Deep Space Climate Observatory to provide 'EPIC' views of Earth

NASA has contributed two Earth science instruments for NOAA's space weather observing satellite called the Deep Space Climate Observatory or DSCOVR, set to launch in January 2015. One of the instruments called EPIC or Earth Polychromatic Imaging Camera will image the Earth in one picture, something that hasn't been done before from a satellite. EPIC will also provide valuable atmospheric data.

Currently, to get an entire Earth view, scientists have to piece together images from satellites in orbit. With the launch of the National Oceanic and Atmospheric Administration's (NOAA) DSCOVR and the EPIC instrument, scientists will get pictures of the entire sunlit side of Earth. To get that view, EPIC will orbit the first sun-Earth Lagrange point (L1), 1 million miles from Earth. At this location, four times further than the orbit of the Moon, the gravitational pull of the sun and Earth cancel out providing a stable orbit for DSCOVR. Most other Earth-observing satellites circle the planet within 22,300 miles.

"Unlike personal cameras, EPIC will take images in 10 very narrow wavelength ranges," said Adam Szabo, DSCOVR project scientist at NASA's Goddard Space Flight Center, Greenbelt, Maryland. "Combining these different wavelength images allows the determination of physical quantities like ozone, aerosols, dust and volcanic ash, cloud height, or vegetation cover. These results will be distributed as different publicly available data products allowing their combination with results from other missions."

These data products are of interest to climate science, as well as hydrology, biogeochemistry, and ecology. Data will also provide insight into Earth's energy balance.

EPIC was built by Lockheed Martin's Advanced Technology Center, in Palo Alto, California. It is a 30 centimeter (11.8 inch) telescope that measures in the ultraviolet, and visible areas of the spectrum. EPIC images will have a resolution of between 25 and 35 kilometers (15.5 to 21.7 miles).

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Plasma plumes help shield Earth from damaging solar storms

Earth's magnetic field, or magnetosphere, stretches from the planet's core out into space, where it meets the solar wind, a stream of charged particles emitted by the sun. For the most part, the magnetosphere acts as a shield to protect Earth from this high-energy solar activity.

But when this field comes into contact with the sun's magnetic field -- a process called "magnetic reconnection" -- powerful electrical currents from the sun can stream into Earth's atmosphere, whipping up geomagnetic storms and space weather phenomena that can affect high-altitude aircraft, as well as astronauts on the International Space Station.

Now scientists at MIT and NASA have identified a process in Earth's magnetosphere that reinforces its shielding effect, keeping incoming solar energy at bay.

By combining observations from the ground and in space, the team observed a plume of low-energy plasma particles that essentially hitches a ride along magnetic field lines -- streaming from Earth's lower atmosphere up to the point, tens of thousands of kilometers above the surface, where the planet's magnetic field connects with that of the sun. In this region, which the scientists call the "merging point," the presence of cold, dense plasma slows magnetic reconnection, blunting the sun's effects on Earth.

"The Earth's magnetic field protects life on the surface from the full impact of these solar outbursts," says John Foster, associate director of MIT's Haystack Observatory. "Reconnection strips away some of our magnetic shield and lets energy leak in, giving us large, violent storms. These plasmas get pulled into space and slow down the reconnection process, so the impact of the sun on the Earth is less violent."

Foster and his colleagues publish their results in this week's issue of Science. The team includes Philip Erickson, principal research scientist at Haystack Observatory, as well as Brian Walsh and David Sibeck at NASA's Goddard Space Flight Center.

Mapping Earth's magnetic shield

For more than a decade, scientists at Haystack Observatory have studied plasma plume phenomena using a ground-based technique called GPS-TEC, in which scientists analyze radio signals transmitted from GPS satellites to more than 1,000 receivers on the ground. Large space-weather events, such as geomagnetic storms, can alter the incoming radio waves -- a distortion that scientists can use to determine the concentration of plasma particles in the upper atmosphere. Using this data, they can produce two-dimensional global maps of atmospheric phenomena, such as plasma plumes.

These ground-based observations have helped shed light on key characteristics of these plumes, such as how often they occur, and what makes some plumes stronger than others. But as Foster notes, this two-dimensional mapping technique gives an estimate only of what space weather might look like in the low-altitude regions of the magnetosphere. To get a more precise, three-dimensional picture of the entire magnetosphere would require observations directly from space.

Toward this end, Foster approached Walsh with data showing a plasma plume emanating from Earth's surface, and extending up into the lower layers of the magnetosphere, during a moderate solar storm in January 2013. Walsh checked the date against the orbital trajectories of three spacecraft that have been circling the Earth to study auroras in the atmosphere.

