What causes twilight and dawn?

Hint: The period of time between sunrise and dawn, or between sunset and dusk, is known as twilight. This is the time of day when there is neither complete daylight nor complete darkness, and just a small amount of light is visible in the sky. When the sun rises and sets, it distributes light through the atmosphere, resulting in dusk and dawn.

Complete answer:
The scattering of sunlight off the atmosphere causes twilight and dawn. Twilight and dawn are times when the sky is dark and little light is visible.
Explanation:Twilight is the illumination of the lower atmosphere when the Sun is below the horizon and not directly visible. Twilight is caused by sunlight scattering in the high atmosphere, illuminating the lower atmosphere and preventing the Earth's surface from being entirely lighted or dark. When the sun rises and sets, it distributes light through the atmosphere, resulting in dusk and dawn.

Additional Information: The twilight grows darker as the Sun descends below the horizon (other factors such as atmospheric conditions being equal). When the Sun is \[{18^ \circ }\] below the horizon, the brightness of twilight is virtually zero, and evening twilight turns into night time. Night time turns into morning twilight as the Sun gets \[{18^ \circ }\] below the horizon again.

Note: It's important to note that twilight exists because Earth has an atmosphere. Even after the sun has set, some light scatters via microscopic particles in the atmosphere, leaving some light in the sky. By analogy with evening twilight, the word twilight is also used metaphorically to signify that something is weakening and reaching its conclusion.