Slow Solar Wind Structures Shock with High Speeds (Image Credits: Unsplash)
European Space Agency scientists have captured unprecedented views of the Sun’s atmosphere, revealing that structures in the slow solar wind accelerate far more rapidly than previously modeled. The Proba-3 mission’s artificial eclipses allowed detailed tracking of plasma movements just 70,000 kilometers above the solar surface. This breakthrough challenges long-held assumptions about solar wind origins and could transform predictions of space weather.[1][2]
Slow Solar Wind Structures Shock with High Speeds
Plasma blobs in the inner corona reached velocities of 250 to 500 kilometers per second, three to four times the anticipated 100 kilometers per second near the Sun’s surface. Researchers tracked these gusts using high-resolution videos compiled from images taken every one to two minutes. The observations exposed small-scale dynamics previously unseen in optical wavelengths so close to the Sun.
“In the inner corona, a region very difficult to observe, we saw slow solar wind gusts moving three to four times faster than expected,” stated Andrei Zhukov, principal investigator for the ASPIICS instrument at the Royal Observatory of Belgium and lead author of the study.[1] Arrows in data visualizations indicated accelerations as these blobs moved outward, with some slowing upon approach to the Sun. Shaded uncertainty regions highlighted the variability in directions and speeds. This gusty behavior underscores the non-uniform nature of slow solar wind formation.[2]
Proba-3’s Innovative Eclipse Formation Flight
The mission consists of two satellites flying in precise formation: the Coronagraph satellite equipped with the ASPIICS instrument and the Occulter satellite that blocks the Sun’s disk. Launched in December 2024, Proba-3 achieved its first artificial eclipse in July 2025. By April 2026, the pair had completed 57 such eclipses, amassing over 250 hours of corona footage – equivalent to observations from roughly 5,000 Earth-based total solar eclipses.
ASPIICS peers closer to the Sun than predecessors like SOHO’s LASCO or Solar Orbiter’s Metis, reaching down to one-tenth of a solar radius with superior resolution and minimal stray light. Each eclipse lasts about five hours, enabling continuous monitoring without the Sun’s glare. Joe Zender, ESA’s Proba-3 project scientist, noted: “These intricate movements have never been observed in optical wavelengths so low in the Sun’s inner corona.”[1]
- Formation flying precision: Satellites maintain alignment over 150 meters apart.
- Imaging cadence: 1-2 images per minute for dynamic videos.
- Additional instruments: DARA measures solar energy output; 3DEES studies radiation belt electrons.
- Data access: Publicly available via sidc.be for further analysis.
Distinguishing Fast and Slow Solar Wind
Fast solar wind streams smoothly from coronal holes at higher speeds, while slow solar wind emerges gustily from equatorial streamers – bright rays formed by tangled magnetic fields. Magnetic reconnections in these streamers merge and separate field lines, ejecting plasma blobs outward. Proba-3 data confirmed this process in action, revealing ubiquitous small-scale structures driving the variability.
Traditional models underestimated accelerations in this region, where space weather events like coronal mass ejections originate. The wide range of observed speeds and directions explains past difficulties in pinpointing slow solar wind sources. Streamers appeared prominently in images toward the corona’s top center-right and bottom left.[1]
| Solar Wind Type | Origin | Typical Speed (km/s) |
|---|---|---|
| Fast | Coronal holes | >500 |
| Slow (expected near surface) | Streamers | ~100 |
| Slow (Proba-3 observed) | Inner corona blobs | 250-500 |
Implications for Solar Physics and Space Weather
The study, published March 9, 2026, in The Astrophysical Journal Letters, demands revisions to theories on coronal magnetic fields and plasma acceleration. Zender remarked: “We can track how solar wind speeds up close to the Sun, we see it all over Proba-3’s field of view, and we have already seen speeds and accelerations that surprised us.”[2] Most of the mission’s data remains unprocessed, offering vast potential for probing coronal heating and mass ejections.
Enhanced understanding of inner corona dynamics will improve space weather forecasts, protecting satellites and power grids from solar storms. Theoretical models must now incorporate these rapid gusts to match observations. Zhukov added: “Slow solar wind is naturally not uniform, involving lots of small-scale structures in the Sun’s magnetic field that we can see thanks to ASPIICS.”[1]
Proba-3 marks a leap in heliophysics, delivering hours of pristine corona views per orbit. As analysis continues, these findings lay groundwork for decoding the Sun’s atmospheric mysteries. What aspects of solar wind research intrigue you most? Share in the comments.
Key Takeaways:
- Proba-3’s eclipses enable unique inner corona observations down to 70,000 km.
- Slow solar wind blobs hit 250-500 km/s, defying 100 km/s expectations.
- Discovery fuels model updates for space weather and coronal physics.