NASA’s Parker Solar Probe completed its 28th close approach to the Sun on June 8, again matching its record distance of 3.8 million miles from the solar surface. The flyby allowed the spacecraft to continue its measurements of the solar wind and solar activity at their source, while adding to our understanding of how the Sun’s atmosphere changes throughout the solar cycle.

The spacecraft checked in with flight controllers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland — where Parker Solar Probe was designed and built — on Thursday, transmitting a beacon tone that indicated its systems were operating normally. Zooming around the Sun on a trajectory that limited communications with Earth, Parker had been out of contact and operating autonomously for nine days around its closest approach, as planned.
 
During this solar encounter, which started June 3 and ends Saturday, June 13, Parker’s four scientific instrument packages gathered data from inside the Sun’s atmosphere, or corona. Parker will begin returning detailed spacecraft telemetry on June 14, with science data transmission set to run from Wednesday, June 17 to Tuesday, June 30.
 
Parker’s observations of the solar wind and solar events, such as coronal mass ejections and the aftermaths of flares, are critical to advancing humanity’s understanding of the Sun and the phenomena that drive high-energy space weather events that pose risks to astronauts, satellites, air travel, and even power grids on Earth. Understanding the fundamental physics of space weather enables more reliable prediction of astronaut safety during future deep-space missions to the Moon and Mars.
 
Parker also equaled its record-setting speed of 430,000 mph — a mark that, like Parker’s distance to the Sun, was set during a close approach on Dec. 24, 2024, and matched during five flybys since, most recently on March 11. Parker will continue matching these speed and distance records during future flybys.
 
Through all six close approaches, mission leads say, the spacecraft has remained in excellent condition. While Parker doesn’t have a temperature sensor on the front of its heat shield — known as the Thermal Protection System, or TPS — the team can estimate through models that the heat shield reaches temperatures of about 1,700 degrees Fahrenheit at closest approach.

“The heat shield material is incredibly light and fragile, but the thermal design, as well as the software that keeps the spacecraft pointing the TPS toward the Sun, have been outstanding,” said John Wirzburger, Parker Solar Probe mission systems engineer at APL. “It’s a real tribute to the team that designed, built, and operates Parker Solar Probe.”
 
Meanwhile, the team can measure the temperature of the barrier blanketing below the heat shield, and the actual spacecraft temperature has remained consistent on each pass.
 
“That temperature consistency is a major indicator of spacecraft health,” said Wirzburger. “It tells us the heat shield isn’t degrading. If it were cracking or weakening, we’d see temperatures drift upward as more heat leaked through.”
 
Parker launched in August 2018. At the time, the Sun was near the minimum of its 11-year activity cycle. In 2024, representatives from NASA, the National Oceanic and Atmospheric Administration (NOAA), and the international Solar Cycle Prediction Panel announced that the Sun had reached its solar maximum period. Parker’s 28 encounters with the Sun reflect this change over time, sampling the Sun’s atmosphere from quiet to very active periods. Parker Solar Probe will remain in this orbit around the Sun and continue making observations into the declining phase of solar activity.
 
The next steps for the mission in late 2026 and beyond are under NASA review.
 
Parker Solar Probe was developed as a part of NASA’s Living With a Star (LWS) program to explore aspects of the Sun-Earth system that directly affect life and society. The LWS program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins APL manages Parker Solar Probe for NASA and designed, built, and now operates the mission.
 
Mike Buckley, Johns Hopkins Applied Physics Laboratory

The post Parker Solar Probe Makes 28th Close Pass of Sun appeared first on NASA Science.

Forecasting solar flares is one of the major challenges facing solar physicists today. New research finds that non-thermal emission can precede a solar flare by more than an hour, and this early emission may signal whether the flare will be accompanied by an explosion of plasma.

Flare Flavors

Solar flares come in two basic flavors: eruptive and confined. Eruptive flares are accompanied by the launch of tangled clouds of plasma and magnetic fields called coronal mass ejections. Confined flares, so called because the solar plasma remains confined to the Sun, feature only a brief blast of high-energy radiation.

Both solar flares and coronal mass ejections can disrupt everyday life on Earth, with flares knocking out radio communications and coronal mass ejections threatening spacecraft electronics and power grids. Given these real-life risks, as well as the potential for probing the physics behind the activity on the Sun and other stars, it’s critical to be able to identify signs of upcoming flares.

Looking at the Lead-Up

Luckily, there’s growing evidence that the Sun sends out subtle signals that a flare is soon to happen. One early sign of an impending flare is an increase in the non-thermal velocity of the plasma at the flare’s location. This phenomenon has been spotted in individual flares, but it hasn’t been studied and characterized for a large sample of flares — until now.

A recent research article led by Andy S. H. To (European Space Agency) takes the first systematic, large-scale approach to studying the non-thermal velocity changes that precede solar flares. The team amassed a sample of 1,449 solar flares that were seen by the Hinode spacecraft, the Geostationary Operational Environmental Satellite (GOES), and the Solar Dynamics Observatory (SDO). Hinode provided the spectral information needed to identify increases in the non-thermal velocity, GOES provided the flare start times, and SDO provided detailed information on the location and appearance of each flare.

Of the flares in the sample, 83% were moderately powerful C-class flares, 18% were stronger M-class flares, and 1% were the most powerful X-class flares. To’s team identified a clear trend across all types of flares: the non-thermal velocity increases 4–25 minutes before the flare’s X-ray emission begins to rise, peaks when the X-ray emission peaks, and decays as the flare decays. The team found some evidence that for smaller flares, the velocity increase begins in spectral lines that trace cooler plasma before spreading to lines probing hotter plasma, but more work is needed to confirm this trend.

More Details

Certain flares give even earlier hints of upcoming activity. M-class flares and some C-class flares exhibit what To’s team calls “precursor emission,” which emerges roughly 30–60 minutes before the flare’s X-ray emission peaks. The team also identified differences in precursor emission between confined and eruptive flares: eruptive flares display precursor emission over a broad range of spectral lines starting 45–74 minutes before the flare peaks, while confined flares show precursor emission later (31–54 minutes before peak) and in only a few spectral lines.

These results suggest that changes in the non-thermal velocity of solar plasma can not only signal when and where a flare is likely to arise, but also whether the flare will be accompanied by a potentially destructive coronal mass ejection. Upcoming missions like the Multi-slit Solar Explorer and SOLAR-C will give an even better view of the early stages of solar flares, helping to illuminate the physics behind them and enhancing our ability to forecast them.

Citation

“Systematic Nonthermal Velocity Increase Preceding Soft X-Ray Flare Onset: A Large-Scale Hinode/EIS Study,” Andy S. H. To et al 2025 ApJ 993 102. doi:10.3847/1538-4357/ae07de

The post How Solar Flares Hint That They’re About to Happen appeared first on AAS Nova.