Though solar eclipses can happen two to five times a year, total solar eclipses with the Sun fully covered by the Moon are rare. The total solar eclipse of 22nd July 2009 was a once-in-a-century event because it lasted so long – 6 minutes and 39 seconds; an event not to be surpassed until at least June 2132. If you missed it, here are some incredible pictures from this rare occurrence.

A solar eclipse almost literally takes place when the stars align, that is to say when the Moon passes between the Earth and the Sun, covering the Sun fully or partially. In addition, it occurs only during a new moon when the Sun and the Moon are in conjunction, meaning they appear closer from Earth than they really are.

Read More Via Environmental Graffiti

Uranium exists on the moon, according to new data from a Japanese spacecraft.

The findings are the first conclusive evidence for the presence of the radioactive element in lunar dirt, the researchers said. They announced the discovery recently at the 40th Lunar and Planetary Conference and at the Proceedings of the International Workshop Advances in Cosmic Ray Science.

The revelation suggests that nuclear power plants could be built on the moon, or even that Earth’s satellite could serve as a mining source for uranium needed back home.

The Japanese Kaguya spacecraft, which was launched in 2007, detected uranium with a gamma-ray spectrometer. Scientists are using the instrument to create maps of the moon’s surface composition, showing the presence of thorium, potassium, oxygen, magnesium, silicon, calcium, titanium and iron.

“We’ve already gotten uranium results, which have never been reported before,” said Robert Reedy, a senior scientist at the Tucson-based Planetary Science Institute, and a member of the Kaguya science team. “We’re getting more new elements and refining and confirming results found on the old maps.”

The findings could help decide where to build future lunar colonies, since manned outposts will need energy, and could potentially derive it from nuclear power plants.

Furthermore, since uranium supplies on Earth are scarce, mining uranium on the moon to satisfy our energy needs at home could prove lucrative.

Kaguya, officially named SELENE (“Selenological and Engineering Explorer”), crashed into the lunar surface at the end of its mission on June 10.

Via space.com

For 15 years, scientists have benefited from data gleaned by U.S. classified satellites of natural fireball events in Earth’s atmosphere — but no longer.

A recent U.S. military policy decision now explicitly states that observations by hush-hush government spacecraft of incoming bolides and fireballs are classified secret and are not to be released, SPACE.com has learned.

The satellites’ main objectives include detecting nuclear bomb tests, and their characterizations of asteroids and lesser meteoroids as they crash through the atmosphere has been a byproduct data bonanza for scientists.

The upshot: Space rocks that explode in the atmosphere are now classified.

“It’s baffling to us why this would suddenly change,” said one scientist familiar with the work. “It’s unfortunate because there was this great synergy … a very good cooperative arrangement. Systems were put into dual-use mode where a lot of science was getting done that couldn’t be done any other way. It’s a regrettable change in policy.”

Scientists say not only will research into the threat from space be hampered, but public understanding of sometimes dramatic sky explosions will be diminished, perhaps leading to hype and fear of the unknown.

Incoming!
Most “shooting stars” are caused by natural space debris no larger than peas. But routinely, rocks as big as basketballs and even small cars crash into the atmosphere. Most vaporize or explode on the way in, but some reach the surface or explode above the surface. Understandably, scientists want to know about these events so they can better predict the risk here on Earth.

Yet because the world is two-thirds ocean, most incoming objects aren’t visible to observers on the ground. Many other incoming space rocks go unnoticed because daylight drowns them out.

Over the last decade or so, hundreds of these events have been spotted by the classified satellites. Priceless observational information derived from the spacecraft were made quickly available, giving researchers such insights as time, a location, height above the surface, as well as light-curves to help pin down the amount of energy churned out from the fireballs.

And in the shaky world we now live, it’s nice to know that a sky-high detonation is natural versus a nuclear weapon blast.

Where the space-based surveillance truly shines is over remote stretches of ocean – far away from the prospect of ground-based data collection.

But all that ended within the last few months, leaving scientists blind-sided and miffed by the shift in policy. The hope is that the policy decision will be revisited and overturned.

Critical importance
“The fireball data from military or surveillance assets have been of critical importance for assessing the impact hazard,” said David Morrison, a Near Earth Object (NEO) scientist at NASA’s Ames Research Center. He noted that his views are his own, not as a NASA spokesperson.

