© Royal Swedish Academy of ScienceThe sun's warning signs
The sun sometimes hurls clouds of plasma our way, which can fry satellites and knock out power grids on Earth. The outbursts are most common during solar maxima, when the dark blemishes of sunspots appear in greatest abundance on the sun.
Although there is an average of 11 years between solar maxima, predicting the exact timing and height of each peak is difficult as there is little historical data to plug into models. About two dozen solar cycles have occurred since reasonably complete records began. Now an analysis of historic sunspot drawings suggests that this patchy record had omitted a solar cycle from the late 1700s.
Sunspot numbers for this period were compiled by Swiss astronomer Rudolf Wolf in the 19th century, who based his tallies on drawings of the sun made by Austrian amateur astronomer Johann Staudecher. Wolf's numbers suggested there was a 15.5-year-long solar cycle between 1784 and 1799, the longest on record. However, astronomers have long questioned the reliability of these numbers, since Staudecher's observations from this period are sparse - he made just two drawings in the second half of 1793, for example. Even in the 19th century, some suspected that it might have actually been two short solar cycles.
Comment: These are possibilities, of course. One may want to consider this as well: Military Hush-Up: Incoming Space Rocks Now Classified