Sun and Calendar · 7 of 9

White Nights

Why do June nights in the far north never get properly dark?

Why June nights in the far north never get properly dark, where the midnight Sun begins, and why Quito's nights hardly change all year.

You’ll be able to say how dark a summer night gets from any latitude, and why.

7 steps · about 5 min

Where and which night

Working out when this is best placed from where you are…

Where

Which night

Date

Time

Kept for this guide only, until you change it here — your map settings, and every other guide, stay as they are.

Print, play outside or present

Present on a big screen

Scan with a phone's camera, or open

Sources

US Naval Observatory — rise, set and twilight definitions: civil, nautical and astronomical twilight at 6°, 12° and 18°
JPL Horizons — the Sun's altitude from London, Oslo, Tromsø and Quito, which the charts are tested against
Meeus, Astronomical Algorithms, 2nd ed. (1998), ch. 15 and 25 — rising, setting and the Sun's position
Norway Tourism — midnight Sun and polar night dates by town, Tromsø included

← GUIDES

More below ↓

With a keyboard, focus the sky, aim it with the up and down arrow keys, and press Enter to drop the pin at the centre of the view; or press Show me.

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Settings

Screen

Night mode Turns every page red, to keep your eyes adjusted to the dark.

High contrast Bolder constellation lines, larger and brighter names on the sky, and stronger text and edges everywhere. Starts on if your device asks for more contrast.

Reduce motion The camera cuts to where it is going instead of flying there, and panels and sheets appear without sliding. Starts on if your device asks for less motion.

Battery saver Draws the sky thirty times a second at most: smoothness traded for battery.

Night brightness Dims the screen below your phone’s lowest setting, down to a fifth, while night mode is on.

Clock and voice

Clock How every time is written. Until you choose, your language’s own clock decides.

D describes What D says about the view on the sky: one sentence, or in full with the field, the constellation and five names.

Sounds Quiet tones as you use the map: a tick as you drag the clock past a mark or dusk, a chime for the star you pick — higher for hotter stars — and a low swell while a figure is out of the dome. Made in your browser, and off until you turn them on.

All settings and your progress

Midnight at the June solstice, facing north: the mark is the Sun. St Petersburg named its white nights: the Sun never sinks far enough for dark. Walk north: higher at each stop, and at Tromsø's latitude it never sets.

That night's Sun at three latitudes, drawn on your sky, then unrolled into height by your clock. Night is only truly dark with the Sun 18° down, and none of the three dips that far.

Your own year, a night per column, shaded by depth: civil to 6°, nautical to 12°, astronomical to 18°, then true night. If it pinches shut on the dotted line, you get white nights. If not, you are too near the equator; step 6 says where they begin.

The Sun's lowest point each night, for you and three others. Tromsø's climbs over the horizon in June, and its noon sinks under in December. Quito's never comes near: true night all year. Ushuaia's is the mirror: no true night in December.

The same evening from sunset, facing west. At Quito's latitude the Sun drops straight down, and it is dark 69 to 75 minutes later, every evening of the year. At Oslo's in June it slides along the horizon and never gets 18° down.

Midnight depth is 90° − latitude − 23.4°. North of 48.6° it stays under 18°; Paris, at 48.9°, just makes the cut. North of 65.7° the Sun never sets, a degree short of the Arctic Circle, because the air lifts its image.

The solstice midnight once more. On your summer solstice, note how late true dark comes.

True night needs the Sun 18° down
No true night poleward of 48.6°
At the equator, dark within the hour