Sunset is not a single event. It is actually a slow shift through three separate twilight phases, each with its own feel. Most of us think of the sunset as the moment the sun dips below the horizon. But what follows is just as stunning and way more interesting.

Every evening, the sky changes in three parts: Civil, nautical, and astronomical twilight. These aren’t just science terms. They are the reason your backyard glows after sunset, why sailors could steer by stars, and how astronomers know when it is time to grab their telescopes.

Civil Twilight Is the "Normal" Sunset

The first phase of sunset is called civil twilight, and it is the one you already know. It starts right after the sun slips below the horizon, when it is just 0 to 6 degrees under. That sounds tiny, but it matters a lot.

Pixabay / Pexels / During civil twilight, the light in the sky is still strong enough to see clearly, drive safely, or even toss a football around.

This is the golden moment. The clouds catch fire. Everything looks like it is glowing from the inside. This phase lasts about 20 to 30 minutes, depending on where you are and the time of year. It is the most photogenic part of the evening and the reason why "sunset pics" are a thing on your feed.

Nautical Twilight

After civil twilight fades, you step into nautical twilight. This is when the sun drops 6 to 12 degrees below the horizon. The sky darkens, but it isn’t pitch black. This is when brighter stars start to poke through the fading blue, and the horizon line becomes harder to spot.

Long ago, sailors loved this phase of the sunset. It gave just enough light to see the sea while also letting stars come out for navigation. That is why it is called "nautical." The name actually comes from its usefulness at sea, not from how it looks.

Astronomical Twilight

Next comes astronomical twilight, the final stage before true night. Now the sun is between 12 and 18 degrees below the horizon. To the human eye, it feels like night already. But for astronomers, the sky still isn’t dark enough for deep space work.

There is still a whisper of sunlight scattering through the atmosphere. You won’t notice it, but your telescope will. That is why stargazers wait for astronomical twilight to pass before doing serious observations.

Quin / Unsplash / Astronomical twilight is the most peaceful one. It is when everything slows down, when the last birds go quiet and the first crickets take over.

If you look up, you will see a lot more stars now, especially in areas without light pollution.

Why Call Them “Sunsets”

Because technically, each phase is still part of the sunset story. The word "sunset" isn’t just about the sun dropping. It is about how the sky changes because of it. And each of these twilight phases tells a different chapter. Together, they stretch the idea of sunset far beyond just one flash of orange on the horizon.

Even cooler? These phases play in reverse before sunrise. So yes, you also get three "sunrises" every morning, whether you are awake to see them or not.

However, not every sunset lasts the same. The farther from the equator you are, the longer each twilight phase sticks around. Near the poles in summer, twilight can stretch for hours. Near the equator, it is quick and sharp. Blink and you will miss it.

Seasons also change the speed of sunset. In winter, twilight moves fast, while in summer, the light lingers as if it is not in a hurry. That is why summer evenings feel endless, and winter ones feel like someone just hit the lights.