The purpose of this paper is to introduce the reader to the active sun as a source of disturbance that affect the magnetic field measured at the earth's surface. Included under this topic are the general sun's properties, solar surface activity centers and characteristics of the solar field and ejecta flowing into interplanetary space.

This report is an introduction to solar-terrestrial phenomena for those with no special background in astrophysics or solar astronomy. Discussions of physics have been kept to a minimum, with emphasis on phenomonology instead. An individual completely unfamiliar with solar events should, after reading this volume, be able to read and understand the SESC Report and Forecast of Solar Geophysical Activity and be able to apply its contents to his particular area of concern. This volume is also intended as a quick reference work for Skylab ATM Principal Investigator Teams to assist them in using the ATM data book. For that reason, a list of abbreviations used in forecasts and observatory reports is included. Subjects discussed are solar structure and processes, solar activity, and solar-terrestrial relations. There is a brief description of the Space Environment Services Center's activities.

This books presents a brief review of modern concepts of the Sun-Earth problem and proposed physical mechanisms of solar-terrestrial relations (STR). This field covers a wide range of fundamental and actual applied problems of paramount importance (Space Weather, radiation hazard in space, functioning of space-borne and ground-based technological systems, heliobiology etc.). It is also closely tied with some general gnosiological problems. The author provides state-of-the-art information about existing problems and discusses different channels for extraterrestrial influences at the up-to-date level: electromagnetic waves and fields, total solar irradiance, solar wind, energetic solar particles, galactic cosmic rays, cosmic dust, etc. Some of the well-known and suggested STR effects and corresponding physical mechanisms are illustrated by several examples. In particular, a number of different external “signals” in observed changes of terrestrial climate and weather are considered. Especially, an expected impact of geophysical disturbances on the accuracy of some precise physical measurements and experiments is analysed. Due attention is paid to the heliobiological aspects of STR. Particular emphasis is on the multifactor nature of magneto-biological effect (MBE), its non-stationary and non-linear behaviour. The author also discusses main features of different physical mechanisms (electromagnetic fields, ionising radiation, triggers, rhythmic and resonances in solar-terrestrial systems) and their applicability to the Sun-Earth problem. The most of them are still needed in more sophisticated theoretical development and experimental confirmation. The main goals of interdisciplinary studies in this field are to determine partial impacts of solar-geomagnetic variability on the terrestrial environments and estimate (separate) relative contributions of different factors into various STR phenomena. The book is based on lectures given on advanced undergraduate level and will also benefit newcomers (physicists and engineers) to the field.