Using various telescopes, astronomers discovered a giant star that is 100 times larger than the Sun, and is very hot. It is blue-white in color. Why does the Sun appear brighter than this larger star when viewed from Earth?

- The Sun is older than the larger star
-The Sun is closer to Earth than the larger star**
- The Sun is made of different elements that the larger star

you are correct

The correct answer is: The Sun is closer to Earth than the larger star.

To understand why the Sun appears brighter than a larger star even though it is smaller in size, we need to consider a few factors.

Firstly, the apparent brightness of a star is dependent on both its intrinsic brightness (also known as luminosity) and its distance from Earth.

The intrinsic brightness of a star is determined by factors like its size, temperature, and composition. In this case, you mentioned that the larger star is very hot and blue-white in color, suggesting that it has a high temperature and emits a lot of energy. However, the Sun, although smaller, has a lower temperature and emits less energy compared to this larger star. Hence, the larger star may have a higher intrinsic brightness.

However, the distance factor plays a crucial role. The Sun, being the closest star to Earth, is only about 93 million miles away. On the other hand, the larger star discovered by astronomers could be much farther away, possibly several light-years. This difference in distance significantly affects the perceived brightness.

The intensity of light decreases as it spreads out from its source and covers a larger area. This phenomenon is known as the inverse square law of light. When a star is farther away from us, its light gets spread out over a larger area, resulting in a decrease in its apparent brightness. In contrast, the Sun, being closer, has its light concentrated over a smaller area, making it appear brighter from Earth.

Therefore, the Sun appears brighter than this larger star, primarily because it is closer to Earth, despite being smaller in size and having different properties.