The size of the average largest atmospheric impact from small asteroids is a key piece of experimental data to anchor the low-energy end of the power-law distribution of impactors, from asteroids greater than 6 miles (10 kilometers) in diameter down to the meter scale, Morrison told SPACE.com.

“These fireball data together with astronomical observations of larger near-Earth asteroids define the nature of the impact hazard and allow rational planning to deal with this issue,” Morrison said.

Morrison said that fireball data are today playing additional important roles.

As example, the fireball data together with infrasound allowed scientists to verify the approximate size and energy of the unique Carancas impact in the Altiplano — on the Peru-Bolivia border — on Sept. 15, 2007.

Fireball information also played an important part in the story of the small asteroid 2008 TC3, Morrison said. That was the first-ever case of the astronomical detection of a small asteroid before it hit last year. The fireball data were key for locating the impact point and the subsequent recovery of fragments from this impact.

Link in public understanding
Astronomers are closing in on a years-long effort to find most of the potentially devastating large asteroids in our neck of the cosmic woods, those that could cause widespread regional or global devastation. Now they plan to look for the smaller stuff.

So it is ironic that the availability of these fireball data should be curtailed just at the time the NEO program is moving toward surveying the small impactors that are most likely to be picked up in the fireball monitoring program, Morrision said.

“These data have been available to the scientific community for the past decade,” he said. “It is unfortunate this information is shut off just when it is becoming more valuable to the community interested in characterizing near Earth asteroids and protecting our planet from asteroid impacts.”

The newly issued policy edict by the U.S. military of reporting fireball observations from satellites also caught the attention of Clark Chapman, a planetary scientist and asteroid impact expert at Southwest Research Institute in Boulder, Colo.

“I think that this information is very important to make public,” Chapman told SPACE.com.

“More important than the scientific value, I think, is that these rare, bright fireballs provide a link in public understanding to the asteroid impact hazard posed by still larger and less frequent asteroids,” Chapman explained.

Those objects are witnessed by unsuspecting people in far-flung places, Chapman said, often generating incorrect and exaggerated reports.

“The grounding achieved by associating these reports by untrained observers with the satellite measurements is very useful for calibrating the observer reports and closing the loop with folks who think they have seen something mysterious and extraordinary,” Chapman said.

Via MSNBC

Cameras aboard the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) probe took more than 1,200 images of the surface, including details of a mammoth well-preserved 692-km impact basin that shows signs of a volcanic past.

The so-called Rembrandt basin is the first such geological feature observed on Mercury where the ground is well exposed and not covered by a thick layer of volcanic ash, like most of the planet’s other features.

“This basin formed about 3.9 billion years ago, near the end of the period of heavy bombardment of the inner Solar System,” said Thomas Watters from the Smithsonian Institution in Washington DC, a lead author of one of the studies, all of which are published in today’s edition of the U.S. journal, Science.

“This second Mercury flyby provided a number of new findings,” said Sean Solomon, the probe’s principal investigator from the Washington-based Carnegie Institution. “One of the biggest surprises was how strongly the dynamics of the planet’s magnetic field-solar wind interaction changed from what we saw during the first Mercury flyby in January 2008,” he added. “The discovery of a large and unusually well preserved impact basin shows concentrated volcanic and deformational activity.”

“This second Mercury flyby provided a number of new findings,” said Sean Solomon, the probe’s principal investigator from the Carnegie Institution of Washington. “One of the biggest surprises was how strongly the dynamics of the planet’s magnetic field–solar wind interaction changed from what we saw during the first Mercury flyby in January 2008. The discovery of a large and unusually well preserved impact basin shows concentrated volcanic and deformational activity.”

The spacecraft also made the first detection of magnesium in Mercury’s thin atmosphere, known as an exosphere. While finding it was not surprising, the amounts and distribution was unexpected. The instrument also measured other exospheric constituents, including calcium and sodium.

“This is an example of the kind of individual discoveries that the science team will piece together to give us a new picture of how the planet formed and evolved,” said William McClintock, co-investigator and lead author of one of the four papers. McClintock, who is from the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder, suspects that additional metallic elements from the surface, including aluminum, iron and silicon, also contribute to the exosphere.

The variability that the spacecraft observed in Mercury’s magnetosphere, the volume of space dominated by the planet’s magnetic field, so far supports the hypothesis that the great day-to-day changes in Mercury’s atmosphere may be a result of changes in the shielding provided by the magnetosphere.

