The fleeting window of light just before the sun rises — and just after it sets. Four moments. Two each day. All of them worth knowing.
Explore ↓The Basics
Twilight is the time when sunlight still illuminates the sky — even though the sun itself is below the horizon. Of the three types of twilight (civil, nautical, and astronomical), civil twilight is the brightest and most practically useful.
It occurs when the geometric center of the sun is between 0° and 6° below the horizon. During this window, there's still enough natural light to see clearly without artificial illumination. The sky glows. Shadows are soft. It's the most visually spectacular time of day.
Every single day, civil twilight happens exactly four times: twice in the morning (beginning and end), twice in the evening (beginning and end). Each moment tells you something different about the available light at your location.
The Geometry
Sun at −6°
Twilight Begins
Sun at −3°
Mid-Twilight
Sun at 0°
Sunrise
Sun > 0°
Daytime
① Morning
Civil Twilight Begins
sun = −6.0°
② Sunrise
Civil Twilight Ends
sun = −0.833°
③ Sunset
Civil Twilight Begins
sun = −0.833°
④ Evening
Civil Twilight Ends
sun = −6.0°
In Depth
The first light of the day. The sun's center is 6° below the horizon — invisible to the eye, but its light begins scattering through the atmosphere and reaching the surface. The horizon becomes faintly distinguishable. Stars near the horizon start to fade. This is the beginning of the end of true night.
The upper limb of the sun appears at the horizon. The −0.833° figure accounts for atmospheric refraction (the atmosphere bends light, making the sun appear ~0.5° higher than it geometrically is) plus the sun's visible radius (~0.267°). This is the official sunrise time published by weather services worldwide.
The sun's upper limb dips below the horizon. Officially sunset. The sky erupts in the longest and most dramatic light of the day — the "golden hour" and "blue hour" both begin here. Light quality becomes warm, directional, and soft. The world glows. This is the moment many photographers plan their entire day around.
The last traces of civil twilight fade. The horizon is no longer distinguishable from the sky without artificial light. Civil authorities use this moment as the legal definition of "night" in many jurisdictions — it's the cutoff for headlight laws, aviation lighting requirements, and outdoor regulations. After this moment, true night begins.
Real-World Impact
The golden hour and blue hour that photographers obsess over happen entirely within civil twilight. The light is warm, directional, and impossibly flattering. Knowing the exact start and end of each window is how professionals plan their shoots.
"Before sunset" and "after sunrise" aren't precise enough for law. Many jurisdictions use civil twilight as the legal definition of day and night — governing when headlights must be on, when certain activities are permitted, and more.
Runners, cyclists, and hikers use twilight times to know when they can safely operate without lights. During civil twilight, the human eye can still perceive the horizon and obstacles — after it ends, you're legally and practically in the dark.
Serious stargazing can't begin until civil twilight ends — the sky is still too bright before then. Astronomers use civil, nautical, and astronomical twilight as precise benchmarks for when different classes of objects become visible.
Crepuscular animals — deer, rabbits, most birds — are most active during the twilight windows. Birdwatching guides schedule dawn and dusk watches around civil twilight begin and end times. Fish feeding patterns follow the light cycle too.
VFR (Visual Flight Rules) pilots use civil twilight as the threshold for day vs. night flying rules. At sea, civil twilight marks the window when both stars for celestial navigation and the horizon are simultaneously visible — critical for sextant readings.
Now on Apple Watch
A Civil Twilight is a standalone Apple Watch app that shows you all four civil twilight times for your exact GPS location — updated daily, calculated entirely on-device. No internet required. No subscription. Just the light, on your wrist.
Today · Mon, Jun 1
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