WHY IS THE SKY BLACK AT NIGHT?
The light we see on earth is light from the sun. The earth rotates once every 24 hours. It is dark when the observer is on the side away from the sun. We may see some light due to the light reflected from the moon.
The sky appears black at night because there is no direct sunlight to illuminate it. During the day, sunlight scatters off the molecules in Earth's atmosphere, causing the sky to appear blue. However, when the sun sets and drops below the horizon, the sunlight can no longer reach our location, resulting in a dark sky.
If you want to understand the phenomenon in more detail, you can consider the following:
1. Earth's Rotation: The Earth rotates on its axis, causing different parts of the planet to face towards or away from the sun. When you are on the side facing away from the sun, it is nighttime.
2. Absorption of Light: The atmosphere contains gases and particles that absorb and scatter sunlight. During the day, this scattering of shorter blue wavelengths of light by the atmosphere makes the sky look blue. However, at night, when there is no direct sunlight, the lack of scattering means that the dark space beyond becomes visible, making the sky appear black.
3. Light Pollution: In certain areas with significant artificial light sources, such as cities, the night sky may not appear completely black due to light pollution. Human-made lights scatter and reflect off particles in the air and can cause the sky to appear brighter or have an orange glow.
In summary, the sky appears black at night because there is no direct sunlight, and the absence of scattering makes space visible.