“The spacecraft observed a radically different magnetosphere at Mercury during its second flyby compared with its earlier January 14 [2009] encounter,” said James Slavin from NASA’s Goddard Space Flight Centre in Greenbelt, Maryland. “During the first flyby, important discoveries were made, but scientists didn’t detect any dynamic features. The second flyby witnessed a totally different situation.”

Using revolutionary image-capturing technology and a laser altimeter to survey the ground, MESSENGER revealed like never before 30 per cent of the mysterious planet.

In a grand feat of engineering, the probe soared past the innermost planet’s equator at an altitude of 201 km at a speed of 23,818 km/h.

Combined with data from the first flyby and from Mariner 10, which made three passes in 1974 and 1975, the latest coverage means scientists have now seen about 95 per cent of the planet. The probe is on course to make its third flyby on 29 September 2009.

Mercury is the closest of all the planets to the Sun, and because of the high-risks of its proximity – the Sun’s enormous gravitational pull, and massively high levels of radiation – it is one of the most mysterious bodies in the Solar System, even though it is relatively close to Earth.

The January 2008 flyby showed scientists that volcanic eruptions produced many of Mercury’s expansive plains, littered with meteor craters, and that its magnetic field appears to be actively generated in a molten iron core.

Via Cosmos Magazine

Whirling at more than a million miles per hour, these invisible, funnel-shaped solar windstorms carry electrical currents of more than a hundred thousand amps—roughly ten times that of an average lightning strike—scientists announced Thursday.

And they’re huge: up to 44,000 miles (70,000 kilometers) long and wide enough to envelop Earth.

Led by the University of California astrophysicist Andreas Keiling, scientists have made the most detailed measurements yet of the space tornadoes, also known as substorm current wedges.
Their results shed light on how space tornadoes help spark auroras, also known as the southern or northern lights—the glowing colors that light up the night in polar regions.

(Related: “Aurora ‘Power Surges’ Triggered by Magnetic Explosions.”)

The findings were made as part of the NASA’s THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission. THEMIS links 5 spacecraft and 20 ground observatories to measure how solar winds (charged particles from the sun) interact with Earth’s magnetic field.

(Related: “Earth Atmosphere ‘Breathes,’ Thanks to Solar Winds”).

“It is the first time that measurements from ground-based instruments and spacecraft have been combined in this way, and it gives us the most detailed picture yet” about the way our magnetic field responds to solar wind, said Timothy Horbury, a space physicist at Imperial College London, who wasn’t involved in the study.

Spinning Up Auroras

As well as revealing the vast size and speed of these rotating plasmas of ionized gas, the team has pinpointed how space tornadoes kick-start the auroras we see on Earth.

“The tornado appears to ignite the aurora,” said study leader Keiling, who presented the findings at a European Geosciences Union meeting in Vienna, Austria.

Barrages of the wind’s charged particles hit the dayside of Earth, then flow around the planet, stretching our magnetic field into a tail—or magnetotail—extending away from the sun.

A magnetotail is “like a rubber band being stretched and snapped back again. This creates lots of turbulence and forms the tornado,” Keiling said.

Stanley Cowley, a solar and planetary physicist at the University of Leicester, U.K., noted that “the connection between aurora and these storms has been known about for 40 years.”

What’s new, added Cowley, who was not involved in the new study, are the team’s detailed figures on the sizes, shapes, speeds, amperage, and frequency of the space tornadoes.

Space Tornadoes: Fast, Furious—And Frequent

The new measurements show that a space tornado forms roughly every three hours and takes just one minute to reach Earth’s ionosphere—our outermost atmospheric layer, between 62 and 250 miles (100 and 400 kilometers) above the ground.

Auroras are created when the electrons inside the tornadoes collide with particles in the ionosphere, releasing energy and making the molecules glow.

Unlike their counterparts on Earth, space tornadoes are not directly dangerous to humans.

But “sometimes [space tornadoes] generate large currents in conducting structures”—such as power transformers—”on the ground,” Keiling said. And in near space, the storms can disrupt satellite communications, including GPS.

Via National Geographic

In what could be an attempt to trump Jesus of Nazareth’s record for divine Easter resurrections, NASA has said its Mars Exploration Rover Spirit mysteriously rebooted twice during the holiday weekend.

“While we don’t have an explanation yet, we do know that Spirit’s batteries are charged, the solar arrays are producing energy and temperatures are well within allowable ranges,” said John Callas of NASA’s Jet Propulsion Laboratory in a statement.

