DARK HOURS
Alerts
Sky brightness now
18.36mag/□″
naked eye to 4.3
Tonight01:21 CDT

Fair

Usable if you stay local. The window opens at 22:21.

Held back by light pollution, nothing much is in the way.

Score
55
out of 100
Best window
22:21
until 04:21 · 6 h
Moon
87%
Waning Gibbous
True dark
5 h 36 min
0% moonless
20:0021:0022:0023:0000:0001:0002:0003:0004:0005:0006:00
MoonMilky Way coreAstronomical nightBest window01:21 · 56 this half-hour

A night is not one thing. Grade the window you actually have.

The time you actually have

20:30 – 21:10
Not worth it

Honestly, no. Real darkness does not start until 22:16.

It is not astronomically dark at any point in this window, that starts at 22:16.

Up in that window

Night at a glance

☀Sunset20:21
◐Civil twilight ends20:50
◑Nautical twilight ends21:31
●Astronomical night22:16 – 03:52
◒Nautical twilight begins04:37
☀Sunrise05:46
Waning Gibbous
87% lit · rises 21:44 · sets –
Of your 5 h 36 min of true dark, 0% is moonless.
Computed here

Sun, Moon, planets, twilight and the Milky Way come from published astronomical algorithms (Meeus; JPL Keplerian elements), checked against the US Naval Observatory to within two minutes on rise, set and transit.

Fetched

Weather and pressure-level fields from Open-Meteo. Planetary K index from NOAA SWPC. Both answered.

Modelled, with error bars

Light pollution is modelled from population, not satellite radiance. Leave-one-out cross-validated against published sky-quality readings: RMSE 0.49 mag/arcsec² out of sample, 0.31 rural, 0.69 urban, worst case 1.2. It reads about one Bortle class too dark near mid-size cities. Sky brightness under moonlight follows Krisciunas & Schaefer (1991). Seeing is a proxy from upper-level wind, not a measurement.