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Comment by ventana | original | Longest Straight Line Paths on Water or Land on the Earth (2018)
[−]ventana · 2026-08-30 Sun 08:44 UTC · link
The paper is basically like this (spoiler alert):

“Some random user on Reddit posted a picture claiming that this is the longest straight line path on water possible on the Earth. We implemented a smart algorithm to solve this problem, found the elevation data, ran our algorithm... yes, that random user was right. Also, here's the longest path on land.”

Thanks, I really enjoyed reading it, even though I hoped that they would disprove the original claim!

Edit: here are the gcmap links to the two paths: sea [1], land [2].

[1]: http://www.gcmap.com/mapui?P=25%B017%27N+66%B040%27E-58%B037...

[2]: http://www.gcmap.com/mapui?P=24%B033%27N+118%B038%27E-37%B02...

[−]comrade1234 · 2026-08-30 Sun 10:12 UTC · link
I opened Apple Maps in globe mode and I still have trouble visualizing the water path.
[−]pdpi · 2026-08-30 Sun 10:38 UTC · link
Does it help to point out that the water path looks suspiciously like the day/night line on a map?

Like this: https://svs.gsfc.nasa.gov/5477/

[−]newtwentysix · 2026-08-30 Sun 12:28 UTC · link
yes!! why is that ? :)
[−]yorwba · 2026-08-30 Sun 13:01 UTC · link
The day/light line is a great circle. The "straight line paths" are great-circle segments.
[−]srean · 2026-08-30 Sun 12:44 UTC · link
It's going South and then trying to close the loop from behind. It gets interrupted by land before the loop closes.

Hope it makes sense.

[−]turbocon · 2026-08-30 Sun 12:53 UTC · link
Open the linked paper and scroll down, they have images of the path on a globe as well as the flat map view.
[−]cubefox · 2026-08-30 Sun 11:13 UTC · link
They only identify the Reddit user as "kepleronlyknows", but in the Reddit thread [1] he links to his video visualization [2], where his user name is Patrick Anderson.

Before he made the video visualization using Google Earth, he actually went to the library and used a string on a real globe. [3]

1: https://www.reddit.com/r/MapPorn/comments/15mwai/the_longest...

2: http://www.youtube.com/watch?v=VpQwuGueeoA

3: https://imgur.com/a/great-circle-2hYFM

[−]alok-g · 2026-08-30 Sun 16:28 UTC · link
Adding: The two paths respectively are about 80% and 28% of the earth's circumference.
[−]kromokromo · 2026-08-30 Sun 16:29 UTC · link
Kudos to whoever built tiled clouds background on the gcmap site.