Methods & sources
Know what the numbers mean.
Sol calculates the geometry of light and interprets a weather forecast — different kinds of answers, each drawn here from your own sky.
Sunrise, sunset & golden hour
Geometric altitude from date and place; sunrise and sunset at −0.833°, golden hour −4° to +6°, blue hour −6° to −4°, sampled by the minute. NOAA's calculation notes The daylight pages draw a year of these events in the clock time of the place's zone: clock changes come from the browser's own zone tables and are marked apart from the sun's motion, and a crossing the clock makes is given with the day the sun alone would have made it.
Window light & shadows
A window sees direct sun when the sun clears the chosen skyline and stands in front of the glass; shadow length is height over the tangent of altitude, drawn to scale.
The moon
Position and phase by Meeus, principal phases to the minute, checked against the U.S. Naval Observatory; the full-moon calendar is open data.
The sunset forecast
Cloud by altitude at your place and at three points along the true sunset bearing, from Open-Meteo, read as words — tendencies, not promises.
Place, time & freshness
Times follow the chosen city; baked answers refresh nightly and every page recomputes live in your browser. The season pages give two conventions and name the local one first: the equinoxes and solstices are computed by Meeus's method to the minute and shown in the place's clock; the calendar seasons are cited from the authority that keeps them — the Bureau of Meteorology, the Met Office, the National Weather Service — and no page implies that a season's first day says anything about the weather.
Using Sol's answers
Geometry is exact to about a minute; forecasts are a call on four rungs, and a computed sunrise is not a promise the sun is visible from your street.
Your address, if you leave it
The launch list keeps four things: the address you type, the minute you typed it, the page you left it on, and your language. They sit in Firestore on Google Cloud so that one email can go out when the app ships. No page can read the list back — the rules that guard it allow one write and no reads at all.
An account is the same address with a password, kept by Firebase Authentication. It holds three things and can hold no more: your address, your two email choices, and the sunset outings you keep. Only you can read it: the rules match each record to its own sign-in and refuse everyone else, this site included. The app does not ship yet and cannot sign in, so for now an account is for this site.
From the bridge on any page a signed-in visitor changes those choices, signs out, removes a kept outing, or deletes the account. Deleting takes the outings, then the record, then the sign-in, and — once the address has been confirmed from the note we send — your place on the launch list, and it says which of them went. Without an account, the one email you receive is the way off the list: reply to it.
Nothing here is shared, sold or handed on, and there are no cookies: a session is a token your own browser keeps, and signing out throws it away.