"The sun is approaching the height of its 11-year storm cycle ..." 5-5-2000? Scientists Warn of Solar Storm By JOSEPH B. VERRENGIA .c The Associated Press BOULDER, Colo. (AP) - Scientists detected a major solar flare Friday that could create a spectacular light show in the night sky but was not expected to disrupt communications or knock out electrical power. The National Oceanic and Atmospheric Administration's forecast of moderate solar storm activity was in effect through midday Saturday EDT. While geomagnetic eruptions on the sun can interfere with communications and knock out power, no immediate disruptions were reported. Forecasters said the intense part of the storm had passed by midday Friday, but there was a chance of another outbreak on Sunday. The sun is approaching the height of its 11-year storm cycle, known as the Solar Max, although the peak had been relatively quiet until now. The storm was rated at a moderate G-2 level on the federal government's new space weather scale of 1 to 5. Initially, the storm spiked to G-4, or severe. Scientists said the storm originated Tuesday morning when a cluster of sunspots emerged, then faded, on the sun. A cloud of electrically charged particles hurled from the sun rode the solar wind and reached Earth's magnetic field midday Thursday. Eric Ort, a space weather forecaster, said he received reports from Ireland that the display of the aurora borealis, or northern lights, was spectacular as a result of the solar storm. Weather permitting, the display might be visible at lower latitudes after midnight for the next night or two, he said. The Space Weather Operations Center is jointly operated by NOAA and the Air Force. On the Net: www.noaa.gov Solar shock waves can spawn blasts from sun report WASHINGTON, April 4 (Reuters) - In a sort of remote-control effect, shock waves on one part of the sun can spawn monster explosions in other solar regions, which sometimes damage power grids and satellites around Earth, scientists said on Tuesday. Earlier research indicated that these big explosions, known as coronal mass ejections, were fuelled by solar flares directly underneath them. But new observations indicate the massive blasts can occur far from the solar flares that spark them. These ejections are a prime ingredient in geomagnetic storms, which can cause bright auroras, damage satellites in Earth orbit and disrupt power by generating strong electric currents under Earth's surface. The remote-control ejections appear to emanate from very large hot loops of X-rays which seem to connect sunspots in the sun's northern and southern hemispheres, scientists Josef Khan and Hugh Hudson wrote in the April 15 edition of Geophysical Research Letters. Using Japan's Yohkoh (''sunbeam'') satellite, the two researchers looked at X-ray images of the sun and found that three of these big X-ray loops simply disappeared, violently freeing huge amounts of solar material. These loopy ejections were tracked far out into the sun's corona -- a wildly-shaped halo of electrified gas -- with NASA's Solar and Heliospheric Observatory (SOHO) satellite. Khan and Hudson theorise that some coronal mass ejections are caused when a solar flare generates a shock wave, and that wave crosses a large X-ray loop. This makes the loop unstable and causes it to erupt, ejecting hot X-ray material that becomes a large part of the coronal mass ejection. While both researchers are currently based at Japan's Institute of Space and Astronautical Science, Khan is with University College, London, and Hudson is with the Solar Physics Research Corporation in Tucson, Arizona.
