Hubble maps cosmic web of 'clumpy' dark matter in 3-D

SEATTLE - An international team of astronomers using NASA's Hubble Space Telescope has created the first three-dimensional map of the large-scale distribution of dark matter in the universe.

Dark matter is an invisible form of matter whose total mass in the universe is more than five times that of "normal" matter (i.e., atoms). The nature of dark matter is still unknown. Its presence in the universe is inferred from its current influence within galaxies and clusters of galaxies, and the gravitational effect it has had on the evolution of structure in the universe. The first direct detection of dark matter was made this past year through observations of the Bullet Cluster of galaxies.

This new map provides the best evidence to date that normal matter, largely in the form of galaxies, accumulates along the densest concentrations of dark matter. The map reveals a loose network of filaments that grew over time and intersect in massive structures at the locations of clusters of galaxies.

The map stretches halfway back to the beginning of the universe and shows how dark matter has grown increasingly "clumpy" as it collapses under gravity.

The dark matter map was constructed by measuring the shapes of half a million faraway galaxies. To reach Hubble, the light of the galaxies traveled through intervening dark matter. The dark matter deflected the light slightly as it traveled through space. Researchers used the observed, subtle distortion of the galaxies' shapes to reconstruct the distribution of intervening mass along Hubble's line of sight, a method called "weak gravitational lensing."

For astronomers, the challenge of mapping dark matter in the universe has been similar to mapping a city from nighttime aerial snapshots showing only streetlights. Dark matter is invisible, so only the luminous galaxies can be seen directly. These new map images are equivalent to seeing a city, its suburbs and country roads in daylight for the first time. Major arteries and intersections become evident, and a variety of neighborhoods are visible.

Mapping dark matter's distribution in space and time is fundamental to understanding how galaxies grew and clustered over billions of years. Tracing the growth of clustering in dark matter may eventually also shed light on dark energy, a repulsive form of gravity that would have influenced how dark matter clumps.

The research results appeared online today in the journal Nature and were presented at the 209th meeting of the American Astronomical Society in Seattle, Wash., by Richard Massey and Nick Scoville. Both researchers are from the California Institute of Technology, Pasadena, Calif.

"It's reassuring how well our map confirms the standard theories for structure formation," said Massey. He calls dark matter the "scaffolding" inside of which stars and galaxies have been assembled over billions of years.

Researchers created the map using the Hubble's largest survey to date of the universe, the Cosmic Evolution Survey, otherwise known as COSMOS. The survey covers an area of sky nine times the area of the Earth's moon. This allows for the large-scale filamentary structure of dark matter to be evident. To add 3-D distance information, the Hubble observations were combined with multicolor data from powerful ground-based telescopes, Europe's Very Large Telescope in Chile, Japan's Subaru telescope in Hawaii, the U.S.'s Very Large Array radio telescope, New Mexico, as well as the European Space Agency's orbiting XMM-Newton X-ray telescope.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute, Baltimore, conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.

source: spaceflightnow.com

Pluto's revenge: 'Word of the Year' award

(CNN) -- Pluto may no longer be a planet, but it has a new claim to fame: "Plutoed" has been chosen 2006 Word of the Year by the American Dialect Society.

The society defined "to pluto" as "to demote or devalue someone or something, as happened to the former planet Pluto when the General Assembly of the International Astronomical Union decided Pluto no longer met its definition of a planet."

The former planet had some tough competition in the voting, which took place Friday at the ADS' annual meeting, held in Anaheim, California.

"Plutoed" won in a runoff against "climate canary," defined as "an organism or species whose poor health or declining numbers hint at a larger environmental catastrophe on the horizon."

The runner-up was "macaca" or "macaca moment," defined as "treating an American citizen as an alien" -- a reference to a campaign remark by former Virginia Sen. George Allen that some say marked the beginning of the end for his re-election hopes.

Also in the running for Word of the Year were YouTube; surge (referring to a large, but brief, increase in troop strength); and flog ("a fake blog created by a corporation to promote a product or a television show").

Like any good awards show, the ADS meeting had multiple categories.

In the "Most Unnecessary" category, "SuriKat" (the supposed nickname of the baby girl of Tom Cruise and Katie Holmes) beat out "the decider," President Bush's description in April of his position in relation to whether Donald Rumsfeld kept his job as secretary of defense.

The "Most Outrageous" award went to "Cambodian accessory," defined as "Angelina Jolie's adopted child who is Cambodian."

