What Is Nautical Twilight? (And How It's Different From Civil Twilight)

Nautical twilight is the period when the sun is 6° to 12° below the horizon—darker than civil twilight but brighter than astronomical twilight. During this time, the horizon becomes visible at sea, making it essential for sailors and pilots who need to navigate using stars and the horizon line. Understanding nautical twilight vs civil twilight helps you plan activities that depend on specific light conditions.

If you only need today's sunrise and sunset times, use our Sunrise & Sunset search tool – enter your city to see exact sunrise, sunset, dawn, dusk, and golden hour times for your location.

You may also find these guides helpful:

• Civil, Nautical, and Astronomical Twilight Explained
• What Time Is Dusk Today?

1️⃣ What Is Nautical Twilight?

Nautical twilight gets its name from navigation. For centuries, sailors have used this specific light condition to take accurate readings of stars and the horizon. During nautical twilight, you can see both the horizon and bright stars at the same time, which is essential for celestial navigation.

Here's what happens during nautical twilight:

• The sun is 6° to 12° below the horizon
• The horizon line becomes clearly visible (especially at sea)
• Bright stars are still visible in the sky
• There's enough light to distinguish shapes but not enough for detailed tasks
• Artificial lighting is needed for reading or detailed work

Nautical twilight typically occurs about 40-50 minutes before sunrise in the morning and 40-50 minutes after sunset in the evening. The exact timing depends on your location, the time of year, and your latitude.

2️⃣ What Is Civil Twilight?

Civil twilight is what most people think of when they hear "twilight." It's the period when the sky is still bright enough to see clearly, but the sun has set or hasn't risen yet. During civil twilight:

• The sun is 0° to 6° below the horizon
• There's enough light to see clearly without artificial lighting
• You can read, drive, and do most outdoor activities
• The sky shows beautiful colors (oranges, pinks, purples)
• Streetlights typically turn on or off automatically

Civil twilight happens first—right after sunset and before sunrise. It's followed by nautical twilight, then astronomical twilight. This is the period photographers call the blue hour—when the sky takes on deep blue and purple tones perfect for photography.

For more on photography during twilight, see our guide on golden hour.

3️⃣ What Is Astronomical Twilight?

Astronomical twilight is the period between nautical twilight and true night. During this time:

• The sun is 12° to 18° below the horizon
• The sky is very dark, but not completely black
• The faintest stars begin to fade
• It's still too bright for observing the faintest galaxies and nebulae
• True darkness (astronomical night) begins when the sun is more than 18° below the horizon

For most people, astronomical twilight looks like night. But for astronomers, this period is still too bright for observing the faintest objects. True astronomical darkness only occurs when the sun is more than 18° below the horizon.

4️⃣ Main Differences: Civil Twilight vs Nautical Twilight vs Astronomical Twilight

Here's a clear comparison of all three twilight types:

The key difference between civil twilight vs nautical twilight is brightness and visibility. Civil twilight is bright enough for most activities, while nautical twilight is darker but still allows you to see the horizon for navigation. Nautical twilight vs astronomical twilight differs in darkness level—nautical is lighter and shows the horizon, while astronomical is darker and marks when faint stars begin to fade.

5️⃣ Why Sailors and the Military Use Nautical Twilight

Nautical twilight is critical for navigation because it provides the perfect balance of light and darkness. Here's why sailors and the military rely on it:

Celestial Navigation

During nautical twilight, sailors can see both the horizon line and bright stars simultaneously. This is essential for celestial navigation—using the position of stars, the sun, or the moon relative to the horizon to determine location. Without a visible horizon, these measurements are impossible.

Here's how it works:

1. During nautical twilight, the horizon becomes clearly visible
2. Bright stars (like Polaris, the North Star) are still visible in the sky
3. Sailors use a sextant to measure the angle between a star and the horizon
4. This angle, combined with the time, gives them their exact position

Aviation and Military Operations

Pilots and military personnel also use nautical twilight for similar reasons:

• Visual flight rules: Pilots need to see the horizon for safe navigation
• Mission planning: Military operations often begin or end during nautical twilight for optimal visibility
• Surveillance: The light conditions during nautical twilight provide good visibility without being too bright
• Transition periods: Nautical twilight marks the transition between day and night operations

The military uses specific twilight times to plan operations because they know exactly what visibility conditions to expect. This precision is essential for safety and mission success.

6️⃣ Why Photographers Love Civil Twilight (Blue Hour)

While sailors use nautical twilight for navigation, photographers prefer civil twilight for its beautiful light. This period is often called the blue hour because of the deep blue and purple tones in the sky.

