Sol Light

Answers questions about natural light anywhere: tonight's sunset colour forecast, hours of sun on a window, golden hour, the moon and shadow length. No key or account.

View on solocene.com

Documentation

Ask your assistant about the light.

Sol’s instruments as tools any assistant can call: the same arithmetic this site uses, for any place on Earth, running on your own machine. No account, no key and no telemetry.

Nine tools.

  • sun_timesSunrise, sunset, solar noon, day length, the bearings, golden and blue hour, for any date.
  • light_nowDaylight, golden hour, blue hour or night this minute, and what comes next.
  • sunset_callTonight’s sunset in one of four words, with the reasons, from a live forecast.
  • sunset_outingThe whole evening as one plan: when to arrive, which way to look, golden hour to last light, and a link to send.
  • sun_on_windowHours of direct sun by the way a window faces, today, at midsummer and at midwinter.
  • room_sunlightThe room behind the window: how much of the floor the sun covers, and how deep it reaches.
  • compare_placesOne instant in two to twelve places, and the hours when the sun is up in all of them.
  • moon_tonightPhase, how much is lit, where it stands, moonrise and moonset, and the next full moon.
  • shadow_lengthThe length and direction of a shadow at a given time, and when it equals the height.

Install.

Claude Desktop, Claude Code, Cursor and anything else that speaks MCP over stdio. Node 20 or newer.

{ "mcpServers": { "sol-light": {
    "command": "npx",
    "args": ["-y", "--package=https://solocene.com/mcp/sol-light-mcp.tgz", "sol-light-mcp"]
} } }

Claude Code, in one line:

claude mcp add sol-light -- npx -y --package=https://solocene.com/mcp/sol-light-mcp.tgz sol-light-mcp

The package: sol-light-mcp.tgz · its version and checksum. It will be on npm as sol-light-mcp; the arguments then become ["-y", "sol-light-mcp"].

Then ask.

  • Is it golden hour in Lisbon right now?
  • Will the sunset be worth watching in Chicago tonight?
  • How much sun does a south-facing window get in Oslo in December?
  • How long is my shadow in Tokyo at 4 pm?
  • When is the next full moon in Sydney?
  • Where does the sun set in Reykjavik on the solstice?

How it answers.

A place is any city name or a pair of coordinates with a time zone. Sol’s own cities answer at once in their own zone; any other name is found through Open-Meteo’s geocoder. Times come back both as instants and as local clock times.

The sunset forecast reads live weather from Open-Meteo and judges it by the same method as this site. Nothing else leaves your machine.

Explore the light

Every instrument