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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: Most Comets May Be Solar System Aliens
10 June 2010 3:15 pm
Comet McNaught, shown here in a 2007 Earth flyby, may need a passport when it returns later this month. New research suggests that it and trillions of its cousins were actually born light-years away. Computer simulations reported online today in Science reveal that the Oort cloud—a swarm of comets, including McNaught, that orbit the sun far beyond Pluto—contains too many comets for them to have been generated locally. In fact, the simulation suggests, over 90% of the comets in the Oort cloud probably originated around other stars. Billions of years ago, the researchers explain, our solar system congealed along with many others in relatively close proximity inside a nebula—a vast cloud of dust and gas that acts as sort of a galactic hatchery. As the sun condensed and migrated out of the nebula, it carried the rest of our solar system with it. But its gravity also snagged a huge number of comets from the Oort clouds surrounding its siblings in the process. So welcome back, McNaught, regardless of where you came from.
See more ScienceShots.