How does a planet differ from a star?

Planets and stars are distinct celestial entities that differ in fundamental ways. A star is a luminous, massive celestial body primarily composed of hydrogen and helium undergoing nuclear fusion in its core. The energy produced from this process results in the emission of light and heat, making stars self-luminous. They often serve as gravitational centers around which planets orbit.

In contrast, planets are non-luminous celestial bodies that do not undergo nuclear fusion. They are significantly smaller than stars and consist of various materials such as rocks, metals, and gases. Planets orbit stars, including our Sun, and their visibility is due to the reflection of the star’s light.

While stars generate their own energy and light through fusion reactions, planets do not possess this capability. Instead, they rely on the light emitted by the star they orbit. Additionally, planets may have moons or natural satellites that orbit them, adding to the complexity of their celestial interactions. The distinction between stars and planets lies in their composition, energy generation mechanisms, and their roles within the larger cosmic structures.