New York, USA
Lat: 40.71°•Lon: -74.01°
ASTRONOMICAL DARK SKY
11:17 PM
True darkness begins; sky is free of atmospheric solar skyglow
First Light (Civil Dawn)11:49 AM
Sunrise12:20 PM
Solar Noon04:59 PM
Sunset09:38 PM
Last Light (Civil Dusk)10:09 PM
True Night (Astro Dusk)11:17 PM
Astronomical Dusk Calculator (Start of True Night)
Sun Sinks Past -18°•Start of True Astronomical Night•Milky Way Visibility Window•Total True Darkness Hours Counter
Calculate When True Astronomical Darkness Begins Tonight
Astronomical dusk occurs when the sun drops 18 degrees below the horizon in the evening, concluding astronomical twilight. At this precise moment, all sunlight has completely left the atmosphere, allowing the Milky Way and distant deep sky objects to reach maximum natural contrast.
Plan star parties, planetary alignments, and long-exposure astrophotography with automated calculations of total dark sky hours tonight.
How to Use the Astronomical Dusk Calculator
1
Enter your stargazing location or dark sky park coordinates.
2
Find the exact timestamp when the sun dips below -18°.
3
Track the live countdown to the start of unpolluted deep-sky observing.
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Frequently Asked Questions
What is astronomical dusk?
Astronomical dusk is the instant in the evening when the center of the sun reaches 18 degrees below the horizon, ending astronomical twilight and beginning true night.
Is there any sunlight left after astronomical dusk?
No, after astronomical dusk, no sunlight illuminates the sky. The only ambient light comes from stars, airglow, the zodiacal light, and the Moon if present.
Does astronomical dusk occur every night everywhere?
No, during summer at latitudes higher than roughly 48.5 degrees, the sun never descends 18 degrees below the horizon, meaning true astronomical night does not occur.
Ready to Use the Astronomical Dusk Calculator?
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