Amid Earth's challenges, the Sun has enjoyed a relatively quiet period. Recent analysis by leading solar experts confirms our star entered a new phase—Solar Cycle 25—starting December 2019.
Since the mid-18th century, astronomers have tracked the Sun's approximately 11-year activity cycle, marked by peaks and troughs. Sunspots, driven by its intricate magnetic field, serve as key indicators. This will be the 25th documented cycle.
Earlier this year, the U.S. Space Weather Prediction Center (SWPC) noted 30 straight days without sunspots, signaling the cycle's onset. Researchers at India's IISER Kolkata corroborated this, observing the solar magnetic field's reversal in early 2020.
A panel of NASA and NOAA experts, after rigorous review, officially declares December 2019 as the start of Cycle 25.
The determination relied on monthly sunspot data from the World Data Center for the Sunspot Index and Long-term Solar Observations at Belgium's Royal Observatory in Brussels.
Solar activity is now ramping up toward the next maximum, forecast for July 2025. Doug Biesecker, NOAA's Space Weather Prediction Center solar physicist and panel co-chair, anticipates Cycle 25 matching the previous "below-average" cycle in strength.
Even so, "a below-average cycle doesn't preclude extreme space weather events," Biesecker notes. "The Sun's influence on Earth is tangible—we monitor it around the clock because it can always surprise us."
For a visual journey, astronomers have compiled Solar Dynamics Observatory (SDO) images from June 2, 2010, to June 1, 2020, into a time-lapse video. Each second captures one day of solar activity—you might spot Venus's transit on June 6, 2012.
