What is the primary role of a star in the universe?

The primary role of a star in the universe is to produce energy through nuclear fusion. Within the cores of stars, hydrogen atoms fuse together under immense pressure and temperature to form helium, a process that releases substantial amounts of energy in the form of light and heat. This energy is crucial as it not only powers the star itself, allowing it to shine for billions of years, but also provides the energy necessary for sustaining life on planets that might orbit around it.

In contrast, while stars can influence the gravitational dynamics around them, such as creating gravity that affects nearby celestial bodies, gravity itself is a fundamental force of nature rather than a direct role of stars. Additionally, stars do not orbit planets; instead, planets orbit around stars due to this gravitational attraction. Lastly, while stars do play a part in the formation of galaxies, as they are the building blocks of stars and clusters within galaxies, this is secondary to their primary function of energy production through nuclear fusion.