Astronomy Practice Exam 2025 – All-in-One Guide to Master Your Astronomy Test!

The feature on the Sun characterized as relatively cool spots on its surface is sunspots. These areas appear darker than the surrounding regions because they are cooler, with temperatures around 3,000 to 4,500 degrees Celsius, compared to the Sun's surface temperature of about 5,500 degrees Celsius. Sunspots form in regions of intense magnetic activity, which inhibits the flow of heat from the Sun's interior to its surface. Consequently, this leads to a significant temperature difference, making sunspots observable as darker patches against the bright solar surface.

In contrast, prominences are large, bright features extending outward from the Sun's surface, associated with magnetic activity but are much hotter than sunspots. Solar flares are sudden and intense bursts of radiation and energy from the Sun's surface, also linked to magnetic activity but do not have the cooler, darker characteristic of sunspots. The corona, which is the outermost layer of the Sun's atmosphere, is actually much hotter than the surface itself, reaching temperatures of several million degrees, further distinguishing it from sunspots.