As it turns out, all three spacecraft crossed the point in the magnetosphere at which Foster had detected a plasma plume from the ground. The team analyzed data from each spacecraft, and found that the same cold, dense plasma plume stretched all the way up to where the solar storm made contact with Earth's magnetic field.

A river of plasma

Foster says the observations from space validate measurements from the ground. What's more, the combination of space- and ground-based data give a highly detailed picture of a natural defensive mechanism in Earth's magnetosphere.

"This higher-density, cold plasma changes about every plasma physics process it comes in contact with," Foster says. "It slows down reconnection, and it can contribute to the generation of waves that, in turn, accelerate particles in other parts of the magnetosphere. So it's a recirculation process, and really fascinating."

Foster likens this plume phenomenon to a "river of particles," and says it is not unlike the Gulf Stream, a powerful ocean current that influences the temperature and other properties of surrounding waters. On an atmospheric scale, he says, plasma particles can behave in a similar way, redistributing throughout the atmosphere to form plumes that "flow through a huge circulation system, with a lot of different consequences."

"What these types of studies are showing is just how dynamic this entire system is," Foster adds.

Journal Reference:

B. M. Walsh, J. C. Foster, P. J. Erickson, D. G. Sibeck. Simultaneous Ground- and Space-Based Observations of the Plasmaspheric Plume and Reconnection. Science, 2014 DOI: 10.1126/science.1247212

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Warming climate may spread drying to a third of earth: Heat, not just rainfall, plays into new projections

Increasing heat is expected to extend dry conditions to far more farmland and cities by the end of the century than changes in rainfall alone, says a new study. Much of the concern about future drought under global warming has focused on rainfall projections, but higher evaporation rates may also play an important role as warmer temperatures wring more moisture from the soil, even in some places where rainfall is forecasted to increase, say the researchers.

The study is one of the first to use the latest climate simulations to model the effects of both changing rainfall and evaporation rates on future drought. Published this month in the journal Climate Dynamics, the study estimates that 12 percent of land will be subject to drought by 2100 through rainfall changes alone; but the drying will spread to 30 percent of land if higher evaporation rates from the added energy and humidity in the atmosphere is considered. An increase in evaporative drying means that even regions expected to get more rain, including important wheat, corn and rice belts in the western United States and southeastern China, will be at risk of drought. The study excludes Antarctica.

"We know from basic physics that warmer temperatures will help to dry things out," said the study's lead author, Benjamin Cook, a climate scientist with joint appointments at Columbia University's Lamont-Doherty Earth Observatory and the NASA Goddard Institute for Space Studies. "Even if precipitation changes in the future are uncertain, there are good reasons to be concerned about water resources."

In its latest climate report, the International Panel on Climate Change (IPCC) warns that soil moisture is expected to decline globally and that already dry regions will be at greater risk of agricultural drought. The IPCC also predicts a strong chance of soil moisture drying in the Mediterranean, southwestern United States and southern African regions, consistent with the Climate Dynamics study.

Using two drought metric formulations, the study authors analyze projections of both rainfall and evaporative demand from the collection of climate model simulations completed for the IPCC's 2013 climate report. Both metrics agree that increased evaporative drying will probably tip marginally wet regions at mid-latitudes like the U.S. Great Plains and a swath of southeastern China into aridity. If precipitation were the only consideration, these great agricultural centers would not be considered at risk of drought. The researchers also say that dry zones in Central America, the Amazon and southern Africa will grow larger. In Europe, the summer aridity of Greece, Turkey, Italy and Spain is expected to extend farther north into continental Europe.

"For agriculture, the moisture balance in the soil is what really matters," said study coauthor Jason Smerdon, a climate scientist at Lamont-Doherty. "If rain increases slightly but temperatures also increase, drought is a potential consequence."

Today, while bad weather periodically lowers crop yields in some places, other regions are typically able to compensate to avert food shortages. In the warmer weather of the future, however, crops in multiple regions could wither simultaneously, the authors suggest. "Food-price shocks could become far more common," said study coauthor Richard Seager, a climate scientist at Lamont-Doherty. Large cities, especially in arid regions, will need to carefully manage their water supplies, he added.

The study builds on an emerging body of research looking at how evaporative demand influences hydroclimate. "It confirms something we've suspected for a long time," said Toby Ault, a climate scientist at Cornell University, who was not involved in the study. "Temperature alone can make drought more widespread. Studies like this give us a few new powerful tools to plan for and adapt to climate change."