In the "Most Euphemistic" category, the winner was "waterboarding," defined as "an interrogation technique in which the subject is immobilized and doused with water to simulate drowning."

The ADS has been choosing Words of the Year since 1990. The Word of the Year for 2005 was "truthiness," invented by Comedy Central's "The Colbert Report," and defined by the ADS as "what one wishes to be the truth regardless of the facts." (Read the full list of winners for 2006 and past years)

Winning words or phrases don't have to be brand new; what's important is that they gained new prominence in the past year.

The society is dedicated to the study of the English language in North America, and includes academics, writers, and others.

source: cnn.com

Google joins LSST project

NEW YORK: Google has become part of a group of universities, national laboratories and private foundations, which is building the Large Synoptic Survey Telescope to probe into the mysteries of the universe.

The telescope, to become operational in 2013, has a three billion pixel digital camera, which is capable of surveying the whole of visible sky in multiple colors every week. It is particularly scheduled to look into the mysteries of dark matter and dark energy and will provide a colorful glimpse on celestial objects that change or move rapidly like the exploding supernovae, near-earth asteroids and the Kuiper Belt objects.

The decade-long survey is expected to generate more than 30,000 gigabytes of image data every night and Google's participation in the project is to ensure that this massive data is properly and organized and preserved for proper and easy use.

Donald Sweeney, project manager for the Large Synoptic Survey Telescope said Google will help organize "the seemingly overwhelming volumes of collected data" into a database, which will make discoveries available in real time for scientists and non-scientists alike.

William Coughran, Google's vice president of engineering said the company's mission is to take the world's information and make it universally accessible and useful. He said the data from the project will be an important part of the world's information, and by being involved in the project Google hopes to make it easier for that data to become accessible and useful.

full story: earthtimes.org

Biologist at Field discovers rare bat

More than a century after biologists discovered the only known sucker-footed bat species, a Field Museum biologist working in Madagascar has found a second variety that relies on the same strange means of locomotion, using flat suction pads to climb up smooth leaves.

The new bat, which museum biologist Steven Goodman found by the thousands, was hiding in plain view amid the farms and grazing lands of the vast island.

The 19th and 20th Century biologists who described the first species of sucker-footed bats called them "exceedingly rare and remarkable." While the new bat species is not especially rare, its strategy for clinging to leaves is virtually unknown among mammals.

Among bats, the only other varieties that use suckers are the "disk-winged" bats of Central and South America, which have pads in a different place.

"If we already had described 100 other species like this and found one more, it would be less interesting," said Link Olson, curator of mammals at the University of Alaska Museum in Fairbanks.

Goodman's paper on the new bat appears in the current issue of the journal Mammalian Biology.

Before the new discovery, the other sucker-footed bat in Madagascar was the sole member of its biological "family"--a technical distinction, but one that experts say is extremely unusual among mammals.

"Most families have dozens or thousands of species," said Larry Heaney, curator of mammals at the Field Museum. "To be placed as the only species in a family means there are no known species that shared an ancestor with that animal in a long time."

Goodman and a team of researchers from Madagascar found the new bat through painstaking biological surveys. Goodman was in Madagascar and could not be reached for comment Friday, but his colleagues said such surveys typically consist of first-hand observations as well as catching bats with nets hung along their flying routes.

source: chicagotribune.com

Scientists' Report Documents ExxonMobil’s Tobacco-like Disinformation Campaign on Global Warming Science

Oil Company Spent Nearly $16 Million to Fund Skeptic Groups, Create Confusion

WASHINGTON, DC, Jan. 3–A new report from the Union of Concerned Scientists offers the most comprehensive documentation to date of how ExxonMobil has adopted the tobacco industry's disinformation tactics, as well as some of the same organizations and personnel, to cloud the scientific understanding of climate change and delay action on the issue. According to the report, ExxonMobil has funneled nearly $16 million between 1998 and 2005 to a network of 43 advocacy organizations that seek to confuse the public on global warming science.

"ExxonMobil has manufactured uncertainty about the human causes of global warming just as tobacco companies denied their product caused lung cancer," said Alden Meyer, the Union of Concerned Scientists' Director of Strategy & Policy. "A modest but effective investment has allowed the oil giant to fuel doubt about global warming to delay government action just as Big Tobacco did for over 40 years."

source: ucsusa.org

Search on for Russian rocket parts in Wyoming

PETERSON AIR FORCE BASE, Colorado (AP) -- A spent Russian booster rocket re-entered the atmosphere Thursday over Colorado and Wyoming, the North American Aerospace Defense Command said.

