Granulation: Convective cells ~1000 km across. Bright hot plasma rises at cell centers, cooler plasma descends at dark borders.
Sunspots: Magnetically inhibited convection regions. Appear dark (3500–4500 K) against the 5778 K photosphere. Activity follows an ~11-year cycle.
Differential rotation: Equator rotates in ~25 days, poles in ~35 days. This winds up magnetic field lines, driving activity.
Corona mystery: The corona at 1–3 MK is 200× hotter than the photosphere. Likely heated by wave dissipation and reconnection events.