Monday, 4 October 2010

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Johnald's Fantastical Daily Link Splurge

Close Encounter Coming With Ghostly Green Comet

Posted: 01 Oct 2010 11:19 AM PDT

Comet Hartley 2 will swoop within 11 million miles of Earth on October 20, one of the closest approaches of any comet in the last few centuries.

Hartley 2 is already visible as a pale green streak in the W-shaped constellation Cassiopeia. NASA astronomer Bill Cooke caught the comet on September 28 in a 4-minute exposure taken from a remotely-controlled telescope in Mayhill, New Mexico (Cooke himself was in his home in Huntsville, Alabama, according to NASA's Watch the Skies blog).

Several amateur astronomers have taken gorgeous photos of the comet from their backyards in Italy, Austria, Sweden, Louisiana, New Mexico and Arkansas. As the comet approaches, the ghostly green glow should be visible with small telescopes, binoculars and even the naked eye, if the sky is dark enough. A moonless sky on the night of closest approach should make easy viewing in the northeast, especially just before dawn.

October 20 marks the closest approach of Hartley 2 to Earth since its discovery in 1986. But two weeks later, a spacecraft from Earth will get closer still. The NASA EPOXI mission (formerly known as Deep Impact) will fly within 435 miles of the comet's icy nucleus on November 4 — only the fifth time ever that a spacecraft has been close enough to image a comet's core.

If you catch any great images of the comet, let us know.


Images: 1) EPOXI's view of Hartley 2 on September 5, 60 days before its flyby. NASA/JPL/UM. 2) Bill Cooke, NASA's Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.

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Intelligent Individuals Don't Make Groups Smarter

Posted: 30 Sep 2010 12:27 PM PDT

An early effort at defining general intelligence in groups suggests that individual brainpower contributes little to collective smarts.

Instead, it's social awareness — the ability to pick up on emotional cues in others — that seems to determine how smart a group can be.

"We lack a shared criterion in predicting which groups will perform well and which won't," said psychologist Anita Woolley of Carnegie Mellon University. "There's an underlying factor that seems to drive how individuals perform in multiple domains. I wondered if that was true of groups as well."

In individuals, general intelligence is a measure of each person's tendency to perform similarly on different types of cognitive tests, suggesting an underlying — general — intellectual competence. Exactly what produces those smarts, and how they correlate with biological and environmental factors, is controversial. But even if the causes are unclear, the evidence of individual general intelligence remains.

To determine whether something similar also operated in collective minds, Woolley's team divided 600 test subjects into groups of two to five people, then had each group complete a variety of problem-solving tasks. Afterward the researchers interviewed the groups and each participant. They measured group cohesion and motivation, individual intelligence and personality, and other factors previously associated with group performance.

Their analysis, published Sept. 30 in Science, found several characteristics linked to group performance — and none involved individual intelligence. What mattered instead was the social sensitivity of individual members, the proportion of women (who tend to be more sensitive) in each group, and a balanced participation of conversation.

Gender and social sensitivity are linked, said Woolley, making emotional intelligence and conversation balance the most important factors in group performance. Not only was individual intelligence irrelevant, but group cohesion mattered little. Neither did motivation or happiness — a finding that most workers would find disconcerting.

"Some of our intuitions about how satisfaction and cohesion correlate with performance are a little misguided," Woolley said. "But it's not as if happiness and cohesion are bad.

In future research, Woolley plans to study how group intelligence is affected by size, and how the benefits of increased collaboration can reach a point of diminishing returns. She also wants to know how group intelligence changes when collaboration occurs online.

"The way we're moving now, where everyone is interconnected, it calls into question the whole notion of what intelligence is, whether it's so relevant what an individual can do by themselves" said Woolley. "It's good to move the conversation in that direction."

Image: Michael Cardus/Flickr.

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Citation: "Evidence for a Collective Intelligence Factor in the Performance of Human Groups." By Anita Williams Woolley, Christopher F. Chabris, Alexander Pentland, Nada Hashmi, Thomas W. Malone. Science, Vol. 329 No. 6000, October 1, 2010.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on an ecological tipping point project.

Solar System's Shield Could Leak Cosmic Rays

Posted: 30 Sep 2010 12:09 PM PDT

The bubble that separates our sun from the galaxy is surprisingly active. The second global map from the Interstellar Boundary Explorer, or IBEX, shows that the edge of the solar system changes more quickly and drastically than scientists expected.

"If we've learned anything from IBEX so far, it's that the models we were using for interaction of the solar wind with the galaxy were just dead wrong," said IBEX principal investigator David McComas of the Southwest Research Institute in a press briefing Sept. 30.

The new data could have implications for future astronauts on long interplanetary voyages, and could make scientists rethink which extrasolar planets could support life.

IBEX images the boundary of the solar system by capturing high-speed neutral atoms bouncing off the bubble that stands between our star and all the others. This bubble, called the heliosphere, is inflated by the solar wind, and acts as a protective shield from a downpour of charged particles that would otherwise bombard planets and damage life.

Last year, IBEX's first map shocked scientists by showing an unexpected tight ribbon of neutral particles circling the solar system. Astronomers are still unsure what caused the ribbon, although they believe it is related to the galactic magnetic field that hugs the solar bubble like a wire mesh cage.

Now, the second map brings further surprises. In just six months, a bright "knot" at the tip of the ribbon appears to have relaxed, or "untied." This means the force field that guards the solar system from radiation changes on a much shorter timescale than anyone had anticipated.

"We didn't understand where the ribbon came from in the first place," McComas said. "It's even more confounding now, to know the structure can change on such very short timescales." The results are in the Journal of Geophysical Research.

Compared to the forces acting on the heliosphere, McComas said, six months is an eye blink. The inside of the bubble, which is shaped by the sun, should change only with the 11-year solar cycle. The forces acting on the outside change on timescales of tens of thousands of years.

The culprit could be a weakening solar wind. Measurements from two other solar observers, ACE and Ulysses, show that the force exerted by the solar wind — and therefore the size of the bubble — has dropped off by a factor of two over the past 18 years.

"The overall inflation, the blowing up of this bubble, has reduced by a factor of two, and the heliosphere surely has shrunk over this time," McComas said. "Maybe this is part of what's going on with the changes we're seeing."

A smaller bubble makes a worse shield, McComas added. As the heliosphere shrinks, more galactic cosmic rays can make their way into the inner solar system (see video above).

That could prove critical for astronauts spending months in transit to other parts of the solar system, like Mars or a nearby asteroid, he said.

"The fact that this radiation can change on the timescales on which we plan and execute manned missions to other places in the solar system is very important," he said. "We have to get that right before we use this to rely on this for things as critical as planning manned missions."

IBEX's results could also provide insight into what would make an extrasolar planet a good place for life, said stellar physicist Merav Opher of George Mason University.

"By understanding how astrospheres protect other solar system environments, we will be able to predict in a better way the habitable zones for extrasolar planets," she said. "For us it's not just looking for the right temperature for water. If this planet has been bombarded by a huge dose of radiation, life cannot live there. It's a key component that needs to be folded in when you are describing habitable zones."

Video: Goddard Conceptual Image Lab/Walt Feimer

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