Dawn vs Dusk: Comparison of the Two Twilight Periods

An image the Sun rising over a distant ridge of mountains.

Dawn vs Dusk; Both spans of time equally important but on opposite sides of the day. One symbolic of new beginnings and fresh starts, the other a time to re-energize and reflect.

A general understanding of the transition between night and day can be helpful in many ways, such as planning outdoor activities, photography, observing celestial objects, or just wanting to experience all the spectacular colors often displayed during these times before sunrise and beyond sunset.

Let’s first understand dawn and dusk separately; then, we’ll compare the similarities and differences between these magical times of the day.

Dawn: A New Day

The world begins to stir with early morning light, and nature awakes as the sky begins to glow. Last night’s plans are coming to life as dawn sets the tone for the start of a new day.

This scenario, thankfully, plays out every morning, but “what is dawn”?

What is Dawn?

Dawn is a span of time, a period of twilight before the Sun rises above the eastern horizon. It’s a transitional phase from the darkness of night to the first appearance of the morning Sun.

Nighttime, scientifically referred to as astronomical night, comes to an end once the Sun rises to a point of 18º below the horizon. At this moment, morning twilight or dawn, officially begins.

This period of twilight passes through six stages, all of which are relative to the Sun’s position spanning 18 degrees under the horizon.

Stages of Twilight & Dawn

Phases of Dawn

Astronomical Dawn –  The phase occurs when the geometric center of the Sun rises to 18º below the horizon.
Nautical Dawn – This is the second phase of dawn once the geometric center of the Sun rises to 12º below the horizon.
Civil Dawn – The third and last phase of dawn appears once the geometric center of the Sun rises to  below the horizon.

Astronomical Dawn & Twilight

Astronomical Dawn – A glow of first light permeates the early morning sky but not enough to clearly identify objects in the surroundings. The stars are still on full display.

Astronomical dawn marks the start of the Astronomical Twilight Period when the Sun is between 18 and 12 degrees below the horizon. At this time of astronomical twilight, the sky is still dark but slowly turning a deep blackish-blue near the eastern horizon. Constellations remain visible.

Dawn vs Dusk - An image of astronomical dawn as first light breaks over the eastern horizon
Astronomical Dawn – First light ends the night.

Nautical Dawn & Twilight

Nautical Dawn – It’s the time of day when there’s just enough sunlight for objects to be distinguishable, yet stars are still present in the sky. In many years past, seeing stars while having sight of the horizon was vital for sailors’ navigation using visible landmarks. It’s this relation to sailors that inspired its “nautical” name.

Nautical dawn marks the start of the Nautical Twilight Period when the Sun is between 12 and 6 degrees below the horizon. During nautical twilight, the brightest celestial objects are still visible as the horizon begins to appear.

An image of light breaking over the horizon reflecting off a river of water.
Nautical Dawn – The beginning of nautical twilight.

Civil Dawn & Twilight

Civil Dawn is the time of morning when the geometric center of the Sun rises to only 6º below the horizon. It’s the moment when there’s just enough light for objects to be distinguishable, and outdoor activities can begin. 

The Civil Twilight Period, is when the Sun is between 0 and 6 degrees below the horizon.

There’s now enough light for outdoor activities like jogging or walking, and a favorite for many watching the sky change from deep blues to soft pinks, orange and yellow hues anticipating the moment the Sun peaks over the horizon at sunrise.

An image of civil dawn over Portland, Maine.
Civil Dawn – The beginning of civil twilight in Portland, Maine.

The Period of Dusk

In that short time after the Sun has dipped below the horizon, as daylight and night come together like passing in a hallway, many people are heading home from a day of work and activity.

On that commute home, the sky appears to have a familiar look as when the day began, but is it? What is dusk?

What is Dusk?

Dusk appears on the opposite side of the day from dawn. It begins after the Sun has set below the western part of the horizon at “0” degrees lasting until the Sun moves beyond the angle of 18º, giving way to the night.

There are six different stages of twilight, all relative to the Sun’s position beneath the horizon within the span of 18 degrees.

Stages of Twilight & Dusk

Phases of Dusk

Civil Dusk – The first phase of dusk appears once the geometric center of the Sun sinks to  below the horizon.
Nautical Dusk – This second phase of dusk is reached once the geometric center of the Sun moves to 12º below the horizon.
Astronomical Dusk –  The third and last phase of dusk occurs when the geometric center of the Sun reaches 18º below the horizon.

