Luminous and Non-Luminous Objects

Luminous objects are objects that emit (produce) their own light. They are a source of light.

Examples:

• The Sun — the primary natural source of light for Earth
• Stars (including the Sun) — produce light through nuclear fusion
• Fire/Flame — a candle flame, campfire
• Electric bulb — converts electrical energy to light
• LED lights, tube lights, neon signs
• Fireflies (Jugnu) — produce light through a biological process called bioluminescence
• Glow worms, some deep-sea fish

Non-luminous objects do not produce their own light. They are only visible because they reflect light that falls on them from luminous sources.

Examples:

• The Moon — reflects sunlight (a very common misconception is that the moon produces light)
• Planets (Mars, Jupiter, etc.) — all visible because they reflect sunlight
• A book, a chair, a human being — visible because they reflect the room's light
• A mirror — reflects light but does not produce it

Common Exam Trick: The Moon is NOT a luminous object. It is the most frequently asked example of a non-luminous body that appears bright.