Word: nebula
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Dates: during 1970-1979
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...that of Dutch Astronomer Jan Oort, who says that comets exist by the billions in a vast swarm of debris beyond Pluto that stretches halfway to the nearest star, Proxima Centauri. The debris, called Oort's Cloud, coalesced from the swirling dust and gases in the original solar nebula, from which the sun, earth and other planets and moons were formed. Thus comets are primordial matter, largely unchanged since the solar system's birth. (Lyttleton ascribes a different origin to the comets: he thinks that they are swept up by solar gravity as the sun wheels around...
...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...