surface of the Sun that emits light and heat), is about 5,500°C (9,932°F). This is the visible surface layer we see when looking at the Sun. However, the Sun's temperature varies across its different layers: Core: The core, where nuclear fusion occurs, is much hotter, reaching around 15 million°C (27 million°F). Corona: The Sun's outer atmosphere, called the corona, is surprisingly hotter than the surface, reaching temperatures of about 1 to 3 million°C (1.8 to 5.4 million°F). This is still a bit of a mystery, as it is much hotter than the surface despite being farther from the core.