January 20, 2026 — Research conducted by an international team of astronomers from Southwest Research Institute, Aryabhatta Research Institute of Observational Sciences in India and the Max Plank Institute in Germany could help predict upcoming solar cycle activity. To enable these predictions, the team devised a new way to look at historical data from the Kodaikanal Solar Observatory (KoSO), a field station of the Indian Institute of Astrophysics (IIA) Bangalore, to reconstruct the Sun’s polar magnetic behavior over more than 100 years.
“We needed to find the polar magnetic information hidden in the historical data,” said SwRI scientist Dr. Bibhuti Kumar Jha, second author of a paper about these findings in the Astrophysical Journal. “To start, we cleaned up and calibrated early data to today’s standards and then correlated patterns with modern observations. I addressed anomalies like time zone slips and rotation errors to enable this kind of study.”
The rhythms of solar activity across its approximately 11-year cycle have left scientists puzzled for more than a century. Understanding the patterns of sunspots, solar flares and magnetic storms is crucial to protecting satellites and other Earth technology from space weather events. The Sun’s polar magnetic field is pivotal to understanding solar processes to forecast future solar cycles, but the first direct measurements of the polar field only started in the 1970s. Calcium K (Ca II K) observations capture the Sun’s chromosphere, revealing its magnetic fields and activity through bright features using specific narrow-band filters to isolate the Ca II K line.
“More than a century of historic Ca II K observations from the Kodaikanal Solar Observatory offer a unique window into the polar magnetic field of the Sun, a key factor governing solar cycles and future solar activity,” said lead author Dibya Kirti Mishra of Aryabhatta Research Institute of Observational Sciences (ARIES) in India.
“Additionally, due to the Earth’s tilt, we only get a really good view of the Sun’s poles a couple of times a year,” said Jha, who helped mentor Mishra during her Ph.D. research, culminating in this paper. “We needed to go back to the past to provide the information we needed to forecast the future. We targeted the Sun’s chromosphere, which has emerged as an indicator of solar magnetic activity.”
Solar astronomers at KoSO began observing the Sun in the Ca II K spectrum as early as 1904. With insufficient modern data to predict activity, scientists were looking for ways to unlock the secrets of solar magnetism hidden in more than a century of KoSO data. The chromosphere just above the Sun’s visible surface forms bright patches and networks associated with magnetic activity.
Each member of the team contributed their expertise to examine the data and connect the dots. Mishra developed an algorithm to automate the image review from the corrected historical data.
“Going through 50,000 images manually would be staggering, so having an algorithm to automatically identify the proxies for the magnetic field was crucial,” Jha said.
“With our current abilities, we can only predict up to five years well in advance, but for NASA or any other space missions, we need to prepare decades or multiple decades before the actual launch to understand expected conditions and plan the mission accordingly,” Jha said. “We will have to wait another four to five years to actually tell how Solar Cycle 26 will behave and if the activity will accurately match our predictions.”
SwRI researchers are proposing a solar polar mission from the ecliptic point of view to directly observe these magnetic mechanisms over time. In the meantime, new insights from this study will help advance space weather forecasting.
To access the article, see: DOI 10.3847/1538-4357/adb3a8.
Another article, which has led to this one, was published last year: https://doi.org/10.1007/s11207-024-02408-6
For more information, visit Heliophysics or contact Deb Schmid, +1 210 522 2254, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.