Rainfall changes do not tell the whole story, agrees University of New South Wales researcher Steven Sherwood, in a recent Perspectives piece in the leading journal Science. "Many regions will get more rain, but it appears that few will get enough to keep pace with the growing evaporative demand."

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Fierce 2012 magnetic storm just missed us: Earth dodged huge magnetic bullet from the sun

Earth dodged a huge magnetic bullet from the sun on July 23, 2012.

According to University of California, Berkeley, and Chinese researchers, a rapid succession of coronal mass ejections -- the most intense eruptions on the sun -- sent a pulse of magnetized plasma barreling into space and through Earth's orbit. Had the eruption come nine days earlier, it would have hit Earth, potentially wreaking havoc with the electrical grid, disabling satellites and GPS, and disrupting our increasingly electronic lives.

The solar bursts would have enveloped Earth in magnetic fireworks matching the largest magnetic storm ever reported on Earth, the so-called Carrington event of 1859. The dominant mode of communication at that time, the telegraph system, was knocked out across the United States, literally shocking telegraph operators. Meanwhile, the Northern Lights lit up the night sky as far south as Hawaii.

In a paper appearing today (Tuesday, March 18) in the journal Nature Communications, former UC Berkeley postdoctoral fellow and research physicist Ying D. Liu, now a professor at China's State Key Laboratory of Space Weather, UC Berkeley research physicist Janet G. Luhmann and their colleagues report their analysis of the magnetic storm, which was detected by NASA's STEREO A spacecraft.

"Had it hit Earth, it probably would have been like the big one in 1859, but the effect today, with our modern technologies, would have been tremendous," said Luhmann, who is part of the STEREO (Solar Terrestrial Observatory) team and based at UC Berkeley's Space Sciences Laboratory.

A study last year estimated that the cost of a solar storm like the Carrington Event could reach $2.6 trillion worldwide. A considerably smaller event on March 13, 1989, led to the collapse of Canada's Hydro-Quebec power grid and a resulting loss of electricity to six million people for up to nine hours.

"An extreme space weather storm -- a solar superstorm -- is a low-probability, high-consequence event that poses severe threats to critical infrastructures of the modern society," warned Liu, who is with the National Space Science Center of the Chinese Academy of Sciences in Beijing. "The cost of an extreme space weather event, if it hits Earth, could reach trillions of dollars with a potential recovery time of 4-10 years. Therefore, it is paramount to the security and economic interest of the modern society to understand solar superstorms."

Based on their analysis of the 2012 event, Liu, Luhmann and their STEREO colleagues concluded that a huge outburst on the sun on July 22 propelled a magnetic cloud through the solar wind at a peak speed of more than 2,000 kilometers per second -- four times the typical speed of a magnetic storm. It tore through Earth's orbit but, luckily, Earth and the other planets were on the other side of the sun at the time. Any planets in the line of sight would have suffered severe magnetic storms as the magnetic field of the outburst tangled with the planets' own magnetic fields.

The researchers determined that the huge outburst resulted from at least two nearly simultaneous coronal mass ejections (CMEs), which typically release energies equivalent to that of about a billion hydrogen bombs. The speed with which the magnetic cloud plowed through the solar wind was so high, they concluded, because another mass ejection four days earlier had cleared the path of material that would have slowed it down.

"The authors believe this extreme event was due to the interaction of two CMEs separated by only 10 to 15 minutes," said Joe Gurman, the project scientist for STEREO at NASA's Goddard Space Flight Center in Greenbelt, Md.

One reason the event was potentially so dangerous, aside from its high speed, is that it produced a very long-duration, southward-oriented magnetic field, Luhmann said. This orientation drives the largest magnetic storms when they hit Earth because the southward field merges violently with Earth's northward field in a process called reconnection. Storms that normally might dump their energy only at the poles instead dump it into the radiation belts, ionosphere and upper atmosphere and create auroras down to the tropics.

"These gnarly, twisty ropes of magnetic field from coronal mass ejections come blasting from the sun through the ambient solar system, piling up material in front of them, and when this double whammy hits Earth, it skews the Earth's magnetic field to odd directions, dumping energy all around the planet," she said. "Some of us wish Earth had been in the way; what an experiment that would have been."

"People keep saying that these are rare natural hazards, but they are happening in the solar system even though we don't always see them," she added. "It's like with earthquakes -- it is hard to impress upon people the importance of preparing unless you suffer a magnitude 9 earthquake."

