Blue Hour vs Twilight
Blue hour and twilight are closely related, but they are not identical. One is a photography term; the other is an astronomical period.
The difference
Twilight covers the full period when the sun is below the horizon but the sky is not fully dark. It includes civil, nautical, and astronomical phases.
Blue hour is the visually useful blue-toned part photographers often plan around. It usually overlaps with part of twilight.
Which one should you plan with?
Use blue hour when your goal is photography timing. Use twilight phases when you need a broader view of visibility and darkness.
For cityscapes, blue hour is usually the more practical planning term.
Frequently asked questions
Can blue hour happen during civil twilight?
Yes. Blue hour often overlaps with civil twilight and may extend toward nautical twilight.
Is twilight always blue?
No. Twilight can include warm, pink, purple, or dark tones depending on conditions.