NORAD spokesman Sean Kelly said the agency was trying to confirm a report that a piece of the rocket may have hit the ground near Riverton, Wyoming, at about 6 a.m.

Kelly said military personnel had not yet reached the scene.

No damage was reported and the debris was not believed to be hazardous, NORAD said.

Eyewitnesses reported seeing flaming objects in the sky at the time the rocket was re-entering, Kelly said.

"It was pretty spectacular," said Riverton Police Capt. Mark Stone, who said he saw the burning object while he was retrieving his newspaper. "My first concern is that we had some sort of aircraft that was coming down. It was definitely leaving a burning debris trail behind it."

He said he could tell it was a fairly large object, but it was too high to determine what it was.

A trooper found a 3-by-5 foot area burned in the snow about 35 feet from the edge of the highway, but found no object, Sgt. Stephen Townsend of the Wyoming Highway Patrol said. The highway was closed at the time because of wintry weather, he said.

NORAD identified the rocket as an SL-4 that had been used to launch a French space telescope in December, and Kelly said U.S. spacewatchers knew the rocket was coming down.

"Objects falling from space are almost an everyday occurrence," he said.

source: cnn.com

North Korea's Biochemical Threat

Fifty miles south of the Chinese border lies the rural town of Chongju. Like many North Korean towns, it is a small, impoverished place where people scratch a bare existence from government-controlled farms. What photographs exist of Chongju reveal a brown landscape of depleted-looking fields and shanty-style houses. It is hard to believe anything of value grows here.

But, according to intelligence reports, something precious to the North Korean regime may be under cultivation in Chongju. Beyond the shacks stands an installation suspected of being a component in North Korea's bioweapons (BW) research and development program. The effort is steeped in a level of secrecy possible only in a totalitarian state, but it is thought to encompass at least 20 facilities throughout the country. Another 12 plants churn out chemical weapons.

In late November, delegates of the signatory countries to the Biological and Toxin Weapons Convention (BTWC) met at the United Nations office in Geneva for the sixth review of the treaty since its inception in 1972. The meeting took place just weeks after North Korea publicly added the third prong to its capacity for weapons of mass destruction (WMD) by testing a nuclear device.

continue reading: popularmechanics.com

Five Hackers Who Left a Mark on 2006

In the security year that was 2006, zero-day attacks and exploits dominated the headlines.

However, the year will be best remembered for the work of members of the hacking—er, security research—community who discovered and disclosed serious vulnerabilities in the technologies we take for granted, forced software vendors to react faster to flaw warnings and pushed the vulnerability research boat into new, uncharted waters.

In no particular order, here's my list of five hackers who left a significant mark on 2006 and set the stage for more important discoveries in 2007:

H.D. Moore

H.D. Moore has always been a household name—and a bit of a rock star—in hacker circles. As a vulnerability researcher and exploit writer, he built the Metasploit Framework into a must-use penetration testing tool. In 2006, Moore reloaded the open-source attack tool with new tricks to automate exploitation through scripting, simplify the process of writing an exploit, and increase the re-use of code between exploits.

Moore's public research also included the MoBB (Month of Browser Bugs) project that exposed security flaws in the world's most widely used Web browsers; a malware search engine that used Google search queries to find live malware samples; the MoKB (Month of Kernel Bugs) initiative that uncovered serious kernel-level flaws; and the discovery of Wi-Fi driver bugs that could cause code execution attacks.

Love him or hate him—hackers marvel at his skills while software vendors decry his stance on vulnerability disclosure—Moore's work nudged the security discussion to the mainstream media and confirmed that vulnerability research will remain alive in 2007.

Jon "Johnny Cache" Ellch and David Maynor

At the Black Hat Briefings in Las Vegas, Jon "Johnny Cache" Ellch teamed up with former SecureWorks researcher David Maynor to warn of exploitable flaws in wireless device drivers. The presentation triggered an outburst from the Mac faithful and an ugly disclosure spat that still hasn't been fully resolved.

For Ellch and Maynor, the controversy offered a double-edged sword. In many ways, they were hung out to dry by Apple and SecureWorks, two companies that could not manage the disclosure process in a professional manner. In some corners of the blogosphere, they were unfairly maligned for mentioning that the Mac was vulnerable.

However, among security researchers who understood the technical nature—and severity—of their findings, Ellch and Maynor were widely celebrated for their work, which was the trigger for the MoKB (Month of Kernel Bugs) project that launched with exploits for Wi-Fi driver vulnerabilities.