“The rover is in a stable operation state called automode and taking care of itself. It could stay in this stable mode for some time if necessary while we diagnose the problem.”

May we suggest three days will do the trick?

The (perhaps now-Holy) Spirit was able to communicate with controllers Friday, Saturday, and Sunday, but some of the communication sessions were “irregular,” NASA reported. One of the computer resets occurred while the rover was using its pointable high-gain dish antenna, but the scientists are sure its the problem.

Fortunately, the long-in-tooth rover also sports an immovable low-gain antenna that communicates back to Earth at a slower data rate. It also can relay messages off Mars orbiters using a separate ultra-high frequency (UHF) transceiver system.

“To avoid potential problems using the pointable antenna, we might consider for the time being just communicating by UHF relay or using the low-gan antenna,” Callas stated.

Spirit’s onboard software has been updated several times during its three-month mission – which actually ended five years ago – as well as its extended scientific puttering about the Martian landscape since then. Boffins also suspect the problem could be with Spirits new software, but the same software is operating on Spirit’s twin-rover Opportunity without problems.

Diagnosis: miracle. Or maybe something boring like old age.

“We are aware of the reality that we have an aging rover, and there may be age-related effects here,” Callas said. ®

Via The Register

It Is midnight on 22 September 2012 and the skies above Manhattan are filled with a flickering curtain of colourful light. Few New Yorkers have seen the aurora this far south but their fascination is short-lived. Within a few seconds, electric bulbs dim and flicker, then become unusually bright for a fleeting moment. Then all the lights in the state go out. Within 90 seconds, the entire eastern half of the US is without power.

A year later and millions of Americans are dead and the nation’s infrastructure lies in tatters. The World Bank declares America a developing nation. Europe, Scandinavia, China and Japan are also struggling to recover from the same fateful event – a violent storm, 150 million kilometres away on the surface of the sun.

It sounds ridiculous. Surely the sun couldn’t create so profound a disaster on Earth. Yet an extraordinary report funded by NASA and issued by the US National Academy of Sciences (NAS) in January this year claims it could do just that.

Over the last few decades, western civilisations have busily sown the seeds of their own destruction. Our modern way of life, with its reliance on technology, has unwittingly exposed us to an extraordinary danger: plasma balls spewed from the surface of the sun could wipe out our power grids, with catastrophic consequences.

The projections of just how catastrophic make chilling reading. “We’re moving closer and closer to the edge of a possible disaster,” says Daniel Baker, a space weather expert based at the University of Colorado in Boulder, and chair of the NAS committee responsible for the report.

It is hard to conceive of the sun wiping out a large amount of our hard-earned progress. Nevertheless, it is possible. The surface of the sun is a roiling mass of plasma – charged high-energy particles – some of which escape the surface and travel through space as the solar wind. From time to time, that wind carries a billion-tonne glob of plasma, a fireball known as a coronal mass ejection (see “When hell comes to Earth”). If one should hit the Earth’s magnetic shield, the result could be truly devastating.

The incursion of the plasma into our atmosphere causes rapid changes in the configuration of Earth’s magnetic field which, in turn, induce currents in the long wires of the power grids. The grids were not built to handle this sort of direct current electricity. The greatest danger is at the step-up and step-down transformers used to convert power from its transport voltage to domestically useful voltage. The increased DC current creates strong magnetic fields that saturate a transformer’s magnetic core. The result is runaway current in the transformer’s copper wiring, which rapidly heats up and melts. This is exactly what happened in the Canadian province of Quebec in March 1989, and six million people spent 9 hours without electricity. But things could get much, much worse than that.

Worse than Katrina

The most serious space weather event in history happened in 1859. It is known as the Carrington event, after the British amateur astronomer Richard Carrington, who was the first to note its cause: “two patches of intensely bright and white light” emanating from a large group of sunspots. The Carrington event comprised eight days of severe space weather.

There were eyewitness accounts of stunning auroras, even at equatorial latitudes. The world’s telegraph networks experienced severe disruptions, and Victorian magnetometers were driven off the scale.

Though a solar outburst could conceivably be more powerful, “we haven’t found an example of anything worse than a Carrington event”, says James Green, head of NASA’s planetary division and an expert on the events of 1859. “From a scientific perspective, that would be the one that we’d want to survive.” However, the prognosis from the NAS analysis is that, thanks to our technological prowess, many of us may not.

