NASA’s Parker Solar Probe has completed its 26th close approach to the Sun, providing new data on the structure of the solar atmosphere and how charged particles behave within it. The spacecraft also captured rare evidence of solar material reversing direction and falling back onto the Sun’s surface.
The probe approached within 3.8 million miles of the Sun on December 13, traveling at about 430,000 miles per hour. Mission controllers at Johns Hopkins Applied Physics Laboratory confirmed normal operations after receiving signals on December 18 that the spacecraft had successfully passed through the Sun’s outer atmosphere.
Mapping the Sun’s Boundary
Using seven years of data, scientists created the first detailed maps of the Sun’s Alfvén surface — the boundary where solar material escapes the Sun’s magnetic influence to form the solar wind. The analysis shows that this boundary expands and becomes more irregular when the Sun’s activity increases during its 11-year cycle.
“This mapping effort allows us to see how the solar atmosphere changes over time,” said Sam Badman, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian. He noted that the Parker Solar Probe directly measures plasma and magnetic fields below this boundary, providing key insights into how the corona is heated and how solar wind originates.
Plasma Returning to the Sun
During a coronal mass ejection on December 24, 2024, Parker recorded plasma and magnetic loops curving back toward the Sun — confirming models of solar inflows where magnetic field lines reconnect and pull material inward.
“This is the clearest observation we’ve had of plasma returning to the Sun,” said Nour Rawafi, Parker’s project scientist at Johns Hopkins Applied Physics Laboratory. “It shows how the Sun reconfigures its magnetic fields after an eruption.”
The data allow researchers to measure the speed and density of falling plasma, improving models that predict how coronal mass ejections evolve and how they might affect planets. According to project scientist Angelos Vourlidas, such dynamics influence whether a solar eruption travels toward a planet or moves harmlessly past it.
Parker’s most recent perihelion campaign ran from December 8 to December 18, with its instruments collecting plasma, magnetic, and imaging data. Detailed readings are scheduled for transmission to Earth beginning January 15, 2026.
The Parker Solar Probe mission continues to advance understanding of the Sun’s behavior, contributing to improved forecasting of solar storms that can endanger satellites, power systems, and astronauts.
