Difference Between Twilight and Dusk

Twilight vs Dusk
 

Have you ever wondered if there is a difference between twilight and dusk? Twilight and dusk are words common in English language and are used frequently by people. Twilight is the time before sunrise and after sunset, when there is some amount of light visible in the sky. So technically, though sun has still not risen, we get to see the light in the sky. Also after sunset, when sun is no longer in sight, there remains noticeable amount of light in the sky referred to as twilight period. Twilight can be at dawn and dusk (morning and evening). Many people equate twilight with dusk which is technically not correct. This article attempts to highlight the differences between twilight and dusk.

What is Twilight?

As mentioned earlier, twilight is the time before sunrise and after sunset, when there is some amount of light visible in the sky. If a man says that it is twilight because the sun has set, he is technically correct as there is some amount of light still visible in the sky. On the other hand, the same man can say that it is dark because it is dusk. Even now he is technically correct. To make it easier for the people, the light that we see before the sun has risen in the morning or when it has set and yet there is light in the sky is because of the diffusion of light in the sky even though the sun is below the horizon. There are types of twilight as civil twilight, nautical twilight and astronomical twilight.

Civil twilight starts (in the morning) or ends (in the evening) when the sun is 6 degrees below the horizon.

Nautical twilight (also known as Military Twilight) starts or ends when the sun is 12 degrees below the horizon.

Astronomical twilight tarts or ends when the sun is 18 degrees below the horizon.

Difference Between Twilight and Dusk

What is Dusk?

Dusk is introduced by the Oxford English dictionary as the darker stage of twilight. Dusk marks the end of evening twilight. Dawn is the break of the day, while the day is yet to start in the twilight; the light we see in the sky is because of diffusion of light of the sun when it is still some way behind the horizon. The same phenomenon takes place at the end of the day when twilight occurs just before dusk which is when the sun has set. Twilight is the time before dusk when there is still some light in the sky though sun has gone down below the horizon (again the same phenomenon of diffusion of light). There are three types of dusk as well. They are civil dusk, nautical dusk and astronomical dusk.

Civil dusk begins with sunset and ends when the geometrical center of the Sun goes 6° below the horizon.

Nautical dusk occurs when the Sun goes 12° below the horizon in the evening.

Astronomical dusk is the instant when the geographical center of the Sun is at 18° below the horizon.

What is the difference between Twilight and Dusk?

• Twilight is the time that occurs twice in every 24 hours around dawn and dusk.

• It is the twilight at sunset that we see, and thus speak of it commonly though the same phenomenon is repeated every morning too, when the sun is rising and daybreak has not taken place.

• Twilight is the time when one witnesses soft diffused light in the sky though sun has gone down below the horizon.

• Thus, sunset has taken place, yet we see some light in the sky.

• Dusk finally indicates the beginning of night and end of the day, as twilight also ends and there is no light in the sky.

• Dusk is a part of twilight that indicates twilight is ending, and there is very dim light or even no light in the sky.

• There are three types of dusk: civil dusk, nautical dusk and astronomical dusk.

• There are three types of twilight: civil twilight, nautical twilight and astronomical twilight.

Image Courtesy: Twilight via Pixabay