Show HN: I calculated sun/shade exposure for every seat at World Cup stadiums

Last year, I went to a game at a stadium I had never visited (Arrowhead). Ended up baking in the sun for the entire second half. Afterwards, was surprised I couldn't find a tool that told me where the sun would actually be during games.

So for WC2026 I built SeatSun: a free tool (no sign up needed) that calculates sun/shade exposure for every section at the World Cup 2026 stadiums depending on date and match time.

The technical core: solar azimuth and altitude calculations (based on Meeus astronomical algorithms, ~0.3 degree accuracy) tied to each stadium's orientation and GPS coordinates. For each open-air stadium I mapped the seating sections to compass bearings, then render an interactive overlay showing which sections are in sun vs shade at the exact match time. The sun position shifts meaningfully across a single afternoon -- a 3pm kickoff looks very different from a 6pm kickoff at the same stadium.

Covers 16 stadiums: 13 open-air with interactive sun maps, 3 indoor (AT&T, Mercedes-Benz, NRG) with appropriate notes. You can set any date and kickoff time to see the exposure for your specific game.

Would love feedback on the accuracy, especially from anyone who has been inside these stadiums and can sanity-check the section orientations. A few of the venues were harder to calibrate than others, and I haven’t yet made adjustments other than notes for partially covered stadiums (eg Hard Rock).