Why does the sun have sunspots?

Answer: Magnetic fields reduce heat

Shadows from passing planets — Wrong. Planets don't cast shadows on the sun—they're tiny compared to it. Sunspots are magnetic phenomena on the sun's surface.

Nuclear reactions slow down — Wrong. Nuclear fusion in the core continues steadily. Sunspots are surface features where magnetic fields prevent hot plasma from rising.

Magnetic fields reduce heat ✓ — Correct! Sunspots are cooler regions (~3,800K vs ~5,800K photosphere) appearing darker. They form where strong magnetic fields (thousands of times Earth's) emerge from sun's interior, inhibiting convection—preventing hot plasma from rising. Magnetic activity follows 11-year solar cycle. Sunspot counts vary with cycle. Despite being cooler, sunspot regions often produce solar flares and coronal mass ejections!