Sun's Nemesis Pelted Earth with Comets, Study Suggests
A dark object may be lurking near our solar system, occasionally kicking comets in our direction.?
Nicknamed "Nemesis" or "The Death Star," this undetected object could be a red or brown dwarf star, or an even darker presence several times the mass of Jupiter. Why do scientists think something could be hidden beyond the edge of our solar system? Originally, Nemesis was suggested as a way to explain a cycle of mass extinctions on Earth.? The paleontologists David Raup and Jack Sepkoski claim that, over the last 250 million years, life on Earth has faced extinction in a 26-million-year cycle. Astronomers proposed comet impacts as a possible cause for these catastrophes.? Our solar system is surrounded by a vast collection of icy bodies called the Oort Cloud.?If our Sun were part of a binary system in which two gravitationally-bound stars orbit a common center of mass, this interaction could disturb the Oort Cloud on a periodic basis, sending comets whizzing towards us. - See more at: http://www.space.com/8028-sun-nemesis-pelted-earth-comets-study-suggests.html#sthash.hqmP4K3x.dpuf |
Nemesis is a hypothetical red dwarf star or brown dwarf,
originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU (1.5 light-years), somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years. As of 2012, over 1800 brown dwarfs have been identified and none of them are inside the Solar System. There are actually fewer brown dwarfs in our cosmic neighborhood than previously thought. Rather than one star for every brown dwarf, there may be as many as six stars for every brown dwarf. |
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