Blue hour is the twilight period when the sun is just below the horizon, and the sky takes on a deep blue tone. Golden hour is when the sun is low above the horizon, producing warmer, golden-colored light.

A practical rule of thumb is to think in terms of civil twilight: around the horizon to about 6° above or below it. If the sun is slightly above the horizon, you’re in golden-hour territory; if it’s slightly below, that’s blue hour.

There isn’t a fixed one-hour duration for either. The length varies with latitude and season, so it may be quite short in some places and much longer in others.

In look and feel, golden hour gives warm, soft light and golden tones, while blue hour gives cooler, bluer ambient light after sunset or before sunrise. In casual use, people sometimes use these terms a bit loosely, and some photographers may include adjacent twilight periods when talking about “golden hour” or “blue hour.”