All this activity would have been missed if STEREO A -- the STEREO spacecraft ahead of us in Earth's orbit and the twin to STEREO B, which trails in our orbit -- had not been there to record the blast.

The goal of STEREO and other satellites probing the magnetic fields of the sun and Earth is to understand how and why the sun sends out these large solar storms and to be able to predict them during the sun's 11-year solar cycle. This event was particularly unusual because it happened during a very calm solar period.

"Observations of solar superstorms have been extremely lacking and limited, and our current understanding of solar superstorms is very poor," Liu said. "Questions fundamental to solar physics and space weather, such as how extreme events form and evolve and how severe it can be at the Earth, are not addressed because of the extreme lack of observations."

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Landsat 8 helps unveil the coldest place on Earth

Scientists recently recorded the lowest temperatures on Earth at a desolate and remote ice plateau in East Antarctica, trumping a record set in 1983 and uncovering a new puzzle about the ice-covered continent.

Ted Scambos, lead scientist at the National Snow and Ice Data Center (NSIDC), and his team found temperatures from -92 to -94 degrees Celsius (-134 to -137 degrees Fahrenheit) in a 1,000-kilometer long swath on the highest section of the East Antarctic ice divide.

The measurements were made between 2003 and 2013 by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on board NASA's Aqua satellite and during the 2013 Southern Hemisphere winter by Landsat 8, a new satellite launched early this year by NASA and the U.S. Geological Survey.

"I've never been in conditions that cold and I hope I never am," Scambos said. "I am told that every breath is painful and you have to be extremely careful not to freeze part of your throat or lungs when inhaling."

The record temperatures are several degrees colder than the previous record of -89.2 degrees Celsius (-128.6 degrees Fahrenheit) measured on July 21, 1983 at the Vostok Research Station in East Antarctica. They are far colder than the lowest recorded temperature in the United States, measured at -62 degrees Celsius (-79.6 degrees Fahrenheit) in Alaska, in northern Asia at -68 degrees Celsius (-90.4 degrees Fahrenheit), or even at the summit of the Greenland Ice Sheet at -75 degrees Celsius (-103 degrees Fahrenheit).

Scambos said the record temperatures were found in several 5 by 10 kilometer (3 by 6 mile) pockets where the topography forms small hollows of a few meters deep (2 to 4 meters, or 6 to 13 feet). These hollows are present just off the ice ridge that runs between Dome Argus and Dome Fuji -- the ice dome summits of the East Antarctic Ice Sheet. Antarctic bases sit on each of the sites and are generally not occupied during Antarctic winters.

Under clear winter skies in these areas, cold air forms near the snow surface. Because the cold air is denser than the air above it, it begins to move downhill. The air collects in the nearby hollows and chills still further, if conditions are favorable.

"The record-breaking conditions seem to happen when a wind pattern or an atmospheric pressure gradient tries to move the air back uphill, pushing against the air that was sliding down," Scambos said. "This allows the air in the low hollows to remain there longer and cool even further under the clear, extremely dry sky conditions," Scambos said. "When the cold air lingers in these pockets it reaches ultra-low temperatures."

"Any gardener knows that clear skies and dry air in spring or winter lead to the coldest temperatures at night," Scambos said. "The thing is, here in the United States and most of Canada, we don't get a night that lasts three or four or six months long for things to really chill down under extended clear sky conditions."

Centuries-old ice cracks

Scambos and his team spotted the record low temperatures while working on a related study on unusual cracks on East Antarctica's ice surface that he suspects are several hundred years old.

"The cracks are probably thermal cracks -- the temperature gets so low in winter that the upper layer of the snow actually shrinks to the point that the surface cracks in order to accommodate the cold and the reduction in volume," Scambos said. "That led us to wonder what the temperature range was. So, we started hunting for the coldest places using data from three satellite sensors."

More than 30 years of data from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA Polar Orbiting Environmental Satellite (POES) series gave Scambos a good perspective on what the pattern of low temperatures looked like across Antarctica.

"Landsat 8 is still a new sensor, but preliminary work shows its ability to map the cold pockets in detail," Scambos said. "It's showing how even small hummocks stick up through the cold air."

Scambos suspected they would find one area that got extremely cold. Instead they found a large strip at high altitude where several spots regularly reach record low temperatures. Furthermore, dozens of these extremely cold areas reached about the same minimum temperatures of -92 to -94 degrees Celsius (-134 to -137 degrees Fahrenheit) on most years.

"This is like saying that on the coldest day of the year a whole strip of land from International Falls, Minnesota to Duluth, Minnesota to Great Falls, Montana reached the exact same temperature, and more than once," Scambos said. "And that's a little odd."

