hckrnws

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...

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.

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

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.

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.

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.

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.

Stonehenge of course, famously not a henge.

Mobile app not available in your country. :(

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

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.

It doesn't work with curved streets.