A recent NASA study shows that the Sun has been growing more active since 2008. While solar activity typically follows 11-year cycles, it also experiences longer-term shifts that can span decades. For example, solar activity had been steadily declining since the 1980s, reaching a record low in 2008. At the time, scientists believed the Sun was entering an extended period of unusually low activity.
However, the Sun unexpectedly changed direction and began growing more active, according to the study published in The Astrophysical Journal Letters. Researchers noted that this shift could result in an increase in space weather events like solar storms, flares, and coronal mass ejections.
“All indicators suggested the Sun was heading into a long period of low activity,” said Jamie Jasinski, lead author of the study from NASA’s Jet Propulsion Laboratory in Southern California. “So it was surprising to see that pattern reverse. The Sun is gradually becoming more active again.”
Understanding Solar Activity and Its Impact on Space and Earth
The first documented observations of solar activity date back to the early 1600s, when astronomers like Galileo began counting sunspots and recording their variations. Sunspots are cooler, darker patches on the Sun’s surface caused by concentrated magnetic field lines. These regions are typically linked to increased solar activity, including solar flares—powerful bursts of radiation—and coronal mass ejections, which are massive eruptions of plasma that shoot out from the Sun and travel through the solar system.
NASA scientists monitor space weather events because they can impact spacecraft operations, astronaut safety, radio signals, GPS accuracy, and even Earth’s power grids. Predicting space weather is especially important for protecting astronauts and equipment during NASA’s Artemis missions, as understanding the space environment is essential for reducing radiation exposure in space.
Launching no earlier than September 23, NASA’s IMAP (Interstellar Mapping and Acceleration Probe) and Carruthers Geocorona Observatory missions—along with NOAA’s SWFO-L1 (Space Weather Follow On–Lagrange 1) mission—will offer new data and insights to advance space weather research and support future missions to the Moon, Mars, and beyond.
How Solar Activity Affects Planetary Magnetic Fields and Protection
Solar activity influences the magnetic fields of planets across the solar system. When the solar wind—a stream of charged particles emitted by the Sun—and other forms of solar activity intensify, the Sun’s influence grows, causing the magnetospheres of planets to compress. These magnetospheres, which act as protective shields for planets with magnetic cores like Earth, play a crucial role in defending against the plasma jets carried by the solar wind.
Throughout the centuries of observing solar activity, the most inactive periods occurred during a 30-year span from 1645 to 1715 and a 40-year stretch from 1790 to 1830. “We still don’t fully understand why the Sun entered a 40-year minimum beginning in 1790,” said Jasinski. “Long-term solar trends are much harder to predict and remain somewhat of a mystery.”
The Decline in Solar Activity Leading Up to the 2008 Solar Minimum
In the 25 years leading up to 2008, sunspot numbers and solar wind levels declined so significantly that scientists believed the “deep solar minimum” of 2008 might signal the beginning of another prolonged phase of unusually low solar activity.
“But then the decline in solar wind came to an end, and since that point, both plasma levels and magnetic field strength have been steadily rising,” explained Jasinski, who led the analysis using heliospheric data available through OMNIWeb Plus, a platform managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The data used in the study came from a wide range of NASA missions, with two key contributors being ACE (Advanced Composition Explorer) and the Wind mission—both launched in the 1990s. These spacecraft have been monitoring solar activity, such as plasma and energetic particles traveling from the Sun to Earth. They are part of NASA’s Heliophysics Division fleet, which focuses on understanding the Sun’s impact on Earth, space, and the broader solar system.
Read the original article on: Phys.Org