A physical limit

The scientists suspect that a layer in the atmosphere above the ice plateau reaches a certain minimum temperature and is preventing the ice plateau's surface from getting any colder.

"There seems to be a physical limit to how cold it can get in this high plateau area and how much heat can escape," Scambos said. Although an extremely cold place, Antarctica's surface radiates heat or energy out into space, especially when the atmosphere is dry and free of clouds.

"The levels of carbon dioxide, nitrogen oxide, traces of water vapor and other gases in the air may impose a more or less uniform limit on how much heat can radiate from the surface," Scambos said.

Scambos and his team will continue to refine their map of Earth's coldest places using Landsat 8 data. "It's a remarkable satellite and we've repeatedly been impressed with how well it works, not just for mapping temperature but for mapping crops and forests and glaciers all over the world," Scambos said.

"The uses for Landsat 8 data are broad and diverse," said James Irons, Landsat 8 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "And Scambos' work is an example of some of the intriguing science that can be done using Landsat 8."

In the longer term, Scambos and his team will try to design weather stations and set them up in the area where the record temperatures occur to confirm the data from Landsat 8 and MODIS. Currently, most of the automated weather stations in the vicinity do not work properly in the dead of winter.

"The research bases there don't have people that stay through the winter to make temperature measurements," Scambos said. "We will need to investigate electronics that can survive those temperatures."

View the NASA animation The Coldest Place in the World: http://www.youtube.com/watch?v=Hp6wMUVb23c

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World temperature records available via Google Earth

Climate researchers at the University of East Anglia have made the world's temperature records available via Google Earth.

The Climatic Research Unit Temperature Version 4 (CRUTEM4) land-surface air temperature dataset is one of the most widely used records of the climate system.

The new Google Earth format allows users to scroll around the world, zoom in on 6,000 weather stations, and view monthly, seasonal and annual temperature data more easily than ever before.

Users can drill down to see some 20,000 graphs -- some of which show temperature records dating back to 1850.

The move is part of an ongoing effort to make data about past climate and climate change as accessible and transparent as possible.

Dr Tim Osborn from UEA's Climatic Research Unit said: "The beauty of using Google Earth is that you can instantly see where the weather stations are, zoom in on specific countries, and see station datasets much more clearly.

"The data itself comes from the latest CRUTEM4 figures, which have been freely available on our website and via the Met Office. But we wanted to make this key temperature dataset as interactive and user-friendly as possible."

The Google Earth interface shows how the globe has been split into 5? latitude and longitude grid boxes. The boxes are about 550km wide along the Equator, narrowing towards the North and South poles. This red and green checkerboard covers most of Earth and indicates areas of land where station data are available. Clicking on a grid box reveals the area's annual temperatures, as well as links to more detailed downloadable station data.

But while the new initiative does allow greater accessibility, the research team do expect to find errors.

Dr Osborn said: "This dataset combines monthly records from 6,000 weather stations around the world -- some of which date back more than 150 years. That's a lot of data, so we would expect to see a few errors. We very much encourage people to alert us to any records that seem unusual.

"There are some gaps in the grid -- this is because there are no weather stations in remote areas such as the Sahara. Users may also spot that the location of some weather stations is not exact. This is because the information we have about the latitude and longitude of each station is limited to 1 decimal place, so the station markers could be a few kilometres from the actual location.

"This isn't a problem scientifically because the temperature records do not depend on the precise location of each station. But it is something which will improve over time as more detailed location information becomes available."

This new initiative is described in a new research paper published on February 4 in the journal Earth System Science Data (Osborn T.J. and Jones P.D., 2014: The CRUTEM4 land-surface air temperature dataset: construction, previous versions and dissemination via Google Earth).

The CRUTEM4 data set is available from doi:10.5285/EECBA94F-62F9-4B7C-88D3-482F2C93C468.

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'Monster' sunspot could hurl flares at Earth

A "monster sunspot" more than 60,000 miles wide could send some powerful solar flares toward Earth on Wednesday, NASA says.

The sunspot -- actually a group of four spots, each larger than Earth, and smaller spots -- emerged over the weekend and was spotted by the orbiting Solar Dynamics Observatory and amateur astronomers, Spaceweather.com reported (via Space.com). It tossed off a moderately strong M-class flare today, and is expected to follow up with even stronger flares, possibly even X class.

Sunspot AR 1476 is so big that a photographer in the Philippines captured it at sunset, without a solar telescope.

