Preserving a 45-Year Record of Sunspots:

In 1964, the late solar researcher Patrick McIntosh launched an ambitious effort to track sunspots -- relatively cool, dark blotches on the Sun caused by disturbances in the star's magnetic field. He traced sunspots and other solar surface features from daily photographs, creating a map of the full Sun approximately every 27 days. This led to important advances in the prediction of solar flares and helped to reveal the large-scale organization of the Sun's magnetic field. Now scientists are working to preserve and digitize McIntosh's project, a uniquely consistent record of solar activity over 45 years. The Sun's magnetic field is driven by the interior flow of hot plasma, or electrified gas, which creates a magnetic generator called a dynamo. McIntosh's records showed that the location and number of sunspots and filaments -- huge arcs of dense plasma that appear as dark lines on the Sun's surface -- are indicators of just how this dynamo works. By carefully documenting the position and number of sunspots over time, for example, McIntosh's record illustrated how the Sun's entire magnetic field flips polarity every 11 years. The number of visible sunspots helps researchers predict this flip: When the Sun emits more X-ray and ultraviolet radiation, a period called the solar maximum, the number of sunspots peaks. When solar activity dwindles during the solar minimum, sunspots dwindle. McIntosh's maps were unique for also tracking the position of filaments and other features that also change as the magnetic field evolves, drifting poleward or toward the Sun's equator at different stages of the solar cycle.

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