There are two problems to face. The first is the modern electricity grid, which is designed to operate at ever higher voltages over ever larger areas. Though this provides a more efficient way to run the electricity networks, minimising power losses and wastage through overproduction, it has made them much more vulnerable to space weather. The high-power grids act as particularly efficient antennas, channelling enormous direct currents into the power transformers.

The second problem is the grid’s interdependence with the systems that support our lives: water and sewage treatment, supermarket delivery infrastructures, power station controls, financial markets and many others all rely on electricity. Put the two together, and it is clear that a repeat of the Carrington event could produce a catastrophe the likes of which the world has never seen. “It’s just the opposite of how we usually think of natural disasters,” says John Kappenman, a power industry analyst with the Metatech Corporation of Goleta, California, and an advisor to the NAS committee that produced the report. “Usually the less developed regions of the world are most vulnerable, not the highly sophisticated technological regions.”

According to the NAS report, a severe space weather event in the US could induce ground currents that would knock out 300 key transformers within about 90 seconds, cutting off the power for more than 130 million people (see map). From that moment, the clock is ticking for America.

First to go – immediately for some people – is drinkable water. Anyone living in a high-rise apartment, where water has to be pumped to reach them, would be cut off straight away. For the rest, drinking water will still come through the taps for maybe half a day. With no electricity to pump water from reservoirs, there is no more after that.

There is simply no electrically powered transport: no trains, underground or overground. Our just-in-time culture for delivery networks may represent the pinnacle of efficiency, but it means that supermarket shelves would empty very quickly – delivery trucks could only keep running until their tanks ran out of fuel, and there is no electricity to pump any more from the underground tanks at filling stations.

Back-up generators would run at pivotal sites – but only until their fuel ran out. For hospitals, that would mean about 72 hours of running a bare-bones, essential care only, service. After that, no more modern healthcare.

72 hours of healthcare remaining
The truly shocking finding is that this whole situation would not improve for months, maybe years: melted transformer hubs cannot be repaired, only replaced. “From the surveys I’ve done, you might have a few spare transformers around, but installing a new one takes a well-trained crew a week or more,” says Kappenman. “A major electrical utility might have one suitably trained crew, maybe two.”

Within a month, then, the handful of spare transformers would be used up. The rest will have to be built to order, something that can take up to 12 months.

Even when some systems are capable of receiving power again, there is no guarantee there will be any to deliver. Almost all natural gas and fuel pipelines require electricity to operate. Coal-fired power stations usually keep reserves to last 30 days, but with no transport systems running to bring more fuel, there will be no electricity in the second month.

30 days of coal left
Nuclear power stations wouldn’t fare much better. They are programmed to shut down in the event of serious grid problems and are not allowed to restart until the power grid is up and running.

With no power for heating, cooling or refrigeration systems, people could begin to die within days. There is immediate danger for those who rely on medication. Lose power to New Jersey, for instance, and you have lost a major centre of production of pharmaceuticals for the entire US. Perishable medications such as insulin will soon be in short supply. “In the US alone there are a million people with diabetes,” Kappenman says. “Shut down production, distribution and storage and you put all those lives at risk in very short order.”

Help is not coming any time soon, either. If it is dark from the eastern seaboard to Chicago, some affected areas are hundreds, maybe thousands of miles away from anyone who might help. And those willing to help are likely to be ill-equipped to deal with the sheer scale of the disaster. “If a Carrington event happened now, it would be like a hurricane Katrina, but 10 times worse,” says Paul Kintner, a plasma physicist at Cornell University in Ithaca, New York.

In reality, it would be much worse than that. Hurricane Katrina’s societal and economic impact has been measured at $81 billion to $125 billion. According to the NAS report, the impact of what it terms a “severe geomagnetic storm scenario” could be as high as $2 trillion. And that’s just the first year after the storm. The NAS puts the recovery time at four to 10 years. It is questionable whether the US would ever bounce back.

4-10 years to recover
“I don’t think the NAS report is scaremongering,” says Mike Hapgood, who chairs the European Space Agency’s space weather team. Green agrees. “Scientists are conservative by nature and this group is really thoughtful,” he says. “This is a fair and balanced report.”

