Hengefinder: Finding when the sun aligns with your street (opens in new tab)

(victoriaritvo.com)

166 pointsevakhoury2d ago37 comments

37 comments

I need the inverse of that - an app that predicts how badly a given street will be baked by the sun at current or near-future time, will there be any shadow zone from the buildings, how far will the usable extent of it reach (e.g. not much use of shadow if my head or body stick up beyond the shaded volume). Ideally available on a smartphone. Bonus points for being able to route navigation paths to minimize direct sun exposure.

Motivation: I hate it when it's hot, but my kid has actual issues with heat/sun exposure, and e.g. I had to navigate our way around the city through shaded zones today, just so she doesn't get exhausted in under 30 minutes.

Plenty similar apps are made to sell people photovoltaics, but I'd love to see something to help humans avoid sun.

TeMPOraL16h ago

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).

abejfehr1d ago

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/

josters1d ago

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.

waterproof1d ago

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.

lefra1d ago

It would be nice to be able to access the website on a smartphone (even if the experience is suboptimal), instead of denying access.

HPsquared1d ago

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.

AkshatJ271d ago

Not sure if this is the app you were referring to, But Stellarium does exactly what you're describing.

jeroenhd1d ago

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

russdill1d ago

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

cholmdomsky1d ago

Seriously. Plus, what is the problem that some websites are 'fixing' by denying me a choice in how the website loads?

infinet1d ago

It uses the Python lib Astral, which uses "equations from Astronomical Algorithms, by Jean Meeus", to find location of the Sun in the sky. That method assuming earth motion without gravitational pull from other planets or the Moon, and has accuracy of 0.01 arc degree. Meeus is a rock star in these kinds of calculations. He also gave a truncted version of VSOP87 that has error less than 1 arc second in finding Sun's location.

The method Astral uses for calculate Moon's location has precision of 1 arc minute. For higher precision, LEA-406 [1] can be used.

[1] https://www.aanda.org/articles/aa/full/2007/33/aa7568-07/aa7...

pierrec1d ago

Interesting, I've planned similar shots before and used different tools that serve a similar purpose. The Photographer’s Ephemeris has nice visualizations: https://photoephemeris.com/

NASA's Horizons ephemeris is also pretty good at preparing data for this. I've used it with a little script to check when the sun/moon will be in a given box. This hengefinder looks neat and really streamlined for its purpose though.

tcumulus1d ago

Very interesting, but sounds like an extra complication to use binary search on time to find the right position of the sun, when you can just directly calculate this, eg. using the formulas in here: https://gml.noaa.gov/grad/solcalc/solareqns.PDF

jcynix1d ago

Various apps for (primarily) photographers offer views of the sun's (and moon's) path, even with live view through the camera.

For example https://www.sunsurveyor.com/ or https://www.photopills.com/ best among others

normie30001d ago

I lived a long time in a city near the equator with a prominent east-west street. Commuting west to east in the morning and east to west in the evening meant frequent hengings. The roads don't feel particularly safe when you can't see anything. The town planners might have considered this.

analog311d ago

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.

vikingerik1d ago

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.

normie30001d ago

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.

petargyurov1d ago

On a similar note, for this August's total solar eclipse (in Europe), I 3D modelled the sun's position in the sky from the viewpoint that I am planning to go to. The eclipse will happen late in the day when the sun will be low, so I wanted to make sure that nothing will obstruct my view!

I've been meaning to post about it.

GeoAtreides1d ago

older, better alternative: https://suncalc.net/

donalhunt1d ago

Mobile app not available in your country. :(

metalman1d ago

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

sonofhans1d ago

I’d like to subscribe to stick™ pro! I tried a piece of string and it waved around in the wind and didn’t work, so I think I may need a paid service for this.

metalman1d ago

your in luck due to a need to redirect our efforts we are opensourcing, stick™ and stick pro, under the historic source code "anelemma" which is stick™ plus rocks™

instruction manual:place stick verticaly on planet. observe shadow™ and place rock™ at point of of maximum shadow length, each day continue untill the pattern starts to repeat. reverse engineer orbital dynamics and gravitational atraction from resulting pattern. scratch head. build civilisation.

