About

Accuracy in solar timing distinguishes professional planning from guesswork. This tool utilizes the NOAA Solar Calculation algorithm to determine the precise position of the sun for any coordinate on Earth. Beyond simple sunrise and sunset, it computes the critical phases of twilight and the specific optical windows known as the Golden and Blue Hours, which are paramount for cinematography, architectural lighting, and outdoor navigation.

Understanding the solar elevation angle is crucial for calculating shadow lengths in construction and determining solar panel efficiency. The calculation engine accounts for the Equation of Time and solar declination, adjusting for atmospheric refraction at the horizon. This data allows users to predict exactly when light conditions will shift from the flat contrast of midday to the dimensional lighting of the late afternoon.

Formulas

The core of the calculation relies on determining the Local Hour Angle (ω). This requires the sun's declination (δ) and the observer's latitude (φ).

cosω = sinα − sinφ sinδcosφ cosδ

For shadow length estimation, where H is the object height and θ is the solar elevation angle:

ShadowLength = H × cotθ = Htanθ

Refraction correction R (in arcminutes) is applied when elevation is low:

R = 1.02tanθ + 10.3θ + 5.11

Reference Data

Solar Event	Elevation Angle (α)	Illuminance (Lux)	Practical Application
Astronomical Twilight	−18°	0.0001	Deep sky observation, absolute dark adaptation.
Nautical Twilight	−12°	0.002	Horizon becomes visible at sea; marine navigation.
Civil Twilight	−6°	3.4	Outdoor reading possible; streetlights typically turn off.
Blue Hour	−4° to −6°	Variable	Cityscapes, cold color temperature photography.
Sunrise / Sunset	−0.833°	400	Geometric center of sun is 50arcmin below horizon.
Golden Hour	6° to −4°	10,000	Warm, diffused light; soft shadows; portraiture.
Solar Noon	Max	100,000	Shortest shadows; maximum UV index.

Frequently Asked Questions

Azimuth is the compass direction of the sun (0° is North, 90° East, 180° South). Elevation is the vertical angle of the sun above the horizon (0° is the horizon, 90° is directly overhead). Together, they define the exact position of the sun in the sky.

Photographers use it to avoid casting their own shadow into a shot. Architects use it to calculate how far a building's shadow will stretch, which impacts zoning laws and light access for neighboring structures.

Yes. In regions above the Arctic Circle (66.5° N/S), the sun may not rise or set for weeks. The tool detects these conditions and labels them as "Midnight Sun" (Polar Day) or "Polar Night".

Geometric sunrise occurs when the center of the sun crosses the horizon (0°). However, visual sunrise is defined as when the upper limb of the sun appears. Combined with atmospheric refraction (which bends light over the horizon), the standard constant adopted by astronomers is -0.833 degrees.

The Golden Hour is not strictly 60 minutes. Its duration depends on your latitude and the season. Near the equator, it passes quickly. Near the poles, the "Golden Hour" can last for several hours.