India’s Aditya-L1 solar mission has provided new evidence that may help explain why the Sun’s outer atmosphere, the corona, is far hotter than its visible surface and remains heated despite frequent energy-losing eruptions. The findings matter because coronal mass ejections can produce auroras but also trigger geomagnetic storms that disrupt power grids and satellites.

Researchers say energy reaches the corona through waves generated by boiling motions on the Sun’s surface and through magnetic field lines that break and reconnect. The corona is typically about 2 million°C, compared with roughly 5,500°C at the photosphere, and can occasionally reach 40 million°C; the Sun produces two to three coronal mass ejections daily at low activity, rising to 10 or more during peak periods in its 11-year cycle.