Contrasting Large Solar Events

Abstract

After an unusually long solar minimum, solar cycle 24 is slowly beginning. A large coronal mass ejection (CME) from sunspot 1092 occurred on 1 August 2010, with effects reaching Earth on 3 August and 4 August, nearly 38 years to the day after the huge solar event of 4 August 1972. The prior event, which those of us engaged in space research at the time remember well, recorded some of the highest intensities of solar particles and rapid changes of the geomagnetic field measured to date. What can we learn from the comparisons of these two events, other than their essentially coincident dates? One lesson I took away from reading press coverage and Web reports of the August 2010 event is that the scientific community and the press are much more aware than they were nearly 4 decades ago that solar events can wreak havoc on space-based technologies. This is probably because there were fewer technologies under potential assault by the 1972 event. Back then, systems at risk included long conductors that facilitated power grids and communications cables, radio frequency (RF) communications, and largely transistor-based electronics on flying spacecraft. Today the technologies that can be affected are greatly expanded in type and include communications by wireless devices, high-density integrated circuits and memory chips, satellite-to-ground communications and entertainment, navigation by the Global Positioning System, and longer and more interconnected (and therefore potentially more vulnerable) electric power grids. Effects from the 1972 event included dramatic decreases in spacecraft solar array outputs and a long outage in Plano, Ill., of an AT&T communications cable transmitting voice from Chicago to San Francisco. From a research perspective, the event at Earth occurred with an interplanetary magnetic field nearly in the equatorial plane or even slightly positive. No magnetosphere ring current developed; the large, rapid changes in the dayside geomagnetic field resulted from a severe compression of the magnetosphere. These factors are all quite different from present-day modeling of disturbances at Earth following large solar events. Few impacts—and certainly no dramatic ones—on technologies resulted from the August 2010 event, despite several predictions to the contrary. Thus, another lesson I took from the 2010 event is that the space research community must be careful in how it presents its results and speaks about space weather and its effects on society. The research community must caution amateurs, the press, and the public that there remains very much we still do not know about the coupling of a single event seen on the Sun to Earth's space environment. While the increase over the past 40 years in public awareness of space weather is very positive, and the World Wide Web is a wonderful tool for enhancing this awareness, there can be a tendency—by both researchers and the press who speak to them—to overhype the potentially deleterious effects of a particular event. Let us all be vigilant about how we present our research and our understandings. Louis J. Lanzerotti is editor of Space Weather and a distinguished research professor at the New Jersey Institute of Technology, in Newark.