Final answer:
Sunspots are caused by magnetic fields on the Sun's surface, which impede heat convection, leading to cooler, darker areas. The magnetic activity also sustains a self-perpetuating cycle that allows sunspots to persist.
Step-by-step explanation:
Sunspots are caused by increased magnetic activity on the surface of the Sun, not by hotspots, planetary eclipses, or convection directly. These magnetic fields inhibit the convection processes within the Sun, which usually transport heat to the surface. Due to this inhibition, areas with strong magnetic fields, such as sunspots, are cooler and appear darker than their surroundings.
The leading and trailing sunspots in an active region typically have opposite magnetic polarity, suggesting the rise of magnetic loops from inside the Sun. As hot gases within these loops cool and sink, they establish a self-perpetuating cycle that sustains the sunspots for several weeks.
This explanation aligns with insights provided by helioseismology, a technique allowing scientists to study the interior dynamics of the Sun, which has revealed this complex interplay of magnetic activity and energy transfer processes.