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Understanding Twilight: Examples and Phases

June 18, 2026 · The Clime Team
Understanding Twilight: Examples and Phases

Twilight is the period between day and night when the Sun is below the horizon, yet its light scatters in the atmosphere, illuminating the sky. This phenomenon occurs twice daily: before sunrise and after sunset. Understanding twilight is essential for activities like photography, navigation, and astronomy.

What Are the Phases of Twilight?

Twilight is divided into three distinct phases, each defined by the Sun's position below the horizon:

  1. Civil Twilight: This is the brightest phase, occurring when the Sun is between 0° and 6° below the horizon. During civil twilight, there is enough natural light for most outdoor activities without artificial illumination.

  2. Nautical Twilight: Occurring when the Sun is between 6° and 12° below the horizon, nautical twilight is characterized by the horizon being indistinct at sea, making it challenging for sailors to distinguish between the sea and the sky.

  3. Astronomical Twilight: This phase happens when the Sun is between 12° and 18° below the horizon. During astronomical twilight, the sky is dark enough for astronomers to observe celestial objects without interference from the Sun's light.

Examples of Twilight Times in U.S. Cities

Twilight times vary based on geographic location and the time of year. Here are examples of twilight times for several U.S. cities on June 18, 2026:

  • Los Angeles, CA:

  • Civil Twilight: 5:12 AM – 5:41 AM

  • Nautical Twilight: 5:41 AM – 6:12 AM

  • Astronomical Twilight: 6:12 AM – 6:41 AM

  • New York, NY:

  • Civil Twilight: 5:21 AM – 5:52 AM

  • Nautical Twilight: 5:52 AM – 6:22 AM

  • Astronomical Twilight: 6:22 AM – 6:52 AM

  • Houston, TX:

  • Civil Twilight: 5:30 AM – 6:00 AM

  • Nautical Twilight: 6:00 AM – 6:30 AM

  • Astronomical Twilight: 6:30 AM – 7:00 AM

  • Miami, FL:

  • Civil Twilight: 5:30 AM – 6:00 AM

  • Nautical Twilight: 6:00 AM – 6:30 AM

  • Astronomical Twilight: 6:30 AM – 7:00 AM

  • Chicago, IL:

  • Civil Twilight: 5:30 AM – 6:00 AM

  • Nautical Twilight: 6:00 AM – 6:30 AM

  • Astronomical Twilight: 6:30 AM – 7:00 AM

These times are approximate and can vary slightly based on specific locations within each city and atmospheric conditions. For precise twilight times, it's advisable to consult local astronomical data or online calculators.

Why Is Twilight Important?

Twilight holds significance in various fields:

  • Photography: The soft, diffused light during twilight provides ideal conditions for capturing images with balanced exposure and rich colors.

  • Navigation: Sailors and pilots use twilight phases to determine their position and orientation when celestial bodies are visible.

  • Astronomy: Astronomers rely on astronomical twilight to observe celestial objects without interference from the Sun's light.

Understanding twilight phases and their timings is essential for planning activities that depend on natural light conditions.

Frequently Asked Questions