SKY · FIELD GUIDE
Twilight & the Golden Hour, Explained — Dusk, Dawn and the Best Light of the Day
The sky stays light for a while after the Sun goes down, then fades through deepening blue to black. Photographers chase a 'golden hour' and a 'blue hour'; astronomers wait for 'astronomical dark.' What do all these words actually mean — and when do they happen where you are?
We talk about "sunset" as if it's a switch — daylight off, night on. It isn't. The Sun slips below the horizon and then keeps going, sinking further out of sight, and for a good while afterwards the sky stays lit by sunlight scattering through the upper atmosphere. That lingering glow is twilight, and it comes in three named stages that matter to very different people: a dog-walker, a sailor, and an astronomer each care about a different one.
The three twilights
As the Sun drops below the horizon, astronomers measure how far down it has gone in degrees — and draw three lines.
Civil twilight lasts until the Sun is 6° below the horizon. There's still plenty of usable light; you can walk, drive and read outdoors without a torch. The brightest planets — Venus, Jupiter — and a handful of the brightest stars begin to prick through the fading blue. This is the "twilight" most people picture.
Nautical twilight runs from 6° to 12° down. The name is literal: it's the window when sailors could still just make out the line of the sea horizon against the sky to take star sightings, while enough stars were visible to navigate by. The sky overhead is deep blue going on black, and most constellations have appeared.
Astronomical twilight is the last fade, from 12° to 18° down. To the eye it already looks like night, but a sensitive instrument — or a properly dark-adapted observer at a dark site — can still detect a faint wash of sunlight high in the sky. Once the Sun passes 18° below the horizon, that's gone: the sky is as dark as it will get, and the faintest stars, galaxies and the Milky Way are finally within reach.
The golden hour and the blue hour
Photographers run the same clock in reverse, chasing the quality of the light rather than its absence.
The golden hour is the stretch of warm, raking light around sunrise and sunset — roughly while the Sun sits between about 6° above and 4° below the horizon. Because the light is coming in at a low angle, it passes through far more of the atmosphere than midday light does, which scatters away the harsh blues and leaves soft golds, ambers and long, gentle shadows. It flatters faces and landscapes alike, which is why it's so prized.
The blue hour follows immediately after (and precedes it at dawn): the brief window when the Sun is a little further down, around 4° to 6° below the horizon, and the whole sky settles into a rich, even blue. Artificial lights glow warm against it — the classic look of a city at dusk.
Neither is reliably "an hour." Near the equator the Sun plunges almost straight down and the golden and blue hours are brief. At high latitudes near the summer solstice the Sun grazes the horizon at a shallow angle and the golden light can stretch on and on.
Why your times are unique to you
Every one of these moments depends on two things that are personal to you: where you are (your latitude and longitude) and what day it is. The Sun's path across your sky changes a little every day through the year, so sunrise, sunset and each twilight boundary drift continuously — and they differ between even nearby towns. A fixed table can't capture that; the only honest answer is to compute the Sun's position for your exact spot, on the day you're asking. That's what the city pages do.
For the night side of all this — whether tonight is actually worth heading out to stargaze, once you fold in cloud and the Moon — head over to the stargazing-conditions layer, which builds on these same twilight calculations.
Frequently asked questions
What are the three stages of twilight?
They're defined by how far the Sun has sunk below the horizon. Civil twilight (Sun 0 to −6°) is still bright enough to be outside without a light, and the brightest planets appear. Nautical twilight (−6 to −12°) is when the sea horizon becomes hard to make out and many more stars show. Astronomical twilight (−12 to −18°) is the last fade; below −18° the sky is fully dark and the faintest stars and the Milky Way are visible.
What is the golden hour?
The golden hour is the period of warm, soft, low-angle sunlight just after sunrise and just before sunset — roughly while the Sun is between about +6° and −4° relative to the horizon. The light is gentle and flattering because it travels through more atmosphere, scattering away harsh blue light and leaving warm gold and orange tones. It isn't always a full hour: near the equator it can be quite short, while at high latitudes around the solstices it can last much longer.
What is the blue hour?
The blue hour is the short window just after the golden hour ends (and just before it begins at dawn), when the Sun is a little further below the horizon — roughly −4 to −6°. The sky takes on a deep, even blue, and city lights balance beautifully against it. It's a favourite for cityscape and landscape photography.
When does it actually get dark for stargazing?
True darkness arrives at the end of astronomical twilight, when the Sun reaches 18° below the horizon. Only then is the sky free of residual sunlight and the faintest stars, nebulae and the Milky Way become visible. Depending on your latitude and the season, that can be anywhere from about an hour after sunset to — in far-northern or far-southern summer — never, because the Sun doesn't sink far enough.
Why doesn't it get fully dark in summer where I live?
The further you are from the equator, the shallower the Sun's path below the horizon in summer. Above roughly 48–49° latitude, around midsummer the Sun never drops the full 18° needed for astronomical darkness, so a faint twilight glow lingers all night — the 'white nights' of places like Scandinavia, Scotland and southern Canada. The deep-dark sky returns as the nights lengthen toward autumn.
Why are the times different from a neighbouring town?
Sunrise, sunset and the twilight stages depend on your exact latitude and longitude, and they shift every single day as Earth orbits the Sun. Even towns a short distance apart can differ by a few minutes, and the change from one day to the next can be a minute or two. That's why a per-location, per-day calculation — rather than a fixed table — gives you the times that are actually right for where you are.
SEE IT LIVE
Everything in this guide is on the live sky map.