According to observations from the Tihany Magnetic Observatory in Hungary, the indices used by scientists to assess the Sun's geomagnetic perturbations to the Earth are unable to detect some of these events, which could put both power supply and communication networks at risk. The Tihany Magnetic Observatory registered a solar storm similar to the largest one ever recorded while other observatories were completely unaware of the event.
In 1859 the largest and most powerful solar storm ever recorded, also known as the Carrington Event or the Carrington Flare in honour of the English Astronomer Richard Carrington who observed it, was detected at the Colaba Observatory in India. This solar storm allowed for the observation of auroras at latitudes as low as Madrid and even the Caribbean Sea. However, the storm was also the cause of power outages and fires at telegraph system facilities all over Europe and North America. Ever since, geomagnetic storms caused by the Sun pose a serious threat to a society that is increasingly dependent on technology, in addition to directly posing serious danger to power and communication networks. In order to avoid this risk scientists have developed several indices that can help to both analyse and predict this phenomenon.
One of the most widely used indices for measuring geomagnetic storms is the Dst (Disturbance storm time), which is obtained every hour by averaging the data recorded at four observatories: Hermanus (South Africa), Kakioka (Japan), Honolulu (Hawaii, USA) and San Juan (Puerto Rico).
A more precise version called SYM-H -which assesses the horizontal component of the Earth's magnetic field- utilises the information collected from even more observatories and a one-minute time resolution. Scientists can track the effects of large solar storms by using these two indices wherein latitude (the angular distance to the equator) is the prevailing data in magnetic records. One of these large solar storms was the Halloween Solar Storm that took place between October and November of 2003.
Nevertheless, neither Dst nor SYM-H was able to detect the magnetic perturbation that affected the Earth precisely at that time, specifically on 29 October 2003. This solar event was extraordinarily similar to the Carrington Flare of 1859. The Halloween Solar Storm affected power plants both in Sweden and South Africa where several transformers were burnt.
The event was recorded at the Tihany Magnetic Observatory in Hungary. A team of researchers from the University of Alcalá has now analysed the official indices' failure to detect that event, and is now reporting on the potential consequences.
"One of the conclusions is that the indices commonly used by scientists -such as Dst or SYM-H, which are based on an overall perspective of the Earth and obtained by calculating averages,- failed to detect such an important event, and they most likely would have failed to detect the Carrington Event as well," explains Consuelo Cid, the lead author.
The study, published by the Journal of Space Weather and Space Climate, suggests that the scientific community could be mistaken in their calculation of the data average from different observatories around the world. This may be attributable to the fact that positive and negative magnetic disturbances cancel each other out, meaning that the true magnetic disturbance in a region disappears. In addition, the disturbance depends greatly on the local time (longitude), although other scientists postulate that it depends largely on the latitude.
"A Carrington-like event may occur more often than we expect; actually, it might have already happened without us even realising it," notes Cid, who points out the need to develop local indices that are truly useful to companies that may be affected by these disturbances, such as electric companies.
In fact, her team has developed the Local Disturbance index for Spain (LDiñ) which calculates the geomagnetic perturbation in Spanish territory. It is calculated based on the magnetic field recorded at the San Pablo Observatory in Toledo, which belongs to the Spanish National Geographic Institute.
"An index similar to LDiñ could be used in neighbouring countries, such as Portugal, France and Italy; likewise, indices adjusted to each region could be developed for use in other parts of the world," points out the researcher, who insists on the need to collaborate with implicated companies, just as her research team collaborated with Spain's national power grid company, Red Eléctrica Española.
How Did The Halloween Asteroid Sneak Up On Us?
Fortunately it's not headed for Earth
Earth is getting a very large trick-or-treater this Halloween.
On October 31, an approximately 1,300-foot asteroid will hurtle by at about 1.3 times the distance of the Moon. It'll likely be our closest encounter with such a huge space rock until 2027.
The timing of 2015 TB145 (the "Halloween Asteroid") is spooky, but so is the fact that it managed to sneak up on us. We didn't even know it existed until October 10--just 21 days before its arrival.
Luckily, 2015 TB145 will remain at a safe distance from Earth. But if it were on a crash course with Earth, it would take more than a handful of candy to keep it from defacing our home.
"If it were headed directly for Earth, that would have been too late to do anything about it," Paul Chodas, who heads up NASA's Near Earth Object program, tells Popular Science. And while that's not a likely event, it's certainly possible. "An asteroid of this size is really difficult to deflect with only 20 days warning."
Why Didn't We See It Coming?
