Moon
Explanation
In optics, objects are classified based on their ability to generate light. Luminous bodies are objects that emit their own light due to internal processes (such as nuclear fusion, chemical reactions, or electrical heating). Non-luminous (or illuminated) bodies do not produce their own light; they become visible only when they reflect light from a luminous source.
Analysis of Options:
- Sun: The Sun is a star that generates massive amounts of energy and light through nuclear fusion reactions in its core. It is a natural luminous body.
- Fire: Fire is the result of a chemical combustion reaction that releases energy in the form of heat and light. It is a luminous source.
- Electric lamp Electric lamp: An electric lamp converts electrical energy into light energy (through incandescence or fluorescence). It is an artificial luminous body.
- Moon: The Moon is a natural satellite and a non-luminous body. It does not generate its own light. It appears bright in the night sky solely because it reflects sunlight falling on its surface.
Key Takeaway:
The Moon is a non-luminous celestial body that is visible only due to the reflection of sunlight, unlike stars or artificial light sources which emit their own light.