1. Earth's Rotation:
- The Earth rotates on its axis, completing one full rotation every 24 hours. This rotation causes day and night.
- As the Earth rotates, different parts of the planet face the sun.
2. Sun's Position:
- As the Earth rotates, the sun appears to move across the sky from east to west.
- In the evening, the sun gradually descends towards the horizon.
3. Atmospheric Scattering:
- Sunlight travels through the atmosphere before reaching our eyes.
- The atmosphere contains particles like dust, water vapor, and gases that scatter sunlight.
- Blue light is scattered more effectively than other colors, which is why the sky appears blue during the day.
4. Sunset Colors:
- As the sun sets, the sunlight has to travel through more of the atmosphere.
- This longer path causes most of the blue light to be scattered away.
- The remaining colors, like red, orange, and yellow, are scattered less and reach our eyes.
- These colors create the vibrant hues we see during sunsets.
5. The Horizon:
- When the sun is below the horizon, its light still reaches us, but it is refracted (bent) by the atmosphere.
- This refraction makes the sun appear slightly above the horizon even after it has technically set.
In Summary: Sunset occurs when the Earth's rotation causes the sun to appear to move below the horizon. The colors we see are due to the scattering of sunlight by the atmosphere, with the blue light scattering away and leaving the red, orange, and yellow hues.
