1. What is the NOAA Sunset Time Equation?

The NOAA sunset time equation calculates the approximate time of sunset based on latitude and solar declination. It's derived from astronomical principles and provides the local solar time of sunset.

2. How Does the Calculator Work?

The calculator uses the NOAA sunset equation:

Where:

• \( T \) — Sunset time in hours (local solar time)
• \( lat \) — Latitude in degrees (-90 to 90)
• \( dec \) — Solar declination in degrees (-23.5 to 23.5)

Explanation: The equation calculates the hour angle of the sun at sunset, then converts this to local solar time. The 15 comes from 360° divided by 24 hours (15°/hour).

3. Importance of Sunset Time Calculation

Details: Accurate sunset time prediction is important for agriculture, aviation, photography, outdoor activities, and various scientific applications.

4. Using the Calculator

Tips: Enter latitude (-90 to 90) and solar declination (-23.5 to 23.5) in degrees. The result is in local solar time (24-hour format).

5. Frequently Asked Questions (FAQ)

Q1: What is solar declination?
A: Solar declination is the angle between the rays of the Sun and the plane of the Earth's equator, varying between ±23.5° throughout the year.

Q2: Why does the equation use 12 as a base?
A: 12 represents solar noon (when the sun is highest in the sky). Sunset time is calculated as hours after solar noon.

Q3: How accurate is this calculation?
A: It provides approximate times. Actual sunset can vary due to atmospheric refraction, elevation, and local topography.

Q4: What about daylight saving time?
A: This calculates local solar time. You need to adjust for your time zone and daylight saving if applicable.

Q5: Does this work at all latitudes?
A: It works for most latitudes, but special cases exist for polar day/night when the sun doesn't set or rise.