Word: pulsars
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...galaxy. When one occurs, it gives off more light than all of the billions of other stars in the galaxy combined. It is thought to leave behind a glowing, expanding cloud of gases at the center of which is a small, rapidly spinning, incredibly dense neutron star (or pulsar) that gives off regularly spaced radio signals. Only four supernovas have been recorded in the Milky Way galaxy since the year 1000. The best-known one was witnessed by Chinese astronomers in 1054 and has since expanded into the famed Crab nebula; the last two took place within 32 years...
...only known evidence of earlier supernovas in the Milky Way are the pulsars they left behind. One of the closest to be detected is in the Gum nebula, which is in the constellation Vela and only 1,500 light years away. Thus, when the star that formed Gum exploded-some 10,000 to 20,000 years ago (an estimate derived from the current signal rate of the pulsar)-it probably flared up briefly in the sky as bright as a quarter-moon. It also may have showered the earth with enough dangerous radiation to have produced significant mutations in terrestrial...
...constellations Vela and Carina-flanked by two larger circles. Michanowsky identified one of these larger circles as a representation of the bright star Canopus. The other circle, which was even bigger, had no existing counterpart in the sky. But it was approximately at the site of the invisible pulsar. Could the second circle be a primitive drawing of the supernova...
...prohibitive. Late last year Bulova brought out an improved and cheaper version, the $395 Accuquartz, believed by many to be the best quartz watch on the market. By then Timex had begun marketing a quartz-crystal watch for $125. Hamilton came out with its $2,100 quartz-crystal Pulsar, and last month Japan's Seiko brought its three quartz timepieces to the U.S., the cheapest selling for $450. This week Benrus will introduce the first quartz watch for women. Among the Swiss companies, Omega, Piaget, Girard Perregaux and Longines are selling quartz watches at prices from...
...Nebula supernova occurred much earlier-about 9000 B.C., according to estimates based on the current signal rate of Gum's pulsar. The sudden and brief appearance at that time of what seemed to be a new and brightly glowing star-probably as luminous as a quarter moon and visible even during full daylight-may have sufficiently moved a primitive sky-gazer to scrawl or carve his impressions on a cave wall. And if an archaeologist should ever find such a drawing, its age could be determined by using radioactive "clocks" and other dating methods on other objects...