Sun below −18° · next 30 nights

True darkness at Alice Springs

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 night8.3 h3 Nov

Nights reaching −18°30 / 30Astronomical darkness occurs

Longest window20:20–04:40Moonlight is shown separately in the planner.

Solar geometry, not a clock rule

Hours of astronomical darkness

3 Nov8.3 h31% moon

4 Nov8.3 h21% moon

5 Nov8.3 h13% moon

6 Nov8.3 h7% moon

7 Nov8.3 h3% moon

8 Nov8.3 h0% moon

9 Nov8.3 h0% moon

10 Nov8.3 h2% moon

11 Nov8.3 h6% moon

12 Nov8.3 h11% moon

13 Nov8.0 h17% moon

14 Nov8.0 h25% moon

15 Nov8.0 h33% moon

16 Nov7.7 h42% moon

17 Nov7.7 h52% moon

18 Nov7.7 h62% moon

19 Nov7.7 h72% moon

20 Nov7.7 h81% moon

21 Nov7.7 h88% moon

22 Nov7.7 h94% moon

23 Nov7.7 h98% moon

24 Nov7.7 h100% moon

25 Nov7.7 h99% moon

26 Nov7.7 h95% moon

27 Nov7.7 h88% moon

28 Nov7.7 h80% moon

29 Nov7.7 h70% moon

30 Nov7.7 h59% moon

1 Dec7.7 h47% moon

2 Dec7.7 h36% moon

8.3 hours

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

Change location

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.