Such nightmare scenarios are not restricted to North America. High latitude nations such as Sweden and Norway have been aware for a while that, while regular views of the aurora are pretty, they are also reminders of an ever-present threat to their electricity grids. However, the trend towards installing extremely high voltage grids means that lower latitude countries are also at risk. For example, China is on the way to implementing a 1000-kilovolt electrical grid, twice the voltage of the US grid. This would be a superb conduit for space weather-induced disaster because the grid’s efficiency to act as an antenna rises as the voltage between the grid and the ground increases. “China is going to discover at some point that they have a problem,” Kappenman says.

Neither is Europe sufficiently prepared. Responsibility for dealing with space weather issues is “very fragmented” in Europe, says Hapgood.

Europe’s electricity grids, on the other hand, are highly interconnected and extremely vulnerable to cascading failures. In 2006, the routine switch-off of a small part of Germany’s grid – to let a ship pass safely under high-voltage cables – caused a cascade power failure across western Europe. In France alone, five million people were left without electricity for two hours. “These systems are so complicated we don’t fully understand the effects of twiddling at one place,” Hapgood says. “Most of the time it’s alright, but occasionally it will get you.”

The good news is that, given enough warning, the utility companies can take precautions, such as adjusting voltages and loads, and restricting transfers of energy so that sudden spikes in current don’t cause cascade failures. There is still more bad news, however. Our early warning system is becoming more unreliable by the day.

By far the most important indicator of incoming space weather is NASA’s Advanced Composition Explorer (ACE). The probe, launched in 1997, has a solar orbit that keeps it directly between the sun and Earth. Its uninterrupted view of the sun means it gives us continuous reports on the direction and velocity of the solar wind and other streams of charged particles that flow past its sensors. ACE can provide between 15 and 45 minutes’ warning of any incoming geomagnetic storms. The power companies need about 15 minutes to prepare their systems for a critical event, so that would seem passable.

15 minutes’ warning
However, observations of the sun and magnetometer readings during the Carrington event shows that the coronal mass ejection was travelling so fast it took less than 15 minutes to get from where ACE is positioned to Earth. “It arrived faster than we can do anything,” Hapgood says.

There is another problem. ACE is 11 years old, and operating well beyond its planned lifespan. The onboard detectors are not as sensitive as they used to be, and there is no telling when they will finally give up the ghost. Furthermore, its sensors become saturated in the event of a really powerful solar flare. “It was built to look at average conditions rather than extremes,” Baker says.

He was part of a space weather commission that three years ago warned about the problems of relying on ACE. “It’s been on my mind for a long time,” he says. “To not have a spare, or a strategy to replace it if and when it should fail, is rather foolish.”

There is no replacement for ACE due any time soon. Other solar observation satellites, such as the Solar and Heliospheric Observatory (SOHO) can provide some warning, but with less detailed information and – crucially – much later. “It’s quite hard to assess what the impact of losing ACE will be,” Hapgood says. “We will largely lose the early warning capability.”

The world will, most probably, yawn at the prospect of a devastating solar storm until it happens. Kintner says his students show a “deep indifference” when he lectures on the impact of space weather. But if policy-makers show a similar indifference in the face of the latest NAS report, it could cost tens of millions of lives, Kappenman reckons. “It could conceivably be the worst natural disaster possible,” he says.

The report outlines the worst case scenario for the US. The “perfect storm” is most likely on a spring or autumn night in a year of heightened solar activity – something like 2012. Around the equinoxes, the orientation of the Earth’s field to the sun makes us particularly vulnerable to a plasma strike.

What’s more, at these times of year, electricity demand is relatively low because no one needs too much heating or air conditioning. With only a handful of the US grid’s power stations running, the system relies on computer algorithms shunting large amounts of power around the grid and this leaves the network highly vulnerable to sudden spikes.

If ACE has failed by then, or a plasma ball flies at us too fast for any warning from ACE to reach us, the consequences could be staggering. “A really large storm could be a planetary disaster,” Kappenman says.

So what should be done? No one knows yet – the report is meant to spark that conversation. Baker is worried, though, that the odds are stacked against that conversation really getting started. As the NAS report notes, it is terribly difficult to inspire people to prepare for a potential crisis that has never happened before and may not happen for decades to come. “It takes a lot of effort to educate policy-makers, and that is especially true with these low-frequency events,” he says.

We should learn the lessons of hurricane Katrina, though, and realise that “unlikely” doesn’t mean “won’t happen”. Especially when the stakes are so high. The fact is, it could come in the next three or four years – and with devastating effects. “The Carrington event happened during a mediocre, ho-hum solar cycle,” Kintner says. “It came out of nowhere, so we just don’t know when something like that is going to happen again.”

