Note to Editors: Contents embargoed until 1:45 p.m. EST on Sunday, Feb 20.
Massive solar storms that hammered Earth's space environment in fall 2003 and turned a normally safe region for satellites into a hazardous zone of energetic particles may not be as cyclic as once believed, according to a University of Colorado at 麻豆影院 professor.
Daniel Baker, director of CU-麻豆影院's Laboratory for Atmospheric and Space Physics, said the "Halloween Storms" of 2003 and similar events during summer 2004, and even events during the past few weeks, are evidence that solar storms are not tightly tied to peaks in the 11-year-long solar cycles. Most solar physicists contend that the present solar cycle peaked in 2000 or 2001.
"The sun has been throwing some unexpected curves at us," he said. "The message here is that the sun can be very active during broad periods, and that we can expect frequent, irregular activity over a large part of its 11-year sunspot cycle."
Baker will give a presentation on the subject at the annual American Association for the Advancement of Science Meeting Feb. 17 to Feb. 21 in Washington, D.C. Baker is participating in a symposium at the meeting on Feb. 20 titled "The Greatest Solar Storms."
The Halloween solar storms of October and November 2003 were marked by highly energetic particles emanating from the sun, as well as the acceleration of particles near Earth in a zone between two donut-shaped bands of radiation girdling the planet known as the Van Allen Belts, he said.
The normally quiescent region, which ranges from about 4,000 miles to 8,000 miles above Earth, was previously considered to be a "safe zone" for satellites and immune from substantial amounts of radiation, said Baker.
During the Halloween storms, coronal mass ejections from the sun hurled electrified gas clouds weighing billions of tons into Earth's magnetic field at several million miles per hour, he said. The radiation made the safe zone between the Van Allen Belts thousands of times hotter and more energetic and hazardous to spacecraft, said Baker, an internationally known space weather expert.
The hopped-up electrons inside the zone and the energetic protons emanating from the sun disrupted an estimated 60 percent of operational near-Earth satellites, he said. The powerful solar events also temporarily increased the volume of the solar system, or heliosphere, by 30 percent about eight months after the storms reached Earth. The storm effects were observed by spacecraft monitoring Mars, Jupiter and Saturn, said Baker.
Extreme space weather cropped up again over Earth when several solar storms pummeled Earth's magnetosphere in July 2004, said Baker. "The space environment has remained hot now for several years, and we just had a very powerful set of solar storms in January 2005," he said. "We can't afford to let our guard down when operating spacecraft in the near-Earth environment."
Scientists are particularly concerned about the disruption of signals from a constellation of 24 Global Positioning System satellites, which orbit at roughly 10,000 miles above Earth and are regularly used to track the position of aircraft within inches as they move about the skies, he said. The Halloween storms caused a temporary disruption of airline navigation systems by scrambling GPS communications, causing anxious moments for air traffic controllers, Baker said.
Scientists have come a long way in understanding the physics of space weather since 1859, when a solar storm known as the "Carrington Event" slammed into Earth's environment, he said. The famous event disrupted telegraph communications worldwide and even allowed New England residents to read newspapers by the light of Earth's supercharged aurora.
"We are more dependent than ever on technology, and therefore more susceptible to the effects of space weather," Baker said. "But scientists and engineers have made great strides in recent decades regarding this phenomenon. We understand much more about what is happening and can build more robust systems to withstand the effects."