Tonight's sky: when does it get dark, and what is the moon doing?

By Kevin Buhl Jakobsen · Everything is worked out in your browser; your location never leaves your device

When is it actually dark?

It doesn't get dark the moment the sun sets. Sunlight is scattered by the atmosphere long after, and astronomers split the evening into three kinds of twilight:

• Civil twilight (sun 0–6° below the horizon): you can still read outside, and the brightest planets appear.
• Nautical twilight (6–12°): the horizon over the sea fades away, and the well-known constellations become clear.
• Astronomical twilight (12–18°): the sky looks dark to most people, but the faintest stars and the Milky Way are still missing.

Only when the sun is more than 18° below the horizon is it fully dark. In Denmark the sun doesn't get that low at all from late May to mid-July — that's why the summer nights are light, with a northern sky that never turns fully black.

The moon decides how many stars you see

A full moon lights up the sky so much that only the brightest stars show. To see the Milky Way or shooting stars, choose a night with a new moon, or one where the moon rises late. The tool shows the hours when the sky is dark and the moon is down or only dimly lit. Read more in the article The winter night sky in Denmark.

Tips for a night under the stars

• Get away from the lights. Street lamps and the glow of a town turn the sky grey. Just 20 minutes into the countryside makes a big difference.
• Give your eyes 20 minutes. Eyes adapt to the dark slowly. Use red light on your phone, and don't look at the white screen.
• Dress warmly. Even in summer it gets cold when you stand still at night.

The times are worked out with simplified astronomical formulas and are normally right to within a couple of minutes. Mountains, buildings and the weather are not included.