Since the Black Hat talk, a slew of vendors—including Broadcom, D-Link, Toshiba and Apple—have shipped fixes for the same class of bugs identified by Ellch and Maynor, confirming the validity of their findings.

Maynor has since moved on, leaving SecureWorks to launch Errata Security, a product testing and security consulting startup.

Mark Russinovich

Before Mark Russinovich's mind-blowing expose of Sony BMG's use of stealth technology in a DRM (digital rights management) scheme, "rootkit" was a techie word. Now, the word is being used in marketing material for every anti-virus vendor, cementing Russinovich's status as a Windows internals guru with few equals.

The Sony rootkit discovery highlighted the fact that anti-virus vendors were largely clueless about the threat from stealth malware and forced security vendors to build anti-rootkit scanners into existing products.

Russinovich, who now works at Microsoft after Redmond acquired Sysinternals, spent most of 2006 expanding on his earlier rootkit warnings and building new malware hunting tools and utilities.

Joanna Rutkowska

Polish researcher Joanna Rutkowska also used the spotlight of the 2006 Black Hat Briefings to showcase new research into rootkits and stealthy malware. In a standing-room-only presentation, she dismantled the new driver-signing mechanism in Windows Vista to plant a rootkit on the operating system and also introduced the world to "Blue Pill," a virtual machine rootkit that remains "100 percent undetectable," even on Windows Vista x64 systems.

In 2006, Rutkowska also pinpointed inherent weaknesses in anti-virus software; warned that the major operating system vendors are not yet ready for hardware virtualization technology and confirmed fears that stealth malware is the operating system's biggest security threat.

source: eweek.com

The stuff of dreams

1. Dilatants - fluids that get more solid when stressed. The classic example is a mixture of cornflour and water - it's runny until you hit it when it becomes solid.

This video shows how that it possible to run across an apparently liquid pool of the stuff because your footfalls solidify it. If you stop, you sink.

I like this video better though - it shows how sound waves from a subwoofer produce interesting shapes in a dilatant. If you want to have a go yourself, try this recipe.

2. Auxetic materials - materials that get thicker when stretched. Pull them in one direction and they expand in another.

This video (.mov format) from Bolton University, UK, shows an auxetic foam in action. I like these because they are totally counter-intuitive - you just expect things to get thinner when stretched. Read more about them in a feature here or on this research page.

3. Superfluids - liquids that flow without friction. They can effortlessly flow through the tiniest of cracks and will even flow up the walls of a beaker and out the top. It's possible because all the atoms in a superfluid are in the same quantum state, so they all have the same momentum and move together. To make a superfluid you must cool helium down to a couple of a degrees above absolute zero - not one to try at home. They can be used to make super-sensitive gyroscopes to test theories about gravity.

Sadly I couldn't find any spectacular videos of supefluids in action. Here's a not-too-exciting one of superfluid helium drops (mpg format). Read more here.

4. Ferrofluids - magnetic fluids that can look spectacular. They're made from nanoscale magnetic particles suspended in a liquid. The spectacular sculpture in the video below is made using a ferrofluid and electromagnets.

Ferrofluids can be used to drive speakers or make shock absorbers that vary their stiffness in milliseconds. This guide shows you how to make your own ferrofluid at home.

5. Dry ice. Carbon dioxide freezes at -78.5 °C and it's fun and versatile stuff. These videos show how it can produce massive amounts of bubbles when mixed with soap and water, drive a simple cannon , transform your swimming pool, produce pretty patterns when dropped onto water in small chunks and spice up the all-too-familiar Diet Coke and Mentoes reaction. You can even freeze soap bubbles hard and pick them up, if you follow this guide. A block of dry ice will also distract mosquitos - they fly towards carbon dioxide because it's usually in the breath of their prey. Last of all, perhaps the best thing is that it's not that hard to get hold of - search online and you'll see.

source: newscientist.com

Liquid Lakes on Titan

The existence of oceans or lakes of liquid methane on Saturn's moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it has not been possible to confirm their presence. Until the Cassini flyby of July 22, 2006, that is.

Radar imaging data from the flyby, published this week in the journal Nature, provide convincing evidence for large bodies of liquid. This image, used on the journal's cover, gives a taste of what Cassini saw. Intensity in this colorized image is proportional to how much radar brightness is returned, or more specifically, the logarithm of the radar backscatter cross-section. The colors are not a representation of what the human eye would see.

source: saturn.jpl.nasa.gov

The Mathematics Of Cloaking

The theorists who first created the mathematics that describe the behavior of the recently announced "invisibility cloak" have revealed a new analysis that may extend the current cloak's powers, enabling it to hide even actively radiating objects like a flashlight or cell phone.