The "Halloween asteroid" was discovered by Pan-STARRS--a large telescope in Hawaii that searches the skies for comets, asteroids, and other moving objects. While it's fairly common for Pan-STARRS to discover these objects, "it's not common to discover something as big as this passing so close to Earth," explains Richard Wainscoat, Pan-STARRS principal investigator.
Asteroid 2015 TB145 was difficult to spot because it has a strange orbit, he says.
The Sun and the planets are arranged in a flat disk shape. This is called the ecliptic plane. Most of the asteroids in the belt between Mars and Jupiter can be found along the ecliptic plane, too, but the "Halloween asteroid" is different. If you could look at the solar system from the side, 2015 TB145 cuts a path at a 40-degree angle to the line of the ecliptic plane.
"So it's in a region of sky where there aren't many asteroids, a region of sky that's not searched as often," says Chodas. "It's a tribute to the thoroughness of NASA's surveys that, even though it was difficult to detect, we caught it."
"I wouldn't expect a large number of asteroids to be in this kind of orbit."
The asteroid also spends a lot of time away from Earth. It orbits the Sun every three years, but like other asteroids with oval-shaped orbits, it doesn't move at a constant velocity. When it is furthest from the inner solar system (and Earth) it moves slowly. At that point it is far away, faint and hard to detect. And when it swings back near Earth, the Sun's gravity speeds it up and it zips past us. The asteroid spends less than 5 percent of its time in the inner solar system, says Chodas.
"The last time it made a close approach like this was in 1975, when we were not really searching the sky," he says. At that time, the asteroid came near Earth's track around the Sun, but at a time when Earth was in a different spot along the track.
"I wouldn't expect a large number of asteroids to be in this kind of orbit," says Chodas. "It's quite peculiar… The majority are in orbits that are much easier to detect."
What To Expect
Asteroid 2015 TB145 is expected to reach its closest approach to Earth at about 1:18 pm Eastern. It'll blast past us at a speed of about 78,300 miles an hour, and should be bright enough to see with a decent telescope and a star chart.
The asteroid's proximity will give scientists an excellent chance to study it. Scientists hope to image it with a resolution as high as 6.5 feet (2 meters) per pixel, and radar measurements will help shed light on the asteroid's precise size and composition. So far all we really know is that it's somewhere around 1,050 to 2,100 feet (320 to 640 meters) in diameter.
The 'asteroid' could be a dead comet
"Radar measurements will also reveal whether it has a moon," says Wainscoat. "A lot of objects like this one turn out to have companions, so it would not be a surprise at all if it turned out to have a companion. If it does, then the orbital motion of the companion might yield the mass of the asteroid, which in turn would yield its density and some idea of its composition."
Chodas speculates that the asteroid could actually be a dead comet--the rocky remains after all of the comet's ice trailed off behind it.
But there's another important reason to observe object 2015 TB145. "The more asteroids we can see up close," says Chodas, "the more we'll learn about them, and the better prepared we'll be if we ever need to deflect one."
A Threat To Earth?
The "Halloween asteroid" won't hit Earth. But what about others like it?
Although our telescopes have spotted about 90 percent of the kilometer-sized (3,300-foot) asteroids that would endanger life on Earth, the medium-sized rocks like 2015 TB145 are harder to track. Chodas estimates that scientists have only spotted about 40 percent of asteroids around the size of 2015 TB145.
That's not good, because even a 1,300-foot (400-meter) asteroid could smack Earth like 2800 metric tons of dynamite, leaving behind a crater 3.7 miles wide. "If an asteroid of this size strikes the Earth it would produce continental-scale devastation," says Chodas, though, "not the global-scale catastrophe that an impact of a kilometer-size asteroid would produce."
Lucky for us, rocks the size of the "Halloween asteroid" only hit the Earth about once every hundred thousand years or so. So the odds of an impact are pretty small. Still, NASA wants to find as many of these medium-sized asteroids as possible. With bigger telescopes coming online soon, Chodas says scientists could potentially track down 90 percent of them by the mid 2020s.
Expanding The Search
Finding asteroids is partly a matter of luck. Observing more parts of the sky for more time would make it more likely we'll spot potential threats to Earth.
For now, Pan-STARRS is one of few telescopes whose main purpose is to search for asteroids and comets. A second Pan-STARRS telescope could come online soon, which would double the capacity to spot asteroids. "We can cover twice the amount of the sky every month," says Wainscoat. "And we can spend more time searching in the more exotic locations, like where this one was found."
Wainscoat says Pan-STARRS 2 could be fully operational by next year.
Even more promising is the Large Synoptic Survey Telescope (LSST) that's being built in Chile. With its 27-foot aperture and 3200 megapixel camera, it will be able to detect objects as small as 460 feet (140 meters), even if they're very far from Earth. The telescope is expected to begin searching the skies in 2020.
