The observatory · computed, never fetched
The time of day.
Everywhere at once.
A board of world clocks — drawn analog faces beside their digital reading — for any of 64 cities on a hand-kept register, each told through the real IANA time zone your own browser carries, so a half-hour zone reads half past and Kathmandu reads its famous :45. Each face wears the sky over that city right now: day, twilight or night, worked out from the sun’s actual altitude.
Below the clocks, an observatory: sunrise, sunset and civil twilight for any city on the register, the moon inked at its current phase, and an orrery of the eight planets you can scrub fifty years either way. Every figure on this page is computed by the page itself, from published astronomical arithmetic — nothing arrives over a wire, so nothing here can break in an outage.
64 cities on the register · the browser’s own IANA zones · NOAA solar arithmetic · a J2000 orrery · zero requests
The clocks
Sixty-four cities. One second hand.
The board opens on sixteen cities and is yours after that — add any city the register knows, retire the ones you don’t watch, walk a clock left or right. The arrangement is remembered in this browser and nowhere else.
World clocks
winding…
—
The sky over each city — day, civil twilight or night, from the sun’s computed altitude — is the word under the time and the hairline along the top of the card. The arrows walk a clock along the board, × retires it, and the arrow on a card opens that one clock in a window of its own. Ticks pause while the tab is hidden.
Sun & moon
Today’s sky, worked out by hand.
Pick a city and the page computes its day: civil dawn, sunrise, solar noon, sunset, civil dusk — drawn as an arc of today’s daylight with the sun placed where it is this minute — and the moon, inked at its current phase. Computed with the NOAA solar equations and the mean lunar cycle, in your browser, from nothing but the date and the register’s coordinates.
The sky desk
Drawn as seen from the northern hemisphere — the lit limb on the right while waxing. The disc is the mean synodic phase; the true moon can lead or lag it by up to about fourteen hours.
Sun times carry the NOAA algorithm’s honest error — a minute or two at mid-latitudes, a few more near the poles, where a degree of refraction is a long stretch of horizon. All times are the city’s own, from its IANA zone.
The orrery
Eight planets, fifty years either way.
A drawn orrery: every planet placed at its computed heliocentric longitude for the date on the scrub, from the JPL mean orbital elements at epoch J2000. Drag the scrub and watch Mercury whip round eight-hundred-odd times while Neptune barely clears a third of its orbit.
The orrery
Not to scale — the spacing between orbits is drawn for reading, not measured; the angles are the computed positions. Elements are the JPL/Standish J2000 table, stated valid 1800–2050 — the outer years of the scrub lean on its slow, known drift. Orbits are drawn as circles; the real ellipses are within a few percent of round.
About
Nothing here can go down.
Every other instrument on labs.llc reads a wire, and says so. This one is the exception, and that is its whole flex: zero upstream. No feed, no key, no proxy — not one figure on this page arrives over a wire. The page computes everything it shows, so an outage anywhere on earth cannot blank a single number. Load it once and it works on an airplane.
The clocks are the browser’s own: Intl.DateTimeFormat against real IANA zone names, which is the same tz database — DST rules, half-hour zones, Nepal’s :45 — that your operating system keeps current. The register of 64 cities is hand-kept in the page: name, zone, coordinates, nothing else.
The sun figures use the NOAA solar position equations — declination and the equation of time from the Julian century, rise and set at zenith 90.833°, civil twilight at 96° — good to a minute or two at mid-latitudes, honestly worse near the poles. The moon disc is the mean synodic phase, reckoned from the new moon of 6 January 2000 at 18:14 UT; the real moon runs an eccentric orbit and can lead or lag the mean by up to about fourteen hours, which is stated on the panel rather than hidden. The orrery runs on the JPL approximate Keplerian elements — Standish’s J2000 table with per-century rates, stated valid 1800–2050 — with Kepler’s equation solved on each scrub. What the arithmetic cannot honestly say, the page does not draw.
Your board of clocks and your chosen sky city are remembered in this browser and nowhere else. A link to the page can carry a city or an orrery date with it.