How to Use the Stargazing Time Calculator
The best time to observe stars is once astronomical twilight ends and the sky turns fully dark. Right after sunset, lingering light lets only the brightest stars through, but about 90 minutes later, twilight ends and galaxies and faint constellations become visible. Moon brightness matters just as much — a brighter moon raises the sky's background glow and can wash out faint objects. Enter your local sunset time and today's moon age to see the best start time, moon brightness, and expected viewing conditions.
Observing Conditions by Moon Age
| Moon Age | Brightness | Conditions |
|---|---|---|
| 0-5 / 25-29.5 days (near new) | Under 20% | Optimal — galaxies, faint stars |
| 6-11 / 19-24 days | 20-50% | Good — bright constellations, planets |
| 12-18 days (near full) | Over 50% | Fair — bright objects recommended |
Frequently Asked Questions
The sky isn't fully dark until astronomical twilight ends, so faint stars and galaxies stay washed out right after sunset.
Yes — a bright moon raises the sky's background glow and can wash out faint objects. Near full moon, focus on bright planets or the moon itself.