alt.hn

5/22/2026 at 8:39:42 PM

Hengefinder: Finding when the sun aligns with your street

 https://victoriaritvo.com/blog/hengefinder/

by evakhoury

5/23/2026 at 6:02:56 PM

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

by lefra

5/23/2026 at 6:28:42 PM

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.

by HPsquared

5/24/2026 at 6:41:58 AM

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

by AkshatJ27

5/23/2026 at 9:12:07 PM

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

by jeroenhd

5/23/2026 at 11:30:43 PM

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

by russdill

5/24/2026 at 2:41:49 AM

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

by cholmdomsky

5/24/2026 at 2:18:42 AM

[dead]

by foofyter

5/23/2026 at 10:58:09 PM

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.

by TeMPOraL

5/24/2026 at 1:01:54 AM

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/

by abejfehr

5/24/2026 at 7:52:36 AM

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.

by josters

5/24/2026 at 5:26:30 AM

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.

by waterproof

5/24/2026 at 1:34:47 AM

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...

by infinet

5/23/2026 at 6:58:20 PM

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.

by pierrec

5/24/2026 at 8:06:04 AM

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

by tcumulus

5/23/2026 at 7:13:46 PM

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.

by normie3000

5/24/2026 at 1:48:36 PM

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.

by analog31

5/23/2026 at 10:53:07 PM

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.

by vikingerik

5/23/2026 at 7:15:08 PM

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.

by normie3000

5/23/2026 at 9:58:14 PM

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.

by petargyurov

5/23/2026 at 6:03:24 PM

Stonehenge of course, famously not a henge.

by 4ndrewl

5/23/2026 at 7:04:59 PM

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...

by tdb7893

5/23/2026 at 7:44:35 PM

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

by 4ndrewl

5/23/2026 at 5:54:33 PM

Mobile app not available in your country. :(

by donalhunt

5/23/2026 at 6:23:10 PM

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

by metalman

5/23/2026 at 6:38:49 PM

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.

by sonofhans

5/24/2026 at 10:31:29 AM

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.

by metalman

5/23/2026 at 10:14:05 PM

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.

by donfuzius

5/23/2026 at 6:51:47 PM

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

by thisisauserid

5/23/2026 at 6:55:46 PM

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

by idbnstra

5/24/2026 at 6:12:32 AM

this is true

by gregjw

5/23/2026 at 9:17:26 PM

It doesn't work with curved streets.

by nephihaha

5/23/2026 at 9:52:40 PM

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

by nkrisc

5/23/2026 at 10:55:40 PM

Tell that to all the buildings blocking the light

by pimlottc

5/24/2026 at 7:53:18 AM

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

by bayesianbot

5/23/2026 at 9:25:17 PM

The sun?

by jrflowers

5/23/2026 at 6:28:18 PM

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.

by fuzzfactor