What Makes Civil Twilight Special for Photography

During civil twilight, the sky takes on stunning colors that are perfect for photography:

• Deep blue and purple tones: The sky shows rich, saturated colors
• Soft, even light: No harsh shadows or bright highlights
• City lights contrast: Artificial lights create beautiful contrast against the twilight sky
• Moody atmosphere: Perfect for creating dramatic, cinematic images

The blue hour typically occurs during civil twilight, right after sunset and before sunrise. It's called the blue hour, but it usually lasts about 20-30 minutes, not a full hour. The exact duration depends on your location and time of year.

Civil Twilight vs Nautical Twilight for Photography

Here's why photographers prefer civil twilight over nautical twilight:

• More light: Civil twilight is brighter, making it easier to capture details
• Better colors: The sky shows more vibrant colors during civil twilight
• Easier to work: You can see your camera settings and compose shots more easily
• Longer window: Civil twilight typically lasts longer than nautical twilight

However, some photographers do use nautical twilight for specific effects, like capturing city lights against a darker sky or creating more dramatic, moody images.

For more photography tips, check out our guide on golden hour photography.

7️⃣ Example Timeline: Dawn vs Twilight (Before Sunrise) and Dusk vs Twilight (After Sunset)

Understanding the sequence of events helps clarify nautical twilight vs civil twilight. Here's what happens before sunrise and after sunset:

Morning Timeline (Before Sunrise)

In the morning, twilight happens in this order:

1. Astronomical dawn (sun 18° below horizon)
   About 90 minutes before sunrise. Faintest stars begin to fade. Very dark.
2. Nautical dawn (sun 12° below horizon)
   About 50 minutes before sunrise. Horizon becomes visible. Still quite dark.
3. Civil dawn (sun 6° below horizon)
   About 30 minutes before sunrise. Enough light to see clearly. Beautiful colors appear.
4. Sunrise (sun at 0°)
   The sun's upper edge appears above the horizon. Full daylight begins.

Evening Timeline (After Sunset)

In the evening, the sequence reverses:

1. Sunset (sun at 0°)
   The sun's upper edge disappears below the horizon. Twilight begins.
2. Civil dusk (sun 6° below horizon)
   About 30 minutes after sunset. Still bright enough to see clearly. Blue hour begins.
3. Nautical dusk (sun 12° below horizon)
   About 50 minutes after sunset. Horizon still visible. Getting darker.
4. Astronomical dusk (sun 18° below horizon)
   About 90 minutes after sunset. Faintest stars visible. True night begins.

Dawn refers to the morning twilight period, while dusk refers to the evening twilight period. Both follow the same sequence: astronomical → nautical → civil, but in opposite directions.

For more on dawn times, see our guide on what time is dawn tomorrow.

8️⃣ How to Know When Twilight Happens Today

Finding out when nautical twilight, civil twilight, and astronomical twilight happen today is easy with the right tool. Here's how:

Use SunTimesToday to Find Twilight Times

The easiest way to find twilight times for your location:

1. Go to SunTimesToday and search for your city
2. Open your city's sunrise/sunset page
3. Look for the twilight section showing:
   • Civil twilight start and end times
   • Nautical twilight start and end times
   • Astronomical twilight start and end times
4. Check both morning and evening times—twilight happens twice daily

Each city page shows you the exact times for today, tomorrow, and future dates. This makes it easy to plan activities around specific twilight periods.

For example, if you want to know what time sunset is today near you, you can find that along with all the twilight times on your city page.

Why Twilight Times Change Daily

Twilight times change every day because Earth's position relative to the sun shifts as we orbit. Here's what affects twilight timing:

• Time of year: Twilight times shift with the seasons
• Your location: Latitude and longitude affect when twilight occurs
• Daylight saving time: Clock changes affect when twilight appears on your clock

That's why checking your city page daily gives you the most accurate times. The times update automatically based on your location and the current date.

9️⃣ Frequently Asked Questions

Understanding Twilight Helps You Plan Better

Now that you understand nautical twilight, civil twilight, and astronomical twilight, you can plan activities with confidence. Whether you're a sailor navigating by the stars, a photographer capturing the blue hour, or an astronomer observing faint objects, knowing when each twilight period occurs helps you make the most of the light conditions.

Remember: civil twilight vs nautical twilight differs mainly in brightness and visibility. Civil twilight is brighter and better for most activities, while nautical twilight is darker but essential for navigation. Both happen twice daily—before sunrise and after sunset—and the exact times change every day based on your location.

To find out when twilight happens today for your location, use SunTimesToday to search for your city and view the complete twilight schedule. You'll see civil, nautical, and astronomical twilight times clearly displayed for today and future dates.

Don't let another day pass without knowing when the best light happens. Check your twilight times now and plan your activities around the perfect light conditions.