The scattering of light in the Earth's atmosphere is responsible for the phenomenon you described. The scattering of light occurs when light interacts with particles or molecules in the atmosphere, causing it to change direction. The extent of scattering depends on the wavelength of light, with shorter wavelengths being scattered more easily than longer wavelengths.
During the day, when the Sun is high in the sky, the Earth's atmosphere scatters sunlight primarily through a process called Rayleigh scattering. This type of scattering is more effective for shorter wavelengths, such as blue and violet light. As a result, the blue light from the Sun is scattered in all directions by the atmosphere, making the sky appear blue to us.
At twilight, when the Sun is lower in the sky, sunlight has to pass through a thicker layer of the Earth's atmosphere before reaching our eyes. The longer path causes more scattering of shorter wavelengths, like blue and green light. As a result, a larger proportion of blue and green light gets scattered away, leaving behind the longer wavelengths of light, such as red and orange. This gives the twilight sky a reddish or orange hue.
The scattering of light is also influenced by other factors, such as the composition and size of particles or molecules in the atmosphere, as well as the angle at which sunlight enters the atmosphere. These factors can contribute to variations in the colors observed during different times of the day or under different atmospheric conditions.