# Your Sunset, Their Sunrise 🌅 🌄

**URL:** <https://talk.observablehq.com/t/your-sunset-their-sunrise/10851>\
**Category:** Show and tell\
**Created:** [September 14, 2026, 7:59pm UTC](https://talk.observablehq.com/t/your-sunset-their-sunrise/10851 "2026-09-14T19:59:53Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![MarioDelgadoSr](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/mariodelgadosr/32/1828_2.png) [@MarioDelgadoSr](https://talk.observablehq.com/u/MarioDelgadoSr)\
**Post date:** [September 14, 2026, 7:59pm UTC](https://talk.observablehq.com/t/your-sunset-their-sunrise/10851/1 "2026-09-14T19:59:53Z")

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[https://observablehq.com/@ambassadors/your-sunset-their-sunrise](https://observablehq.com/@ambassadors/your-sunset-their-sunrise)

Every day, somewhere on Earth, your sunrise is someone else’s sunset. This notebook finds those two points for you: given your location, it draws two spots on your same latitude line — one to the west having its sunrise the moment you have your sunset, one to the east having its sunset the moment you have your sunrise.

It’s built as a flat Mercator map showing your pin and both paired points at once, with an option to switch to a rotatable 3D globe. Under the hood it’s pure spherical geometry — latitude and today’s solar declination — cross-checked live against an independent astronomical library so the math validates itself as you move around.

Big thanks to **[@neocarto](https://observablehq.com/@neocarto/-/collection/geoviz)** for [Geoviz](https://github.com/riatelab/geoviz), which powers the map rendering here. Along the way I dug into its data-driven tooltip and symbol APIs to get proper hover tooltips and a custom pin marker working on the maps. Observable AI was also a big help in prototyping and debugging:

 ![image](https://canada1.discourse-cdn.com/flex030/uploads/observablehq/original/2X/8/8a3493e386bcf987960186f4741c3d1fb579cfa3.png)