1. What is the Sunset/Sunrise Time Equation?

The sunset/sunrise time equation calculates the time difference from solar noon when the sun rises or sets based on latitude and solar declination. It's fundamental for astronomy, navigation, and daylight planning.

2. How Does the Calculator Work?

The calculator uses the sunset/sunrise equation:

Where:

• \( T \) — Time in hours from solar noon
• \( lat \) — Latitude in degrees (-90 to 90)
• \( dec \) — Solar declination in degrees (-23.5 to 23.5)

Explanation: The equation calculates the hour angle when the sun is at the horizon, which is then converted to time from solar noon.

3. Importance of Sunrise/Sunset Calculation

Details: Accurate sunrise/sunset times are crucial for agriculture, photography, religious observances, outdoor activities, and energy management (solar power).

4. Using the Calculator

Tips: Enter latitude (-90 to 90 degrees) and solar declination (-23.5 to 23.5 degrees). The result shows hours from solar noon (positive for sunset, negative for sunrise).

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° and +23.5° throughout the year.

Q2: Why divide by 15 in the equation?
A: The Earth rotates 15 degrees per hour, so dividing the hour angle by 15 converts it to time in hours.

Q3: What about atmospheric refraction?
A: This basic calculation doesn't account for atmospheric refraction, which makes the sun appear higher than it actually is when near the horizon.

Q4: How accurate is this calculation?
A: It provides theoretical values. Actual sunrise/sunset times vary due to topography, atmospheric conditions, and observer elevation.

Q5: What's the difference between sunrise and sunset times?
A: The calculation gives the same absolute value for both, with sunrise occurring before solar noon and sunset after.