A luminous star is a celestial body that emits light and energy due to nuclear fusion occurring in its core. This process converts hydrogen into helium, releasing vast amounts of energy in the form of light and heat. Luminous stars can vary in size, temperature, and brightness, with some being much larger and hotter than others. The brightness of a luminous star is often measured using a scale called magnitude. Stars like the Sun are classified as luminous because they are visible from Earth and play a crucial role in supporting life. Other examples of luminous stars include Sirius and Betelgeuse, which are prominent in the night sky.