New Forecast: Sun's 'Superstorms' Could Doom Satellites (SPACE.com)

Magnetic storms set off by the sun could pose a bigger threat than thought to weather, communication, military and other satellites close to Earth, with a potentially devastating economic impact, scientists suggest.

In the new study, researchers found that solar radiation can energize a belt of high-energy particles that surrounds Earth more dramatically than previously believed.

The study focused on the possible effects of a particularly strong magnetic storm on the Van Allen radiation belts, the dangerous rings of high-energy particles that girdle the Earth. The belts are split into two distinct zones. The outer belt, which is made up of electrons, reaches from about 15,800 to 31,600 miles (25,500 to 51,000 kilometers) above the surface, while the inner belt, which consists of a mix of electrons and protons, reaches from about 4,000 to 8,000 miles (6,400 to 12,800 km) above. [Stunning Photos of Solar Flares & Sun Storms]

Scientists had known the outer belt could become far more intense during geomagnetic storms caused by high-energy particles spewed by the sun, such as the storm that supercharged Earth's northern lights display Monday night (Sept. 26). However, they have long thought such storms do not affect the inner belt.

Now computer simulations suggest that during a "superstorm" — which has occurred in the past and is likely to recur in the future ? the electrons in the inner belt, too, could become energized. Near-Earth radiation could then remain dramatically more intense for several years afterward.

"The increase in radiation in the inner zone may last for up to a decade and continue damaging satellites for years after a very strong storm," study lead author Yuri Shprits, a space physicist at the University of California, Los Angeles, told SPACE.com.

This radiation would damage satellites in that zone and potentially cut their lifetimes by five-sixths or more. [Related: Space Radiation to Rise for Astronauts, Airline Passengers]

"It would not destroy all satellites at once," Shprits said. "However, at least according to our calculations, a very strong storm can increase the radiation dose in the inner zone by a factor of 10, and within a few years we may lose a significant portion of the satellites that traverse the inner zone."

In terms of new strategies that might be needed to protect satellite systems, "it's hard to say," Shprits said. "First of all, we need to estimate risks and estimate cost. If cost is too high, we may want to accept the risks and start getting ready to replenish the fleet in the case of such event."

"There are a number of rather expensive strategies that can be used to mitigate the risk, including redundancy in electronics and increased shielding," he added. "Zero risk means infinite cost."

Two missions to study the radiation belts are planned for 2012, Shprits noted: NASA's Radiation Belt Storm Probe will observe radiation belts in the equatorial plane, while Moscow State University's LOMONOSOV mission, with UCLA-built instruments on board, will observe radiation belts at low altitudes.

The scientists detailed their findings online in the Aug. 25 issue of the journal Space Weather.

Follow SPACE.com contributor Charles Q. Choi on Twitter @cqchoi. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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Hurricane Irene Spotted From Space (SPACE.com)

Hurricane Irene, the first hurricane of the 2011 Atlantic hurricane season, was seen from space today (Aug. 22) as it roared past Puerto Rico.

Irene formed as a tropical storm east of the Leeward Islands on Aug. 20. By early Aug. 22, the storm had strengthened to a Category 1 hurricane. The U.S. National Hurricane Center (NHC) reported that Irene had maximum sustained winds of 80 mph (130 kph), with higher gusts. The storm was located about 150 miles (240 kilometers) west-northwest of San Juan, Puerto Rico.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image at 11:20 a.m. local time (15:20 UTC) on Aug. 22. Storm clouds cover part of the Dominican Republic, and all of Puerto Rico. [See satellite photos of Hurricane Irene]

As of Aug. 22, Irene had cut power to more than a million residents of Puerto Rico, according to ABC News. The Miami Herald reported that heavy rains had pushed at least five rivers over their banks on the island. Citing continuing rains, downed power lines, and potential landslides, the Puerto Rico governor urged residents to stay indoors.

Moving westward to the island of Hispaniola, Irene menaced the Dominican Republic and Haiti. The storm’s worst winds and rains remained north of the island, reducing the threat of deadly flooding, according to news reports. Nevertheless, authorities worried about approximately 600,000 Haitians still living in Port Au Prince tent cities after the 2010 earthquake. [Weirdo Weather: 7 Weird Weather Events]

The NHC reported that a hurricane warning was in effect for the north coast of the Dominican Republic, the southeastern Bahamas, and the Turks and Caicos Islands. A hurricane watch was in effect for the north coast of Haiti. Irene was moving toward the west-northwest at roughly 12 mph (19 kph), and was expected to continue in that direction for the next day or two.

Five-day projections released by the NHC on Aug. 22 showed Irene heading for the continental United States, potentially making landfall in Florida, Georgia or the Carolinas.

Irene is the first hurricane for what has been forecast to be an active season. The National Oceanic and Atmospheric Administration (NOAA) updated its forecast on Aug. 4, predicting 14 to 19 named storms (which include tropical storms and hurricanes), seven to 10 hurricanes and three to five major hurricanes (Category 3 or higher). An average Atlantic hurricane season will see 11 named storms, six hurricanes and two major hurricanes. August through October are the peak months of the Atlantic hurricane season.

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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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