light-years away.) To be sure, many stars flared up during this interval. But astronomers now know they were not supernovas but nearby novas. These are shorter-lived events, caused by the sudden explosion...
...until the 1930s that Caltech Astronomer Fritz Zwicky recognized supernovas (he coined the name) as a class of exploding star fundamentally different from ordinary novas. With Colleague Walter Baade, he began formulating the modern theory about how supernovas explode and launched the first systematic search for them. While the average galaxy has only an occasional supernova, Zwicky reasoned, there are so many distant galaxies visible through large telescopes, astronomers should have no trouble finding the great explosions popping out all over the universe. At first Zwicky's colleagues thought the idea ridiculous, but over the four decades that followed...
There is another possible scenario: if a star is a minimum of 30 to 40 times as massive as the sun, its gravitational collapse could be so violent that it may never become a supernova at all. Instead of bouncing back at the instant of maximum scrunch, the core continues its collapse indefinitely, forming a bizarre object of infinitesimal size and nearly infinite density, with a gravitational field so intense that light itself cannot escape -- a black hole. In effect, the entire, tremendous mass of the star has gone down a cosmic drain...
...rapid drop in ultraviolet light, scientists began to wonder. Says Robert Kirshner, of the Harvard-Smithsonian Center for Astrophysics: "The spectrum we're seeing in the ultraviolet resembles the spectrum of a Type I. That's a puzzle." Admits Texas' Wheeler: "There are some funny features in this supernova...