When we look up at the starry sky, we discover that among countless stars, some shine brightly while others are dim; their brightness varies significantly.
Explaining Why Stars Shine
There are two factors that determine the brightness of stars: the intrinsic luminosity of the stars themselves and their distance from Earth.
Astronomers have categorized the luminosity of stars into 25 distinct classes, with the brightest stars being up to 10 billion times more luminous than the faintest. However, regardless of how powerful a star’s luminosity is, if it is too far from Earth, it may appear dimmer than stars with significantly lower luminosity that are closer to us.
For instance, there is a star named Betelgeuse, which has a volume 220 million times that of the Sun and is approximately 50,000 times more luminous than the Sun. Despite this, it is located about 410 light-years away from Earth. Due to this vast distance, it appears only as a flickering red star when observed from our planet. However, if Betelgeuse were placed in the position of the Sun, everything on Earth would be incinerated by its immense heat.
