Planning a night under the stars: Moon, planets and dark hours

Guide · Updated 2026-11-10

How Sky tonight works out darkness, the Moon, the planets and the best deep-sky targets for your place and date, with a worked night from Dubai in December 2026.

Open the Sky tonight Free, in your browser, nothing uploaded.

Sky tonight is a one-page plan for an evening of stargazing. Give it a place and a date and it tells you when the sky turns fully dark, how much the Moon will get in the way, which planets are up and when, and a short list of galaxies, star clusters and nebulae that suit the gear you own. It suits beginners with binoculars and telescope owners alike. Once you have picked a target, follow it hour by hour in the target altitude planner, check the month ahead for meteor showers and eclipses in the Sky events calendar, and keep notes of what you saw in the observing log.

What it is

Three things decide whether a night is good for observing: the Sun, the Moon and where your targets sit in the sky.

The Sun. Sunset is not the start of a dark sky. Light keeps leaking over the horizon until the Sun is 18° below it. Between sunset and that point you pass through civil twilight (down to 6°), nautical twilight (12°) and astronomical twilight (18°). The tool calls the time after that “properly dark”.

The Moon. A bright Moon scatters light across the whole sky and hides faint objects. The tool shows its phase as a picture, the percentage of the disc that is lit, and when it rises and sets.

Height in the sky. Every object climbs to its highest point when it crosses your meridian, the north-south line overhead. Higher is better, because you look through less air. Brightness is given as magnitude, a scale where smaller numbers mean brighter objects and each step of 1 is about 2.5 times dimmer.

How to use it

1. Press Change in the place bar and type a city, enter latitude and longitude (and height in metres), or press Use my location. Tick Remember my place on this device if you want it next time.
2. Set Night of to the evening the night begins. Use Times in to show every time in your own time zone or in the place’s local time.
3. Read The night card: sunset, the properly dark window and how long it lasts, sunrise, the Moon’s phase and its rise and set times, plus a one-line hint about what the Moon allows.
4. Look at Planets and the Moon. The table gives each planet’s rise, highest point (time and angle), set, magnitude, constellation and best time tonight. The chart below draws their heights through the night over day, twilight and dark shading.
5. In Best deep-sky objects tonight, pick Eyes, Binoculars, Small telescope or Large telescope, and choose a minimum height of 20°, 30° or 45°. Tap any name to open its full altitude chart.
6. Use the download buttons to save the plan as an image, PDF or Word file for the field.

A worked example

Say you are in Dubai on the night of 13 December 2026, with binoculars, and you set Times in to Dubai’s local time.

The night card shows sunset at 17:30, properly dark from 18:52 to 05:34, which is 10 h 42 min of full darkness, and sunrise at 06:55. The Moon is a waxing crescent, 19 % lit. It rose at 10:43 and sets at 21:14, so the hint reads that it is a dark-Moon night, good for faint targets.

Planets. Saturn (magnitude 0.7, in Cetus) is highest at 19:22, 66° up, so it is the first target after dark. Jupiter (magnitude −2.3) and Mars (0.3) are both in Leo; Jupiter rises at 22:19 and Mars at 22:59, and both stand almost overhead (78° and 77°) just before dawn. Venus, at magnitude −4.8, rises at 03:29 and is 24° up at 05:22. Mercury is greyed out as not well placed.

Deep-sky list (binoculars, higher than 30°). The Pleiades lead the list, highest at 22:32 and 88° up. The Andromeda Galaxy is best early, at 19:32 and 74° up, 78° away from the Moon. The Orion Nebula peaks at 00:32 at 59°, and the Beehive Cluster at 03:32 at 84°.

A sensible plan: Saturn and Andromeda first, the Pleiades and Orion once the Moon has set, then Jupiter, Mars and the Beehive in the small hours.

Where it is used

• School and club observing nights. Teachers check the dark window and Moon before booking a date.
• Astrophotography. Imagers need the Moon down and a target high for hours; the deep-sky table and the altitude chart show both.
• Outreach and public events. Organisers pick the two or three brightest planets that will be up during the event.

Common mistakes

• Treating sunset as dark. Faint galaxies need the properly dark window, often 1 to 2 hours after sunset. Plan from that time.
• Reading the wrong time zone. If you plan from home for a trip, set Times in to the place’s local time so the times match your watch there.
• Ignoring the Moon’s set time. A half-lit Moon that sets at 22:00 still leaves a good late night. Look at moonset, not only the percentage.
• Choosing too low a minimum height. Objects near the horizon look dim and blurred. Keep 30° unless your view is clear and your target is far south or north.

Questions people ask

How exact are the rise and set times? The positions are good to about an arcminute, but a hill, a building or haze on your horizon can easily shift what you see by several minutes. Treat the times as a plan and give yourself a margin.

Does my telescope size change the list? Yes. Each setting lists fainter objects: roughly to magnitude 5 for eyes, 8 for binoculars, 10 for a small telescope and 12.5 for a large one. To see what your own telescope can reach, try the telescope calculator.

Can I use it for the southern hemisphere? Yes. Enter any latitude; highest points then lie due north instead of due south.