Tap any point on the map and see the full solar day there: sunrise, sunset, twilight, golden hour, live sun position. A time slider scrubs through the day and the sun marker, shadow arrow and daylight wedge on the map move with it. Zoom out to see the global day/night line sweep across the earth. 500 city pages plus dedicated pages for today, tomorrow, the next eclipse and the next solstice. Handles polar regions, every time zone and DST. Free, no signup, open source.
Hi Product Hunt,
I built Solarc because I was planning a few weekend hikes last year and kept tab-flipping between sun apps, a weather app and a tide chart. What I actually wanted was simpler: tap a point on a map and see the whole solar day for that exact spot, at any date.
The first version was a one-page calculator. You typed a city, you got times. It worked, but it felt like every other sun calculator on the web. The day I drew the sunrise and sunset azimuths as a wedge on the map I realised that was the actual product. The map is not a decoration; it is the answer. You can see in two seconds whether a ridge will block the view, where shadows will fall, how the sun path will swing between June and December from that exact viewpoint.
Things grew from there. A time slider so you can scrub through the day and watch the sun marker move on the map. A daylight wedge so you can plan a viewpoint visit. Solstice arcs in the same frame so you can plan a year ahead. Then a global day/night terminator when you zoom out, which started as a debugging visualisation and stayed because it was useful.
The harder part was the long tail. Polar day, polar night, daylight saving transitions, every IANA time zone, the next solar eclipse with per-city visibility. None of those are interesting individually; together they are what stops people from saying "this is wrong" in some niche they care about. Astronomy Engine does the math, Luxon handles time, and 325 tests pin the edge cases.
It is free, no signup, no tracking until you accept cookies, MIT licensed. The whole map runs on OpenFreeMap tiles so no Google or Mapbox key is needed.
What I would love feedback on:
- Anything that feels confusing or buried
- Whether the city pages and the today / tomorrow pages cover the search you would actually run
- Bugs at high latitudes or near the date line
Brutally honest welcome.
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