4ndrewl1d ago

Stonehenge of course, famously not a henge.

tdb78931d ago

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...

4ndrewl1d ago

Ye - also the henge is the circular ditch, not the stone circle or whatever in the centre

donfuzius1d ago

Nice, and awesome that it works internationally. One little feature request: provide an .ics download, so that I can add a calendar event, add a link to the original calculation to the the calendar entry.

thisisauserid1d ago

Manhattanhenge is cool but people standing in the middle of street for it is pretty nuts.

idbnstra1d ago

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

gregjw1d ago

this is true

nephihaha1d ago

It doesn't work with curved streets.

nkrisc1d ago

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

pimlottc1d ago

Tell that to all the buildings blocking the light

bayesianbot1d ago

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

jrflowers1d ago

The sun?

fuzzfactor1d ago

It would be good to also have the option for alignment with sunrises in addition to sunsets.

For instance in Houston the sunrise aligns with Texas Avenue around the June solstice.

Consequently, there are no sunset alignments for the downtown skyscrapers.

j / k navigate · click thread line to collapse

37 comments

TeMPOraL1d ago

Plenty similar apps are made to sell people photovoltaics, but I'd love to see something to help humans avoid sun.

TeMPOraL16h ago

abejfehr1d ago

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/

josters1d ago

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.

waterproof1d ago

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.

lefra1d ago

It would be nice to be able to access the website on a smartphone (even if the experience is suboptimal), instead of denying access.

HPsquared1d ago

AkshatJ271d ago

Not sure if this is the app you were referring to, But Stellarium does exactly what you're describing.

jeroenhd1d ago

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

russdill1d ago

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

cholmdomsky1d ago

Seriously. Plus, what is the problem that some websites are 'fixing' by denying me a choice in how the website loads?

infinet1d ago

The method Astral uses for calculate Moon's location has precision of 1 arc minute. For higher precision, LEA-406 [1] can be used.

[1] https://www.aanda.org/articles/aa/full/2007/33/aa7568-07/aa7...

pierrec1d ago

Interesting, I've planned similar shots before and used different tools that serve a similar purpose. The Photographer’s Ephemeris has nice visualizations: https://photoephemeris.com/

tcumulus1d ago

jcynix1d ago

Various apps for (primarily) photographers offer views of the sun's (and moon's) path, even with live view through the camera.

For example https://www.sunsurveyor.com/ or https://www.photopills.com/ best among others

normie30001d ago

analog311d ago

vikingerik1d ago

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.

normie30001d ago

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.

petargyurov1d ago

I've been meaning to post about it.

GeoAtreides1d ago

older, better alternative: https://suncalc.net/

donalhunt1d ago

Mobile app not available in your country. :(

metalman1d ago

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

sonofhans1d ago

I’d like to subscribe to stick™ pro! I tried a piece of string and it waved around in the wind and didn’t work, so I think I may need a paid service for this.

metalman1d ago

your in luck due to a need to redirect our efforts we are opensourcing, stick™ and stick pro, under the historic source code "anelemma" which is stick™ plus rocks™

4ndrewl1d ago

Stonehenge of course, famously not a henge.

tdb78931d ago

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...

4ndrewl1d ago

Ye - also the henge is the circular ditch, not the stone circle or whatever in the centre

donfuzius1d ago

thisisauserid1d ago

Manhattanhenge is cool but people standing in the middle of street for it is pretty nuts.

idbnstra1d ago

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

gregjw1d ago

this is true

nephihaha1d ago

It doesn't work with curved streets.

nkrisc1d ago

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

pimlottc1d ago

Tell that to all the buildings blocking the light

bayesianbot1d ago

jrflowers1d ago

The sun?

fuzzfactor1d ago

It would be good to also have the option for alignment with sunrises in addition to sunsets.

For instance in Houston the sunrise aligns with Texas Avenue around the June solstice.

Consequently, there are no sunset alignments for the downtown skyscrapers.

j / k navigate · click thread line to collapse