Why Does the Sun Appear Brighter Than Rigel?

Question:

Why does the Sun appear brighter than Rigel to an observer on Earth?

Answer:

The Sun appears brighter than Rigel from Earth because it is much closer to us. Even though Rigel is much more luminous, its light is spread over a large distance, decreasing its apparent brightness.

To an observer on Earth, the Sun appears brighter than the star Rigel because it is much closer to us than Rigel. The sun is about 149.6 million kilometers away from Earth. On the other hand, Rigel, a blue giant star in the Orion constellation, is located 860 light-years away. Despite the fact Rigel is much more luminous than the Sun, this luminosity is spread out over a vast amount of space by the time it reaches us, making it appear less bright from our perspective. Furthermore, the apparent brightness of a celestial body as seen from Earth is determined not only by its intrinsic brightness or luminosity, but also by its distance from Earth. The farther away an object is, the dimmer it appears. This is known as the inverse-square law of light, which states that the intensity of light is inversely proportional to the square of the distance from the source of that light.