Here's how it works:
* Temperature: Arcturus is a red giant star with a surface temperature of around 4,290 K, while the Sun has a surface temperature of about 5,778 K. This means Arcturus is cooler than the Sun.
* Size: Arcturus is a giant star, with a radius about 25 times larger than the Sun. This massive size makes up for the lower temperature, allowing it to emit much more energy.
* Luminosity: Luminosity is the total amount of light a star emits. Even though Arcturus is cooler, its larger size means it has a significantly higher luminosity, around 170 times greater than the Sun.
Think of it like this: A small, hot stovetop burner will radiate less heat than a large, cooler bonfire. The bonfire, even though it's cooler, has a greater surface area to release heat, making it more powerful overall.
In summary: While Arcturus is cooler than the Sun, its much larger size allows it to emit a significantly higher amount of light, making it more luminous.
