Why are shadows sharper in direct sunlight?

Answer: Sun acts as point light source

UV rays create sharp edges — Wrong. UV doesn't create sharp shadows. Sharpness comes from nearly parallel light rays because the sun is far away, acting like a point source.

Earth's distance sharpens light — Wrong. Distance doesn't sharpen light rays. But because the sun is distant, its light rays arrive nearly parallel, creating sharp shadow edges (small penumbra).

Sun acts as point light source ✓ — Correct! The sun is so far away (~150 million km) that despite its size, light rays reaching Earth are nearly parallel—effectively a point source. This creates sharp shadows with small penumbra (fuzzy edge). Nearby light sources (bulbs) have diverging rays, creating large penumbra and softer shadows. Distance + size ratio = shadow sharpness!