Caption: 
To reconstruct the Sun’s polar magnetic behavior over more than 100 years, an SwRI scientist first corrected anomalies in historical data from Kodaikanal Solar Observatory (KoSO) to sync with direct modern measurements of the Sun’s poles. Comparing observations from KoSO in Calcium-K light with magnetic field measurements from the Solar and Heliospheric Observatory’s Michelson Doppler Imager (left) highlights the association of bright regions in Ca K with magnetic activity in the Sun. The right image shows dark blue and green (north polarity) yellow and orange regions (south polarity) regions, indicating where Ca K light and magnetic data are highly correlated.