Civil Dusk & Twilight

The Civil Twilight Period, begins when the Sun is between 0 and 6 degrees below the horizon.

There’s still enough light for outdoor activities like jogging or walking, and a favorite for many watching the sky change from soft orange and yellow hues to purples and blues as the Sun movers lower beneath the horizon.

Civil Dusk is the time after sunset when the geometric center of the Sun drops to 6º below the horizon and is the beginning of nautical twilight.

An image of  a schooner sailing the ocean waters during civil dusk in Key West, FL.
Civil Dusk in Key West.

Nautical Dusk & Twilight

The Nautical Twilight Period occurs as the Sun’s position passes between 6 and 12 degrees below the horizon. At this time, the stars and horizon are very much visible just like this same period during dawn.

Light is much fainter but bright enough for objects to be distinguishable amongst their surroundings. At the beginning of this twilight period, the sky will display a distinctive color of blue, best known to photographers as “The Blue Hour.” It’s famous for how well the deep translucent blue blends nicely with the artificial lighting as people prepare for the arrival of darkness.

Nautical Dusk is the period of twilight after sunset at which the geometric center of the Sun moves to 12º below the horizon. It marks the beginning of astronomical dusk.

An image the coastal town of Manarola Italy furing of the blue hour.
Blue Hour in Manarola, Italy

Astronomical Dusk & Twilight

The Astronomical Twilight Period begins as the Sun transitions between 12 and 18 degrees below the horizon.

During astronomical twilight, the sky has become quite dark and black along the horizon opposite where the sun has set in the west. Artificial light is now needed in most areas as more of the fainter stars and constellations become visible. It’s now possible to begin observing celestial objects in the sky with success.

Astronomical Dusk is when the geometric center of the Sun has dipped 18º below the horizon, and the complete darkness of night has begun.

An image of astronomical twilight before reaching astronomical dusk. Stars are visible above as a glow of orange and white light span the horizon.
Astronomical Twilight before entering Astronomical Dusk

Dawn vs Dusk

A circular diagram demonstrating the transitions of twilight, dawn and dusk.
This diagram demonstrates the transitions of twilight, dawn and dusk.

Mood, Creativity & Inspiration

On any early morning or evening, as twilight has filled the sky, dawn or dusk may evoke various thoughts and feelings within us, from excitement to hope, melancholy or peacefulness. The moods can be many. The quiet and stillness can incite thoughts of reflection on the day or a past time in our life.

These moments of introspection while gazing upon twilight have inspired many creative souls to pay homage as dawn and dusk have moved the pen to paper, brush to canvas, and camera toward the light.

Comparison Table of Dawn vs Dusk

Now that we have taken a closer look at Dawn and Dusk let’s compare the two and identify the similarities and differences we’ve discussed using a table to spotlight.

ComparisonBothDawnDusk
Six Stages of Twilightx
Spans 0-18º below Horizonx
Appears before Sunrisex
Appears after Sunsetx
Sky most affected in the East Horizonx
Sky most affected in the Western Horizonx
Impact Mood, Creativity, Inspirationx
Symbolic of New Beginningsx
Symbolic of Reflective Thoughtsx
Dawn vs Dusk Comparison

How long do Dawn and Dusk last?

The length of time dawn or dusk last depends on your distance from the equator and the season of the year. It’s the span of time it takes the Sun to move a range of 18 degrees, whether moving up from beneath the horizon to a sunrise or sinking further below after sunset until reaching the true darkness of night.

In the lower 48 states of the U.S.—it’s roughly 70 to 100 minutes.

Learn more about how long after sunset it takes to get dark.

Conclusion

Dusk and Dawn are periods of twilight transitions between two halves of the day. As seen in the table chart, they are as equally the same as different. Their main difference is that dawn appears before sunrise and dusk after the Sun has set.

Both are beautiful skies to behold.

A Cityastronomy logo of a cityscape under a starry night with the Cityastronomy name worded across the circular picture.
Written by Darin Anthony

Astronomy has peaked my curiosity and imagination from an early age. I am always thrilled to read about the latest galactic discovery or planning my next celestial observation. More about me [..]

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