This striking image, captured by NASA's **Solar Dynamics Observatory (SDO)** using its Atmospheric Imaging Assembly (AIA) instrument at the **193 Ångstrom wavelength**, reveals the Sun's outer atmosphere, or corona, on March 10, 2026 (timestamped 23:34:04 UTC). In this extreme ultraviolet view, hotter plasma glows brightly, while cooler, less dense regions appear as dark voids—prominently featuring a large **trans-equatorial coronal hole** labeled #31, with a smaller one (#30) near the northern limb.
Coronal holes are not literal gaps in the Sun but regions where the solar magnetic field opens outward into interplanetary space, allowing charged particles (solar wind) to escape at high speeds—often 500–800 km/s, far faster than typical solar wind. This particular hole spans across the solar equator from northeast to southeast quadrants, creating an elongated, irregular dark patch that dominates the disk. Such trans-equatorial structures are more common near solar maximum in **Solar Cycle 25** (peaking around 2025–2026), when magnetic complexity drives varied coronal features at lower latitudes.
For scale, the Sun's diameter is approximately 1.39 million kilometers (about 109 Earth diameters). Large coronal holes like this can extend hundreds of thousands of kilometers—easily encompassing areas equivalent to dozens of Earths. The dark appearance arises because the plasma here is cooler (~1 million K vs. surrounding hotter material) and thinner, emitting less in the observed wavelength.
This Earth-facing coronal hole is geoeffective: fast solar wind streams from it are forecast to arrive around midday March 13, 2026, potentially elevating geomagnetic activity to **G1 (minor storm)** levels (Kp index up to 5). High-latitude auroras become more likely (probabilities up to 50–65% in regions like northern North America, Scandinavia, and southern New Zealand/Tasmania), with quieter conditions expected March 11–12 before the onset.
The inset 3-day geomagnetic forecast (from SolarHam) reflects this: quiet to unsettled March 11–12, then active to minor storm March 13, with higher high-latitude aurora odds.
Coronal holes drive recurrent space weather patterns during the solar cycle, offering reliable opportunities to study solar wind origins and magnetospheric responses—without the explosive drama of flares or coronal mass ejections.
**Image credit:** NASA's Solar Dynamics Observatory (SDO)/AIA, 193 Å channel, via
SolarHam.com (composite and annotations). Forecast details courtesy of NOAA/NWS Space Weather Prediction Center and SolarHam.
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