But Spaceweather offers potential sungazers this crucial warning:

Even when the sun is dimmed by clouds and haze, looking into the glare can damage your eyes. Looking through unfiltered optics is even worse. If you chose to photograph the low sun, use the camera's LCD screen for viewfinding.

Sunspots don't excite you? How about a pair of coronal mass ejections, or a dark, coronal hole that has opened in the sun's atmosphere and is hurling solar winds toward us? Good chance of strong geomagnetic activity, including auroras.

Want to know the space weather now? NOAA has it.

The latest sun show comes three weeks after the spectacular eruption captured by the solar orbiter.

BLOG:  Satellite captures giant eruption from sun today

NASA has a primer on the solar cycle.

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Strong space weather storm hits Earth

The strongest space weather storm in five years struck Earth on Thursday, causing some airlines to reroute their flights, threatening power disruptions and sparking a show of the northern lights.

NASA and other agencies warned that the storm had the potential to disrupt global positioning systems, satellites and power grids, and had already caused some air carriers to change their planes' polar flight paths.

However, the Earth's magnetic field appeared to be absorbing the brunt of the shock and it was unlikely to reach the most severe levels, US experts said.

The leading edge of the coronal mass ejection -- a burst of hot plasma and charged particles -- that erupted from the Sun early Wednesday reached Earth on Thursday at 1045 GMT (5:45 am Eastern time in the United States), said an update from the National Oceanic and Atmospheric Administration (NOAA).

Predictions that the storm would reach a level three on a scale of five, or a "strong" level of solar radiation and geomagnetic storming, continue to "look justified," NOAA said.

"So far the orientation of the magnetic field has been opposite of what is needed to cause the strongest storming. As the event progresses, that field will continue to change."

NASA had forecast late Wednesday that the storm could reach "severe" levels, and its effects were expected to last through Friday.

The storm is likely "the strongest one since December 2006," NOAA scientist Joseph Kunches said on Wednesday.

Astronauts aboard the International Space Station were not expected to be affected by the radiation storm, NASA said.

A vivid display of the northern lights -- aurora borealis -- created when highly charged particles interact with the Earth's magnetic field, causing a colorful glow, was expected to be visible over central Asia at nightfall Thursday.

Geomagnetic and radiation storms are growing more frequent as the Sun leaves its solar minimum period and moves into a solar maximum over the coming years, but people are generally protected by Earth's magnetic field.

However, some experts are concerned that because the world is more reliant on GPS and satellite technology now than it was during the last solar maximum, more disruptions to modern life are likely.

The fuss began late Sunday at an active region on the Sun known as 1429, with a big solar flare that was associated with a coronal mass ejection that thrust toward the Earth at some four million miles per hour (6.4 million kilometers per hour).

A pair of solar flares and a CME followed overnight Tuesday-Wednesday, setting off a strong geomagnetic and solar radiation storm registering at level three on a five-step scale.

NASA said the first of the two flares on March 6-7 -- classified in the potent X class and facing directly at the Earth -- was the biggest this year and one of the largest of this cycle known as the solar minimum, which began in early 2007.

In fact, it was second only to a stronger one that erupted in August.

The solar flares alone caused brief high frequency radio blackouts that have already passed, according to NOAA.

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Why Early Earth Didn't Freeze Over Still a Mystery

Global warming gases cannot explain why Earth was not frozen billions of years ago when the sun was cooler, researchers say.

In the Archean Eon about 2.5 billion to 4 billion years ago, before the first advanced life appeared on the planet, the sun was only about 70 percent as bright as it is today. This means the amount of heat felt on Earth was much less, and Earth's surface should have been frozen.

However, ancient rocks at Isua near the southwest coast of Greenland indicate liquid water and even life was present on Earth about 3.8 billion years ago. "So Earth's climate had to be somewhere between the freezing point and boiling point of water, and probably pretty close to the temperature we have today, which sustains life," said researcher Emily Pope, an isotope geochemist at the Natural History Museum of Denmark in Copenhagen.

The contradiction between the cold Earth that apparently should have existed and the temperate Earth that apparently did exist is known as the "faint young sun paradox." Until now, the most popular explanation for this enigma was that there was a higher concentration of "greenhouse gases" such as carbon dioxide in the atmosphere than today. These gases absorb heat from the sun, helping warm the planet.

"Just like the average temperature of Earth is getting higher today because there are more greenhouse gases than there were before the Industrial Revolution, or even before the invention of agriculture, the presence of high concentrations of carbon dioxide and methane should have kept the early Earth warm," Pope said. [Early Earth Was Purple]

For greenhouse gases to explain the faint young sun paradox, their concentrations would need to have been extremely high, hundreds to thousands of times as much as today.

