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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Two New Moons Around Uranus
31 October 1997 8:00 pm
There's no moon in the sky tonight for Halloween, but creatures of the night with powerful telescopes have two new targets: A team of astronomers announced today that it has spotted two new moons around Uranus, bringing the count to 17. One of the discoverers, Philip Nicholson of Cornell University, says the satellites probably escaped detection for so long because they are so small--approximately 80 and 160 kilometers in diameter--and their eccentric orbits are far from the planet.
Nicholson and his colleagues, including Joseph Burns of Cornell, Brett Gladman of the University of Toronto, and J. J. Kavelaars of McMaster University in Hamilton, Ontario, first spotted the objects during a search for satellites of the gas giant. No one had made a systematic search for uranian moons with modern equipment, says Nicholson, and although the Voyager spacecraft had discovered 10 moons on its 1986 flyby, its view was much narrower than that of ground-based telescopes. As a side project to other observations, the team used the Hale telescope on Mount Palomar, California, to look for slow-moving objects near Uranus that might be moons.
In September, the astronomers took three exposures of the sky around Uranus, 30 minutes apart, for two nights in a row. When they analyzed their data a few weeks later, they found two objects moving slowly enough to be moons. This week, they were able to follow up their observations to confirm that the objects were not simply ill-placed comets or asteroids orbiting the sun. Observers in New Mexico and Hawaii also confirmed the sightings, and the International Astronomical Union announced the find in its Internet circular today.
The moons' eccentric orbits suggest that they may have once orbited the sun, but were captured by Uranus's gravity, says astronomer David Jewitt of the University of Hawaii. The other gas giants, Jupiter, Saturn, and Neptune, all have eccentric moons, and the new uranian satellites suggest that Uranus--even though its equator is tipped sideways--may have evolved like other gas giants. The leading theory to explain such moons holds that the planets once had much larger atmospheres, which were able to slow down and capture smaller objects as they traveled around the sun. "There is nothing funny about Uranus in this regard," Jewitt says. "It appears they are all good at capturing things."