# Golden Hour & Light Direction Calculator

A free tool from Stargazing Hub (lightpollutionmap.app) that gives the golden hour
and blue hour times for any location and date — and, unlike most calculators, the
exact compass direction (azimuth) the light comes from.

Tool: https://lightpollutionmap.app/golden-hour

## Definitions (NOAA / U.S. Naval Observatory)

- Golden hour: the period when the Sun's centre is between −4° and +6° of the
  horizon. Light is warm, low and strongly directional. Best for portraits,
  landscapes and warm side/back light.
- Blue hour: the deeper twilight when the Sun is between −6° and −4° of the
  horizon. The sky turns cobalt and balances with artificial light — best for
  cityscapes, architecture and light trails. It lasts only ~20–30 minutes.

These windows occur twice a day (morning and evening) and their length depends on
latitude and date: near the poles in summer they can last for hours or merge into
continuous twilight; near the equator they are short and consistent year-round.

## What makes this tool different: light direction

For each phase the tool reports not just the time but the Sun's compass bearing
(azimuth, 0° = north, 90° = east, 180° = south, 270° = west). It also draws a
sun-path "dome": the outer ring is the horizon, the centre is overhead, and the
Sun's whole arc for the day is plotted with the golden and blue bands coloured.

How to use the direction:
- The light comes from the Sun's bearing. Subjects facing that bearing are
  front-lit. Turn 180° from it for back-light, rim-light and silhouettes.
- For a ridge or building edge to be rim-lit, place the subject to the side of the
  line between you and the Sun.
- The lower the Sun, the longer the shadows and the more three-dimensional a scene
  looks.

## Accuracy

Times and azimuths are computed with a high-precision astronomical engine
(arc-second class, equivalent to Meeus/VSOP87 algorithms), the same calculations
used in the Compass Altimeter app.

## Frequently asked questions

Q: Which way should I point my camera during golden hour?
A: The light comes from the Sun's bearing shown by the tool. Face that bearing for
front light; turn 180° for back-light, rim-light and silhouettes.

Q: Blue hour is so short — how do I make it count?
A: It lasts ~20–30 minutes and the light is dim, so use a tripod and a 2–10 second
exposure. The cobalt sky and city lights balance in colour temperature then — the
best window for cityscapes and light trails.

Q: How do I use the light direction to pick a spot?
A: The bearing points at the Sun. For side/back light put your subject to the side
of the line between you and the Sun; for warm front light, shoot with the Sun
behind you. Arrive ~10 minutes early because the light changes fast.

Q: Is it free and how accurate is it?
A: Free, no ads, no sign-up. Arc-second-class astronomical accuracy. For offline
use in the field, live bearings and an AR sky, see the Compass Altimeter app
(iOS App Store id 6752685064; Google Play com.knockdream.compass).

## Related

- Light pollution map: https://lightpollutionmap.app/
- Compass Altimeter app (Apple): https://apps.apple.com/us/app/compass-altimeter-sun-moon/id6752685064
- Compass Altimeter app (Google Play): https://play.google.com/store/apps/details?id=com.knockdream.compass