GoodSeeing Guides
Sun below −18° · next 30 nights

True darkness at NamibRand Nature Reserve

Astronomical darkness starts only when the Sun is 18° below the horizon. These bars are calculated for the coordinates, so high-latitude nights correctly show no true darkness when twilight never ends.

Longest night9.0 h10 Oct
Nights reaching −18°30 / 30Astronomical darkness occurs
Longest window20:20–05:20Moonlight is shown separately in the planner.
Solar geometry, not a clock rule

Hours of astronomical darkness

10 Oct9.0 h0% moon
11 Oct9.0 h2% moon
12 Oct9.0 h6% moon
13 Oct9.0 h11% moon
14 Oct9.0 h18% moon
15 Oct8.7 h26% moon
16 Oct8.7 h34% moon
17 Oct8.7 h43% moon
18 Oct8.7 h53% moon
19 Oct8.3 h62% moon
20 Oct8.3 h72% moon
21 Oct8.3 h80% moon
22 Oct8.3 h88% moon
23 Oct8.3 h94% moon
24 Oct8.3 h98% moon
25 Oct8.3 h100% moon
26 Oct8.3 h99% moon
27 Oct8.3 h96% moon
28 Oct8.3 h91% moon
29 Oct8.3 h83% moon
30 Oct8.3 h73% moon
31 Oct8.3 h62% moon
1 Nov8.3 h50% moon
2 Nov8.3 h39% moon
3 Nov8.3 h28% moon
4 Nov8.3 h19% moon
5 Nov8.3 h11% moon
6 Nov8.3 h5% moon
7 Nov8.3 h2% moon
8 Nov8.3 h0% moon
9.0 hours

Use this as the outer boundary for faint-object work. Moon altitude, cloud and transparency will narrow the practical window. Add the Moon →

Keep planning

Same coordinates, different question

Moon

Moonless nights

Find the longest uninterrupted dark windows.

Core

Milky Way

See when the galactic core clears the horizon after dark.

−18°

Astronomical darkness

Track true darkness, including polar twilight.