Allan Greenleaf, professor of mathematics at the University of Rochester, working with colleagues around the globe, has announced a mathematical theory that predicts some strange goings on inside the cloak-and that what happens inside is crucial to the cloak's effectiveness.

In October, David R. Smith, associate professor of electrical and computer engineering at Duke University, led a team that used a circular cloaking device to successfully bend microwaves around a copper disk as if the disk were invisible. In 2003, however, Greenleaf and his colleagues had already developed the mathematics of invisibility.

full story: spacemart.com

Space telescope to seek out Earth-like planets

A French-led satellite project took off Wednesday on a mission to seek new Earth-like planets outside the solar system.

The multinational mission will also study stars on a quest to uncover more about their interior, the European Space Agency (ESA) announced.

The Corot project sends into orbit a telescope that is able to detect smaller planets than are currently known.

With the spacecraft, astronomers expect they will discover between 10 and 40 rocky objects slightly larger than Earth, as well as tens of new gas giants similar to Jupiter.

Should the mission uncover such planets, they will constitute a new class of planets altogether.

"Corot will be able to find extra-solar planets of all sizes and natures, contrary to what we can do from the ground at the moment," Claude Catala, one of the researchers associated with the project, told France Info radio.

"We expect to obtain a better vision of planet systems beyond the solar system, about the distribution of planet sizes," Catala said.

"And finally, it will allow us to estimate the likelihood of there existing planets resembling the Earth in the neighbourhood of the sun or further away in the galaxy."

The telescope lifted off into a polar orbit from the Baikonur Cosmodrome on Wednesday morning ET.

source: ctv.ca

Why practice can't make perfect

Study shows our brains were meant to handle variable, not repetitive, tasks

Ever wonder why your tee shot still slices after smacking 30 buckets of balls on the driving range?

Or why an NBA superstar can still miss a free throw after practising the shot thousands of times?

Well, according to a new study out of Stanford University, a quirk of the human brain ensures that practice can never make perfect.

Human brains have evolved to consider anew even the most practised of motions before launching into them, the study says. And that planning process, often momentary and subconscious, can change the outcome of every move you make.

Our brains ensure that we are "doomed" to make mistakes, says Stanford scientist Krishna Shenoy, whose paper appears this week in the journal Neuron.

Scientists have long believed that the fault for such things as missed shots and errant fastballs lay in the muscles, says Shenoy, an assistant professor in the school's department of electrical engineering and neurosciences program. "The fundamental tenet of the field is ... that you can't activate your muscles the same way every time," he says. "Another fundamental assumption is that your brain can plan that same movement each and every time."

Shenoy's groundbreaking study, however, places at least half the blame on the brain, arguing that its obsessive planning function provides a fertile source for errors.

The failed free throw, for example, is likely foretold seconds before the player's arm is set in motion, as the brain's plan – almost certainly subconscious – has ruined the shot.

"You are doomed to have variability in your movement," says Shenoy. "And it's not just because your muscles can't work perfectly, but also because your brain is incapable, it appears, of planning the same movement each and every time."

source: thestar.com

STEREO Sends Back First Solar Images

NASA's twin Solar Terrestrial Relations Observatories (STEREO) sent back their first images of the sun this week and with them a view into the sun's mounting activity.

One image shows the first coronal mass ejection (CME) observed by STEREO's Ahead spacecraft, taken Dec. 9.

"We're absolutely thrilled. We've been looking forward to STEREO's unique vantage point for over 10 years now and the community couldn't be happier with these first views," said Michael Kaiser, STEREO project scientist at NASA Goddard Space Flight Center, Greenbelt, Md.

"Now we're holding our breath to see what the next big CME looks like in 3-D, so we can really start to answer some interesting questions."

After a successful launch on Oct. 25 from Cape Canaveral Air Force Station, Fla., STEREO spent the first few minutes separating from its stacked configuration aboard the single Delta II rocket. Shortly afterwards, mission operations personnel at The Johns Hopkins University Applied Physics Laboratory, (APL) Laurel, Md., monitored the two observatories as they traveled in an elliptical orbit from a point close to Earth to one extending just beyond the moon.

source: nasa.gov

Are you an Aries? Then you may suck at driving

Next time you smash your ride into something, just blame it on the stars. Tell the cop Mercury was in retrograde, causing your driving to follow suit and thus leading to the crash of your Mercury. Watch out if you're an Aries with an Aries - that's a dangerous thing to be.