Via New Scientist

The Sun itself will begin its death throes in about 5 billion years, when it starts to swell into a red giant star. Though it’s not clear exactly what its planetary nebula will look like – its shape will likely be sculpted by factors such as the Sun’s future magnetic field – observations of the 1600 or so known planetary nebulae suggest our star will go out in a blaze of glory.

Lasting no more than a few tens of thousands of years, planetary nebulae help seed space with heavier chemical elements that can be incorporated into the next generation of stars. A new book called Galaxy: Exploring the Milky Way by Stuart Clark features some absolutely spectacular images of these nebulae.

To see stunning images of planetary nebulae click here

Via New Scientist

North Korea put its armed forces on standby Monday and threatened ”a war” if anyone tries to shoot down what regional powers suspect is an imminent test-firing of a long-range missile.

Pyongyang also cut off a military hot line with the South, causing a complete shutdown of their border and stranding hundreds of South Koreans working in an industrial zone in the North Korean border city of Kaesong.

Monday’s warning — the latest barrage of threats from the communist regime — came as U.S. and South Korean troops kicked off annual war games across the South, exercises the North has condemned as preparation for an invasion. Pyongyang last week threatened South Korean passenger planes flying near its airspace during the drills.

Analysts say the regime is trying to grab President Barack Obama’s attention as his administration formulates its North Korea policy.

The North also indicated it was pushing ahead with plans to send a communications satellite into space, a provocative launch neighboring governments believe could be a cover for a long-range missile capable of reaching Alaska.

U.S. and Japanese officials have suggested they could shoot down a North Korean missile if necessary, further incensing Pyongyang.

”Shooting our satellite for peaceful purposes will precisely mean a war,” the general staff of the North’s military said in a statement carried Monday by the official Korean Central News Agency.

Any interception will draw ”a just retaliatory strike operation not only against all the interceptor means involved but against the strongholds” of the U.S., Japan and South Korea, it said.

The North has ordered military personnel ”fully combat ready,” KCNA said in a separate dispatch.

Obama’s special envoy on North Korea again urged Pyongyang not to fire a missile, which he said would be an ”extremely ill-advised” move.

”Whether they describe it as a satellite launch or something else makes no difference” since both would violate a U.N. Security Council resolution banning the North from ballistic activity, Stephen Bosworth told reporters after talks with his South Korean counterpart.

South Korea’s Defense Ministry spokesman Won Tae-jae downplayed the North’s threats as ”rhetoric” but said the country’s military was ready to deal with any contingencies.

Analysts say a satellite or missile launch could occur late this month or in early April when the North’s new legislature, elected Sunday, is expected to convene its first session to confirm Kim Jong Il as leader.

Ties between the two Koreas have plunged since South Korean President Lee Myung-bak took office a year ago halting aid unless the North fulfills an international promise to dismantle its nuclear program.

In retaliation, North Korea suspended the reconciliation process and key joint projects with Seoul, and has stepped up the stream of belligerence toward the South.

Severing the military hot line for the duration of the 12-day joint U.S.-South Korean military exercises leaves the two Koreas without any means of communication at a time of heightened tensions.

The two Koreas use the hot line to exchange information about goods and people crossing into Kaesong. Its suspension halted traffic and stranded about 570 South Koreans who were working in Kaesong.

About 80 had planned to return to the South on Monday but were stuck there overnight since they cannot travel after nightfall. Earlier, some 700 South Koreans who intended to go to Kaesong on Monday were unable to cross the border, the Unification Ministry said.

All South Koreans in Kaesong are safe, the ministry said as it called on Pyongyang to restore the hot line immediately.

The two Koreas technically remain in a state of war since their three-year conflict ended in a cease-fire, not a peace treaty, in 1953. Hundreds of thousands of troops are amassed on each side of the Demilitarized Zone separating the two Koreas, making the Korean border one of the world’s most heavily armed.

The United States, which has 28,5000 troops in South Korea, routinely holds military exercises with the South. Pyongyang routinely condemns them as rehearsals for invasion despite assurances from Seoul and Washington that the drills are defensive.

The exercises, which will involve some 26,000 U.S. troops, an unspecified number of South Korean soldiers and a U.S. aircraft carrier, are ”not tied in any way to any political or real world event,” Gen. Walter Sharp, commander of the U.S. troops, said Monday.

Via The New York Times