Final answer:
A glowing ball of gas powered by nuclear fusion in its core is known as a star, like our Sun.
Step-by-step explanation:
A glowing ball of gas held together by its gravity and powered by nuclear fusion in its core is a star. This definition explicitly refers to celestial bodies like our Sun, which generate vast amounts of energy through nuclear reactions deep within their cores.
The Sun, for example, maintains its high temperature and energy output for billions of years through the fusion of hydrogen. Stars play a crucial role in the cosmos, and understanding their properties helps us grasp the mechanisms behind stellar evolution and the larger celestial dynamics.