topic Re: Looking to Find True Sunrise for a Location in Developers Questions

Looking to Find True Sunrise for a Location

JohnJames9 — Sun, 25 Jan 2026 20:23:58 GMT

I wandered into here in order to be able to identify the real sunrise for a location, given lat/lon coordinates, for any day of the year. This is probably the wrong project to start with, but here I am!

My home is close to a mountain range, and my sunrise is roughly an hour after the sunrise data one can fetch just using a lat/lon point. I was interested in crafting a map with geographic data and then learn how to plot such a thing given a date/time.

Given I'm foolishly making this my first project, I'm wondering what components are involved, at which point I can start searching for tutorials.

Re: Looking to Find True Sunrise for a Location

ToddW_stl — Sun, 25 Jan 2026 23:21:33 GMT

this makes me think of a military application @ArthurCrawford told me years ago, where the analysis was to find a route for helicopters to fly through a mountain range in the shadows, to avoid reflections from the moonlight at night. my initial thought is something similar, where you find sunrise/sunset, and adjust for seasonal shadows. have fun! remember to share what you come up with here!

Simulate daylight and weather tutorial

Assess shadow impact - 3D analysis documentation

Re: Looking to Find True Sunrise for a Location

DavidSolari — Mon, 26 Jan 2026 17:43:24 GMT

Did some digging around and found two really good links.

First is this old college course that covers the math involved in calculating the sun's position relative to Earth, among other things. If you're interested in the mathematical foundations this looks like a good starting point. Link.

Second is pvlib, a Python library that models many aspects of photovoltaic phenomena, including the sun position given a certain date and location. You can either add the library to your Python environment and use the functions as-is (docs) or go diving through the source code to see how it's implemented (link).

Re: Looking to Find True Sunrise for a Location

Noah-Sager — Thu, 29 Jan 2026 19:05:35 GMT

Sounds like a fun project. I think choosing something you can get passionate about will help you overcome the technical hurdles. To add on to the good ideas already here, there is also the Day/Night Terminator, although I haven't played around with this in years.

https://community.esri.com/t5/arcgis-living-atlas-blog/introducing-day-night-terminator/ba-p/1220971

https://www.arcgis.com/home/item.html?id=59403010eeff4d1bb838ca58d4dcb16c

Re: Looking to Find True Sunrise for a Location

ToddW_stl — Sat, 31 Jan 2026 01:39:36 GMT

that's cool - I didn't even know that was a thing!

Re: Looking to Find True Sunrise for a Location

ToddW_stl — Tue, 10 Feb 2026 16:24:10 GMT

I also recently saw this on LinkedIn (which might be related to my Shadow Impact link above) - https://www.linkedin.com/posts/courtneyyatteau_arcgis-gis-3d-activity-7424175168408772609-aLeR?utm_source=share&utm_medium=member_desktop&rcm=ACoAAESsHlkBrUtgLKIcj7qinu_QKR2rl8dGkwg