Thanks! This is updated now, and you should be able to access the website https://hengefinder.rcdis.co/ on mobile. You can also download the app with more features at https://hengefinder.com/

Smartphones have the huge advantage of direction sensors (3D magnetometer and gyro). I remember using apps like Google sky map (or something like that) way back in 2011 to look at satellites and planets.

There's a mobile app that supposedly works worldwide (but isn't available in my country).

Really wish mobile browsers were better liars when it comes to "desktop mode"

There’s a few sites that do what I think you’re asking for, not navigation though. This is one I’ve used recently: https://shademap.app/

This is exactly what I am working on for my city (Berlin). Right now it gives you sun/shade times for outside areas of cafes and restaurants as well as heatmaps for public parks and playgrounds.

The idea is to eventually offer a sun or shadow mode and the app will then surface areas, squares, and streets with more sun or shade and eventually offer walking and biking routes with more or less sun.

This could also be a legitimate lifesaver in places like India where extreme heat is common but delivery and gig workers have to travel outdoors.

Update: I just vibe coded myself one, gave me an excuse to play with Antigravity (and then cleaned up/improved with Claude Code). Not posting a link yet because it serves 12MB worth of geo JSON up to the client on first page load, and I'm not eager to wake up tomorrow with a bill for upload traffic spike. But it pretty much does its job as well as it could given quality of available data (OSM), so now I'm looking at improving the data itself.

It currently runs A* for routing between two points on map (no address lookups yet), using either local A* or an OSMR endpoint for base path, and then A* for shadow-aware routing, and shows both, + stats (total time exposed, how much it saves in sunlight exposure and loses in time relative to base), plus has a bunch of debugging overlays so I can validate and diagnose pathfinding and data quality. But I tested it live today, and it mostly checks out with reality (big gap: no data on trees).

Any angle within 23º of east-west will have henging at some time of year. You'd have to have the entire street grid be aligned diagonal rather than cardinal.

Living in the US Midwest, there are lots of towns that are laid out on north-south grids, including portions of mine. As a cyclist, I take note of the days when the sun is coming up over east-west streets, because the car drivers can barely see where they're going. I once saw a multi-car crash on my own street (fortunately at very low speed) that I attributed to this effect.

Additionally I have visited Stonehenge and it's sterilised and disappointing being unable to walk amongst the stones. Thank you for your attention to this matter.

Hello, thank you! That option already exists: On the website version, it's available in the "Henge Near Me" tab. You can toggle between Sunrise and Sunset.

There are more features on the mobile version, and it also includes Sunrise and Sunset. Just hit the gear icon on the top right, and toggle between Sunrise and Sunset. Hope that helps!

Apparently the word "henge" comes from the name Stonehenge but Stonehenge has the ditch on the wrong side of the bank to technically be a henge.

For any other curious people: https://www.english-heritage.org.uk/visit/inspire-me/what-is...

then use a stick™

hint, watch the sticks shadow

other hint, can use almost anything that casts a shadow, as a stick substitute.

* even more hints availible with stick™ pro

Thanks for flagging! This should be fixed now.

Any sufficiently small section of the street is indistinguishable from a straight street.

Yep, if I use street name it attaches to wrong part of the street, if I use a place next to the street it attaches to the place, not the street. Couldn't figure out how to drag the origin point of the arrow

The sun?

Hi, thank you! The feature to add to your calendar exists!

In the mobile app: long tap on map to drop the pin + alignment arrow. Move the arrow to the line of the road. The "Henge Information" panel slides up from the bottom and has an option to export the henge date to the calendar.

If you're using the website version: it's in the "find a henge" tab. Once the henge is found, you hit "Add to Calendar"

it’s nuts that more streets in manhattan aren’t pedestrianized