Eight-week planning horizon

Choose your observing weekend

Isle of Coll · ranked by total moonless dark hours across Friday and Saturday. Seasonal history is context, not the chance of clear weather on those dates.

Natural-dark sky

Site darkness stays separate from the weather and the scheduling order.

21.9–21.9 mag/arcsec²

Next seven nights in detail · Moonless calendar · Milky Way timing

Choose a planet and find its observing times →

Moonless time rank 1

4 Dec – 5 Dec

23.0h moonless / 24.7h astronomical darkness across both nights

December seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

10.7h moonless · Moon 15% lit
Longest moonless stretch: 18:20–05:00

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

12.3h moonless · Moon 8% lit
Longest moonless stretch: 18:20–06:40

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 2

13 Nov – 14 Nov

21.3h moonless / 22.7h astronomical darkness across both nights

November seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

11.3h moonless · Moon 20% lit
Longest moonless stretch: 18:40–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

10.0h moonless · Moon 28% lit
Longest moonless stretch: 20:00–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 3

6 Nov – 7 Nov

21.3h moonless / 21.3h astronomical darkness across both nights

November seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

10.7h moonless · Moon 5% lit
Longest moonless stretch: 19:00–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

10.7h moonless · Moon 2% lit
Longest moonless stretch: 19:00–05:40

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 4

16 Oct – 17 Oct

17.0h moonless / 18.7h astronomical darkness across both nights

October seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

9.0h moonless · Moon 35% lit
Longest moonless stretch: 21:00–06:00

Forecast cloud range: 81–81% at 1 available dark-time samples. Not full-night coverage or a probability.

Saturday

8.0h moonless · Moon 44% lit
Longest moonless stretch: 22:00–06:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 5

20 Nov – 21 Nov

2.3h moonless / 23.3h astronomical darkness across both nights

November seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

2.0h moonless · Moon 84% lit
Longest moonless stretch: 04:20–06:20

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

0.3h moonless · Moon 91% lit
Longest moonless stretch: 06:00–06:20

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 6

27 Nov – 28 Nov

1.7h moonless / 24.0h astronomical darkness across both nights

November seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.0h moonless · Moon 85% lit
No moonless dark window

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

1.7h moonless · Moon 76% lit
Longest moonless stretch: 18:20–20:00

Weather not available for this night. Geometry only; recheck nearer departure.

Moonless time rank 7

30 Oct – 31 Oct

1.7h moonless / 21.3h astronomical darkness across both nights

October seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.0h moonless · Moon 72% lit
No moonless dark window

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

1.7h moonless · Moon 61% lit
Longest moonless stretch: 19:00–20:40

Weather not available for this night. Geometry only; recheck nearer departure.

No moonless darkness

23 Oct – 24 Oct

0.0h moonless / 20.0h astronomical darkness across both nights

October seasonal context
0.0 usable nights/month on average · 2005–2024. Historical regional cloud and darkness, not this weekend’s weather odds.

Night-by-night timing & conditions

Friday

0.0h moonless · Moon 94% lit
No moonless dark window

Weather not available for this night. Geometry only; recheck nearer departure.

Saturday

0.0h moonless · Moon 98% lit
No moonless dark window

Weather not available for this night. Geometry only; recheck nearer departure.

How to use this planner

Choose a weekend with enough moonless time, then check the weather and target outlook before travelling. Times use Europe/London and approximately 20-minute geometry samples. Friday and Saturday are ranked together; hours need not form one continuous window.

The regional NASA climate baseline counts nights with at least three hours of astronomical darkness and mean nighttime cloud at or below 30%. It does not measure telescope seeing or guarantee clear skies. No weather probabilities are inferred from monthly averages. Longer-lead forecasts have coarser sampling.

Full seasonal history and definitions →