"If levels of carbon dioxide were that high, they would be recorded in ancient soils and sediments in the rock record," Pope said. "If levels of methane were that high, they would actually form a kind of organic haze in the atmosphere that blocks the sun's rays and would counteract its properties as a greenhouse gas."

Now scientists analyzing relatively pristine 3.8-billion-year-old rocks from Isua find no evidence that greenhouse gas levels were high enough to explain the faint young sun paradox, further deepening the mystery, Pope told LiveScience.

Specifically, researchers looked at serpentine mineral deposits, which form when ancient seawater interacts with deep ocean crust (the outer layer of Earth). These deposits record details of the water such as the hydrogen and oxygen isotope ratios found within, which rely in part on ocean size. Isotopes are atoms of the same element, like hydrogen, with differing numbers of neutrons. Light hydrogen isotopes are more likely to be found in the air and escape into space than heavier ones; the smaller the oceans, the more their waters will have slightly lower concentrations of light isotopes.

The rocks suggest that the oceans were up to 26 percent larger in the past. These shrunk over time to present-day volumes — seawater became trapped in newly formed continental rocks, and hydrogen that is one of the key ingredients of water instead escaped to outer space.

The rate of hydrogen loss to space is linked to atmospheric levels of methane and carbon dioxide; both these greenhouse gases can interact with hydrogen and other gases such as oxygen in complex ways. The hydrogen loss rate the researchers estimated based on these findings suggests that concentrations of these greenhouse gases were nowhere near high enough to reconcile the faint young sun paradox. [Stunning Images of the Sun]

"We have new concrete data that characterizes the early oceans," Pope said. "This will hugely help our ability to put realistic constraints on our models of how Earth's oceans and atmosphere first evolved."

An alternative explanation for the faint young sun paradox is that early in Earth history, there were fewer continents because a number had not formed yet; less land mass would have meant less cloud cover, because there weren't biologically generated particles such as pollen and spores that could behave as seeds around which the clouds could form. 

"The result was that the planet, covered mostly by oceans, was darker, and like an asphalt road on a hot day, could absorb a lot more heat, enough to keep the Earth clement," Pope told LiveScience.

The scientists detailed their findings online March 5 in the journal Proceedings of the National Academy of Sciences.

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Sun hurls strong geomagnetic storm toward Earth (Reuters)

WASHINGTON (Reuters) – The strongest geomagnetic storm in more than six years was forecast to hit Earth's magnetic field on Tuesday, and it could affect airline routes, power grids and satellites, the U.S. Space Weather Prediction Center said.

A coronal mass ejection - a big chunk of the Sun's atmosphere - was hurled toward Earth on Sunday, driving energized solar particles at about 5 million miles an hour (2,000 km per second), about five times faster than solar particles normally travel, the center's Terry Onsager said.

"When it hits us, it's like a big battering ram that pushes into Earth's magnetic field," Onsager said from Boulder, Colorado. "That energy causes Earth's magnetic field to fluctuate."

This energy can interfere with high frequency radio communications used by airlines to navigate close to the North Pole in flights between North America, Europe and Asia, so some routes may need to be shifted, Onsager said.

It could also affect power grids and satellite operations, the center said in a statement. Astronauts aboard the International Space Station may be advised to shield themselves in specific parts of the spacecraft to avoid a heightened dose of solar radiation, Onsager said.

The space weather center said the geomagnetic storm's intensity would probably be moderate or strong, levels two and three on a five-level scale, five being the most extreme.

(Reporting By Deborah Zabarenko, Environment Correspondent; Editing by Mohammad Zargham)

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Power companies prepare as solar storms set to hit Earth (Reuters)

NEW YORK (Reuters) – Three large explosions from the Sun over the past few days have prompted U.S. government scientists to caution users of satellite, telecommunications and electric equipment to prepare for possible disruptions over the next few days.

"The magnetic storm that is soon to develop probably will be in the moderate to strong level," said Joseph Kunches, a space weather scientist at the Space Weather Prediction Center, a division of the U.S. National Oceanic and Atmospheric Administration (NOAA).

He said solar storms this week could affect communications and global positioning system (GPS) satellites and might even produce an aurora visible as far south as Minnesota and Wisconsin.

An aurora, called aurora borealis or the northern lights in northern latitudes, is a natural light display in the sky in the Arctic and Antarctic regions caused by the collision of energetic charged particles with atoms in the high altitude atmosphere.

