Int. J. Environ. Res. Public Health 2010, 7 941 explaining why this particular EM force puts in motion and governs biological processes, implementing signaling and regulatory functions in every living creature and in the whole Biosphere. This concept has been convincingly substantiated in the current literature [19,22-25]. It is important to note that the main part of the known solar regulatory signals influencing Biosphere are of electromagnetic nature: - in most evident cases it is solar light, which represent electromagnetic waves of definite wavelength, and has numerous biological effects, including regulation of circadian rhythms in living beings. - in the case of cycles of Solar activity it is alterations of the Earth’s Magnetic field, caused by fluctuations in levels of solar ionizing radiations and solar energy output (Figure 1). - it is also worthy to mention a slowly-varying Microwave emission from the solar corona. Figure 1. Periodicities in solar and geomagnetic activity. The left panels show time series of the monthly values of the sunspot number and the geomagnetic Ap index. The top right panel shows the solar cycle variation present both in the geomagnetic and solar records, showing peak geomagnetic activity during the declining phase of the solar cycle. The bottom right panel shows the semiannual variation in the geomagnetic data not visible in the solar records. (From [26], reproduced by the kind permission of the author and the publisher. The source database: [27]). 3. Theoretical Possibility and Evidences of Bio-Regulatory Effects of Weak Magnetic Fields Recent genetic studies of different cell lines and primary cells provide convincing evidence of the bio-regulatory capabilities of magnetic and electromagnetic fields. Distinct changes in gene expression