InsuranceHotline.com, a Canadian website that provides insurance quotes to drivers, conducted a study correlating accident rates to zodiac signs. You'd think age and ability would hold more water, but apparently astrology trumps even changing zip codes when determining how prone a particular driver is to accidents. Libras are the worst, followed by Aquarians. The best were Leos and Geminis. As for that Aries, they have a "me first" attitude that leads them into bad juju. If InsuranceHotline's study is accurate, it appears that everyone on the road is an Aries.

[Source: Reuters via scotsman.com]

NASA Telescope Picks Up Glow of Universe's First Objects

New observations from NASA's Spitzer Space Telescope strongly suggest that infrared light detected in a prior study originated from clumps of the very first objects of the Universe. The recent data indicate this patchy light is splattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away.

"We are pushing our telescopes to the limit and are tantalizingly close to getting a clear picture of the very first collections of objects," said Dr. Alexander Kashlinsky of NASA's Goddard Space Flight Center, Greenbelt, Md., lead author on two reports to appear in the Astrophysical Journal Letters. "Whatever these objects are, they are intrinsically incredibly bright and very different from anything in existence today."

Astronomers believe the objects are either the first stars -- humongous stars more than 1,000 times the mass of our sun -- or voracious black holes that are consuming gas and spilling out tons of energy. If the objects are stars, then the observed clusters might be the first mini-galaxies containing a mass of less than about one million suns. The Milky Way galaxy holds the equivalent of approximately 100 billion suns and was probably created when mini-galaxies like these merged.

source: spitzer.caltech.edu

Giant New Telescope Will Probe The Universe

The future of European astronomy is poised to enter a new era of discovery with the decision announced today by ESO's governing body to proceed with detailed studies for the European Extremely Large Telescope (E-ELT). This three year study, with a budget of 57 million euro, will prepare the way for construction of the world's largest optical/infrared telescope that will revolutionise ground-based astronomy. Astronomers from the UK have played crucial roles in reaching this decision.

The E-ELT will be more than hundred times more sensitive than the present-day largest optical telescopes, such as the 10-m Keck telescopes or the 8.2-m VLT telescopes and will answer some of the biggest questions about the Universe in which we live.

full story: spacedaily.com

Astronauts rewire half of space station

By Mike Schneider, Associated Press | December 15, 2006

Two spacewalking astronauts successfully rewired half of the international space station yesterday, a job that when finished will allow the orbiting outpost to double the size of its crew and add two more labs in the coming years.

NASA immediately started powering up systems aboard a large section of the space station; the power had to be turned off for the spacewalkers' safety while they were handling the electrical connections.

The space agency also rushed to get the space station's ammonia cooling system operating again before the new electrical equipment overheated. It took less than an hour for the cooling system to start running smoothly.

The rewiring job involved switching the space station from its old, temporary power source to its brand-new one -- a pair of solar arrays that were delivered in September. The spacewalkers had to unhook three dozen electrical hoses and reconnect them.

During a short break, the spacewalkers watched shooting stars and the blaze of the Northern Lights, caused by solar flares colliding with Earth's atmosphere. "Gosh, they're beautiful," Curbeam said.

The National Aeronautics and Space Administration was considering a fourth spacewalk in which astronauts could manually fold up the old solar array, which failed to retract fully by remote control Wednesday. The accordion-like 115-foot array, which had provided temporary power to the space station, retracted about halfway -- enough to allow the new pair of solar arrays to rotate.

The half-retracted array presents no danger, NASA said. In a worst-case scenario, it could be jettisoned.

"It's a little disappointing with the solar array, but folks . . . understand you're going to have a little hiccup," said Joel Montalbano, a space station flight director. "NASA probably does its best with their back against the wall."

Look into the eyes of our Sun

“NewScientist reports that Japan’s Hinode (Solar-B) spacecraft has captured videos of surface details of the Sun, including the development of loops of hot plasma above the surface, and activity around sunspots. From the article: ‘It is hoped that its observations will shed light on what triggers solar eruptions — called coronal mass ejections (CMEs). These ejections spew out radiation that poses a health risk for astronauts, and they can also knock out satellites.”

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China’s white dolphin called extinct after 20 million years

“The white dolphin known as baiji, shy and nearly blind, dates back some 20 million years. Its disappearance is believed to be the first time in a half-century, since hunting killed off the Caribbean monk seal, that a large aquatic mammal has been driven to extinction.”

full story: cnn.com