Major disruptions from solar activity are rare but have had serious impacts in the past.

In 1989, a solar storm took down the power grid in Quebec, Canada, leaving about six million people without power for several hours.

The largest solar storm ever recorded was in 1859 when communications infrastructure was limited to telegraphs.

The 1859 solar storm hit telegraph offices around the world and caused a giant aurora visible as far south as the Caribbean Islands.

Some telegraph operators reported electric shocks. Papers caught fire. And many telegraph systems continued to send and receive signals even after operators disconnected batteries, NOAA said on its website.

A storm of similar magnitude today could cause up to $2 trillion in damage globally, according to a 2008 report by the National Research Council.

"I don't think this week's solar storms will be anywhere near that. This will be a two or three out of five on the NOAA Space Weather Scale," said Kunches.

SOLAR SCALE

The NOAA Space Weather Scale measures the intensity of a solar storm from one being the lowest intensity to five being the highest, similar to scales that measure the severity of hurricanes, tornadoes and earthquakes.

The first of the three solar explosions from the sun this week already passed the Earth on Thursday with little impact, Kunches said, noting, the second was passing the Earth now and "seems to be stronger."

And the third, he said, "We'll have to see what happens over the next few days. It could exacerbate the disturbance in the Earth's magnetic field caused by the second (storm) or do nothing at all."

Power grid managers receive alerts from the Space Weather Prediction Center to tell them to prepare for solar events, which peak about every 12 years, Tom Bogdan, director of the center said.

He said the next peak, called a solar maximum, was expected in 2013.

"We're coming up to the next solar maximum, so we expect to see more of these storms coming from the sun over the next three to five years," Bogdan said.

(Reporting by Scott DiSavino; Editing by Alden Bentley)

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On Fourth of July, Earth Is Farthest from the Sun (SPACE.com)

The weather forecast for this year's Fourth of July holiday in the United States calls for high temperatures across much of the country's central and southern states, with some places expected to surpass 100 degrees for the American holiday. So it may come as a surprise that despite this heat, the planet is actually about as far away from the sun as it ever gets.

At about 11 a.m. EDT (1500 GMT) on the Fourth of July, the Earth will reach that point in its orbit where it is farthest from the sun. Called aphelion, this location in Earth's orbit puts the planet about 94.5 million miles (152 million kilometers) from the sun. That's about 3.1 million miles (4.9 million km) more than the Earth's closest distance to the sun (called perihelion), which occurred on Jan. 3. 

The exact difference in the distance between Earth's closest and farthest points from the sun is 3,104,641 miles (4 996 435 km), or 3.28 percent, which makes a difference in radiant heat received by the planet of nearly 7 percent. The average distance between the Earth and sun is about 93 million miles (150 million km). [10 Extreme Planet Facts]

Closer doesn't necessarily mean hotter

If you ask most people in the Northern Hemisphere which month of the year they think the Earth is closest to the sun, they may likely say it happens in June, July or August, some of the hottest months of the year.  

But our warm weather doesn’t relate to our distance from the sun. It's because of the 23.5-degree tilt of the Earth's axis that the sun is above the horizon for different lengths of time at different seasons. The tilt determines whether the sun's rays strike us at a low angle or more directly. 

At New York's latitude, the more nearly direct rays at the summer solstice of June 21 bring about three times as much heat as the more slanting rays at the winter solstice on Dec. 21. Heat received by any region is dependent on the length of daylight and the angle of the sun above the horizon.

So there are noticeable differences in temperatures that are registered over different parts of the world, including the Southern Hemisphere, where it is winter right now.

A climate fallacy

When I attended Henry Bruckner Junior High School in The Bronx, my earth science teacher, Mr. Shenberg, told all of us that because Earth is farthest from the sun in July and closest in December, that such a difference would tend to warm the winters and cool the summers … at least in the Northern Hemisphere. 

And yet the truth of the matter is that the preponderance of large land masses in the Northern Hemisphere works the other way, and actually tends to make the winters colder and the summers hotter.   

Interestingly, the times when the Earth lies at its closest and farthest points from the sun roughly coincide with two significant holidays. When Earth is closest to the sun around New Year's Day and farthest from the sun around Independence Day.

Depending on the year, the date of perihelion can vary from Jan. 1 to 5, while the date of aphelion can vary from July 2 to July 6.

So while you're out in the Fourth of July sun this holiday, take a moment to appreciate the celestial dance the Earth is making at the exact same time and enjoy the sunshine.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y.

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