STORMS FROM THE SUN

For Florence, a shelter from this storm

For Nancy and Ramon III, children of the space weather generation

Every day the rising and setting of the Sun regulate the lives of some 6 billion persons and a vastly greater number of other living creatures on the Earth. Indeed, “sunshine” is responsible for the long-term development and maintenance of the entire biosphere in all of its wondrous complexity and diversity. Not a bad performance for the quiescent thermal radiation of 1.36 kilowatts per square meter from a ball of gas at an effective temperature of 5,770 degrees Kelvin and a distance of 150 million kilometers!

And that is only the “first approximation,” as scientists say, to the Sun’s influence on the Earth.

The second approximation, now called space weather, encompasses a body of lesser phenomena most of which are not discernible to the unaided human senses and were therefore unknown to pretechnological peoples. The notable exceptions are the luminous visual displays in the Earth’s upper atmosphere, termed the aurora borealis and the aurora australis.

This well-written and splendidly illustrated book by Michael J. Carlowicz and Ramon E. Lopez provides a timely and broadly

intelligible overview of the nature of space weather. It is replete with historical background, anecdotal examples and citations of the recent contributions of many individuals. Above all, it is instructive for everyone who has an interest in the rapidly evolving science of space weather and its multifold implications in our technological culture.

The foundations of the subject have been under slow but progressive development for centuries but, until recently, have been of professional interest to only a small cadre of investigators who publish their findings in highly technical journals and specialized monographs. The 1957-1958 International Geophysical Year launched a major increase in worldwide scientific work in space physics. This increase has been sustained and accelerated in subsequent years.

In brief, space weather is attributable to the highly variable, outward flow of hot ionized gas (a weakly magnetized “plasma” at a temperature of about 100,000 degrees Kelvin, called the solar wind) from the Sun’s upper atmosphere and to nonthermal, sporadic solar emissions of high-energy electrons and ions and electromagnetic waves in the X-ray and radio portions of the spectrum. There are also significant contributions by the relatively constant bombardment of the Earth by cosmic rays from distant sources in the galaxy. The power flow of each of these causes of space weather is far less than the previously quoted power flow of thermal radiation.

One of the early (1936) practical applications of space weather was the daily publication of maximum usable frequencies for shortwave radio communication by the U.S. National Bureau of Standards and by corresponding agencies in other countries. These advisories rested on routine observations of the partially ionized layers of the Earth’s upper atmosphere, called the ionosphere.

The current and prospective importance of space weather in the realm of practical matters is attributable to the rapid advances that are being made in sophisticated applications of modern technology, both civil and military. Such applications include global telecommunications, large arrays of electrical power grids, navigation,

reconnaissance and surveillance, forecasts of ordinary weather, safety of human space flight, and reliability and failure modes of hundreds of satellites of the Earth which serve these functions.

Despite voluminous scientific knowledge of the physics of magnetic storms and the sporadic emission of solar energetic particles, there is now a clear need for the application of this knowledge to informative and reliable forecasts. It is of central importance that forecasters work closely with engineers of vulnerable systems in order to reduce hyperbolic rhetoric and false alarms and to develop a mature and reliable body of forecasts that practitioners can take seriously. Improved knowledge of the fundamentals of space weather continues to be a largely governmental function, as is the case with ordinary weather, but it is now clear that increased commercial attention to alleviating the hazards of space weather is timely and appropriate. To this end, operators of electrical power grids and hundreds of Earth satellites and interplanetary spacecraft may well take this book to be a wake-up call for the design and development of invulnerability to adverse effects of space weather. Such engineering responses include identification and replacement of susceptible elements and the development of operational protocols, automatic self-checking and self-correcting circuits, and work-around software. Such measures are now made feasible by the very sophistication that has made modern space techniques of importance to our daily activities.

I commend this book to a wide spectrum of readers who may join me in enjoying a compelling account of the fascinating field of space weather and its evolving effects on our daily lives.

STORMS FROM THE SUN