Word: nebula
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...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 of each other around the turn of the 17th century...
...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...
...great event-markings that could be archaeologically dated to determine more precisely when the Vela supernova occurred-NASA Astronomers John C. Brandt, Stephen P. Maran and Theodore Stecher last year issued an appeal. They asked archaeologists to be on the lookout, especially in the Southern hemisphere-where the Gum nebula can be best observed-for any unidentified ancient symbols that might have been painted or carved to represent the supernova...
Returning to the site of the markings in Bolivia, Michanowsky noted that the region of the sky in which the Gum nebula lies does not look remarkable to the naked eye. Nonetheless, it has long been called Lakha Manta (The Gateway to Hell) by the Indians, for reasons they are unable to explain. More tantalizing still, Michanowsky found that among some lowland tribes this humdrum part of the sky is known as the Region of the Chase of the Celestial Ostrich, a bird revered in Indian mythology. According to Indian lore, the ostrich was driven across...
...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...