While Pan-STARRS and LSST are optical telescopes, an infrared scope could also be a big help in detecting potential Earth threats.
"I think that an infrared space telescope is needed if we want to get to the 90 percent completion on the 140-meter size range any time soon," says Chodas. "This asteroid could have easily been discovered three years ago when it passed the Earth's orbit not to far from us, but we didn't have any infrared spacecraft looking for asteroids at that time."
Since then, the Wide-field Infrared Survey Explorer telescope has been turned on, and it has discovered tens of thousands of asteroids. However, it won't operate forever. Because WISE is in low Earth orbit, it will slowly fall toward Earth until it's no longer useful.
NEOcam (Near-Earth Object Camera) is a proposed infrared telescope that would potentially track down 10 times more near-Earth objects than we've currently located. NASA recently gave the team some funding to further develop the idea. If the project is selected, it could fly as early as 2020.
And as for what we would do if we ever spotted a large asteroid heading our way … scientists are still trying to figure that out. Chances are, it would involve explosives, just like in the Armageddon--though some scientists think that would just make matters worse by pummeling the Earth with asteroid shrapnel.
"A 400-meter asteroid is pretty hard to blow up, and we don't have missions ready to launch to do that sort of thing," says Chodas.
http://www.popsci.com/how-did-halloween-asteroid-sneak-up-on-us
Earth is in grave danger of being hit by a catastrophic comet shower triggered by the sun, warn scientists
Earth may be in great danger as the sun's path through the galaxy sends comet flying towards our planet, scientists have warned.
Researchers have identified a 26 million-year cycle of meteor impacts that coincides with the timing of mass extinctions over the past 260 million years.
The doomsday events are linked to the motion of the sun and its family of planets through the dense mid-plane of the Milky Way.
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Researchers have identified a 26 million-year cycle of meteor impacts that coincides with the timing of mass extinctions over the past 260 million years. Pictured is a graph showing how the rate of cratering has changed on Earth over time. The arrows indicate the dates of mass extinctions
Gravitational disturbance of the Oort Cloud - a shell of icy objects on the outer edge of the solar system - is believed to lead to periodic showers of comets pouring through the inner region where the Earth resides.
The last of these events is said to have occurred about 11 million years ago, roughly the same time as the Middle Miocene mass extinction
But according to geologist Professor Michael Rampino, it might be wrong to assume that we are living in a completely safe era, millions of years away from the next danger period.
'There is evidence that the comet activity has been high for the last one to two million years, and some comet orbits are perturbed, so we may be in a shower at the present time,' he said.
Earth may be in great danger as the sun's path through the galaxy sends comet flying towards our planet, scientists have warned. The doomsday events are linked to the motion of the sun and its family of planets through the dense mid-plane of the Milky Way
'That would agree with our position near the galactic mid-plane, where perturbations from dark matter etc. would be expected.'
WHAT IS DARK MATTER?
Dark matter surrounds galaxies across the universe, and is invisible because it does not reflect light.
It cannot be seen directly with telescopes, but astronomers know it to be out there because of the gravitational effects it has on the matter we can see.
The European Space Agency says: 'Shine a torch in a completely dark room, and you will see only what the torch illuminates.
'That does not mean that the room around you does not exist.
'Similarly we know dark matter exists but have never observed it directly.'
Scientists are fairly sure it exists and is crucial to the universe, but they do not know what it looks like or where to find it.
Dark matter is the mysterious invisible substance that surrounds galaxies and can only be detected from its gravitational effects.
It is believed to account for more than 80 per cent of all the matter in the universe.
Professor Rampino, from New York University, and colleague Professor Ken Caldeira, from the Carnegie Institution, carried out an analysis of meteor impacts and extinctions using newly available data providing more accurate age estimates.
They found that six mass extinctions linkedwith the timing of heightened periods of impact cratering on Earth.
One of the impacts studied was caused by the large comet or asteroid that struck the Earth 65 million years ago off the Yucatan coast of Mexico and is said to have wiped out the dinosaurs.
Five of the six largest impact craters coincided with mass extinction events, said the scientists writing in the journal Monthly Notices of the Royal Astronomical Society.
'The correlation between the formation of these impacts and extinction events over the past 260 million years is striking and suggests a cause-and-effect relationship,' said Prof Rampino.
'This cosmic cycle of death and destruction has without a doubt affected the history of life on our planet.'
http://www.dailymail.co.uk/sciencetech/article-3287126/Earth-grave-danger-catastrophic-comet-shower-triggered-sun-warn-scientists.html#ixzz3pWGz9r3N
