Solar weather: how it could mess up our cable TV
Wouldn´t this mess up other means of communications we have?
We don't think much about the weather in space until it threatens to interrupt our TV viewing, as it is doing this month.
A solar storm that followed a mass coronal ejection on the sun's surface is blamed for knocking a communications satellite off its orbit in early April.
Intelstat, operator of the Galaxy-5 communications satellite, told The Associated Press that it probably can avoid interfering with a satellite that transmits cable-television signals when the two pass close by later this month, but solar astronomers warn that incidents such as this one could recur in the near future.
The sun is emerging from a prolonged quiet period, during which time we have become increasingly dependent on space satellites for all our communications.
Years of observing sunspots, those cool areas on the sun's surface that often precede the flare-ups known as coronal mass ejections, established a regular rhythm to the sun's activity. Every 11 years or so, the sun changes polarity, and each cycle has a peak and a minimum of activity.
The last peak occurred in 2000-02, and the next is now predicted for as late as 2013 or 2014, said Matt Penn, telescope scientist for the National Solar Observatory's McMath-Pierce telescope on Southern Arizona's Kitt Peak.
"The evidence is pretty convincing that we've gone through the minimum," Penn said.
That doesn't mean the 24th Solar Cycle will be disruptive, Penn said. "In the long term at McMath, we have seen the sunspots seem to be getting weaker. Half my colleagues don't buy it, but that would suggest it would have less activity."
Catastrophic events can happen, though, even in less active times, he said.
The strongest geomagnetic event in the historical record, the Carrington Storm of 1859, occurred during a relatively quiet period in the sun's activity, Penn said.
A lot depends on the direction of the ejections, which occur regularly, even during quiet periods. The magnetic field of the Carrington Storm was directly opposed to the Earth when it was released from the sun. That storm pushed sightings of the aurora borealis as far south as Cuba, and it interrupted the nation's telegraph system. If such a storm hit today, Penn said, it would knock every satellite we have out of orbit.
On the ground, it would knock out electrical and transportation systems. A report by the National Academy of Sciences concluded it would take 10 years to recover from the $1 trillion to $2 trillion in damage such a storm would cause.
Frank Hill, director of the Global Oscillation Network Group solar seismology project at the National Solar Observatory, said his favorite story about the Carrington event is that it caused fires in telegraph offices by sending increased currents along telegraph lines.
Hill said solar flares and mass coronal ejections will "be on the increase over the next five years." A lot is at risk on Earth and in orbit, he said.
In addition to satellites and communications, "GPS systems are also sensitive to charged particles from the sun that set up disturbances in the ionosphere," Hill said.
You won't notice it in your automobile's mapping system, Hill said, but it could wreak havoc with more sensitive measurements for airplane landings and things such as "drilling in the Gulf of Mexico."
Solar astronomers would like to better understand the sun's mechanisms. Right now, through observations of the sunspots and the movement beneath them, they can, at best, give two to three days' notice of coronal mass ejections.
"I think that understanding the impact the sun has on our day-to-day lives is going to be more important in the future," Penn said.
New tools are on the way to understand the sun and aid in prediction of space weather.
NASA's Solar Dynamics Observatory is positioned to record a high-resolution movie of the entire 24th Solar Cycle. The National Solar Observatory is building the world's largest solar telescope on a peak on the Hawaiian island of Maui.
For now, the sun remains a big, complex, imperfectly understood place whose effect on the Earth is sometimes hard to measure, said Joe Giacalone, who studies charged particles accelerated by solar storms at the University of Arizona's Lunar and Planetary Laboratory.
"You have to be very perceptive to see changes caused in the Earth by the sun," Giacalone said, "but now the technology notices."