The Sun's surface temperature, known as the effective temperature, is approximately 5,500 degrees Celsius (9,932 degrees Fahrenheit) or 5,773 Kelvin (K). This value represents the temperature of the visible "surface" of the Sun, also called the photosphere. It is important to note that the temperature increases as you move towards the core of the Sun, reaching millions of degrees Kelvin in the core region where nuclear fusion occurs.