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  • it would be interesting if it was a list of actual journeys with the sub lists of deviations required. a special club for the brutaly determined and persistant the "strait liners" things like having to beg, bluff, bribe, your way through someones house
    by metalman
  • Wikipedia has an article listing some of the notable (walking) straight line missions: https://en.wikipedia.org/wiki/Straight_line_mission

    edit: and the article already notes this longest possible path from Portugal to China, citing a 2023 article: https://bigthink.com/strange-maps/these-are-the-worlds-longe...

    by shrx
  • A new challenge for GeoWizard [1]? :D

    [1]: https://www.youtube.com/geowizard

    by cookie0
  • Before I opened the solution, I knew it had to pass through the beagle straight. It is the only choke point separating the largest oceans, about both their empties areas, the far south.

    I guess my biggest surprise is that there is a straight line through the Beagle straight.

    by rotringlvr
  • Beagle Channel is very narrow and has islands both on the north and the south. This path goes thought the Drake Passage that is south of the islands that are south of the Beagle Channel. The Drake Passage is very wide.
    by gus_massa
  • This geographic puzzle feels like the modern day version of the Seven Bridges of Königsberg:

    https://en.wikipedia.org/wiki/Seven_Bridges_of_Königsberg

    by divbzero
  • But what would flat-earthers consider the longest possible paths to be? Not the ones shown in the article, presumably?
    by 1313ed01
  • It would be a straight line (in their official map) from the south of Portugal to Kamchatka (east Russia)
    by Anduia
  • They would tell us we are contradicting ourselves because none of them are straight lines in the traditional sense, if we really believe the Earth is a sphere. Don't underestimate trolls ;-)
    by astrobe_
  • Over water, probably something like the entire 60th parallel south.

    Over land, I think you want to start near the westernmost point of the African continent and thread the needle of the Isthmus of Suez, and stay south of the Caspian Sea. At least in the projection gcmap.com uses (plate carree - essentially the x-coordinate and y-coordinate are just raw longitude and latitude), this keeps you south of Lake Baikal and allows you to get very far east in far eastern Russia. Something like 17.5 N, 16 W to 69 N, 178.5 E seems to work:

    http://www.gcmap.com/mapui?P=17.5n16w-21.79n0.21e-26.08n16.4...

    Of course this depends on the projection you use!

    This is different from the Portugal-to-China path that is the longest over land in reality, which a flat-earther would have crossing the Mediterranean.

    by madcaptenor
  • > Figure 9: Longest Drivable Straight Line Path on Earth.

    Walkable, maybe, but definitely not drivable (it crosses directly over the Alps, for example).

    by shrx
  • There might be icebergs or sandbars or rocks or volcanic activity or wars blocking the sailing route too. They seem like equivalents.

    The longest mettled straight route with minimal deviation would also be an interesting exercise.

    by pbhjpbhj
  • This is mathematics, the Alps is drivable like a manifold is smooth.
    by chabska
  • Presume for a moment that you don’t drive on tyres…
    by mikeaskew4
  • It reminds me of a bit I did a few years ago trying to find the "longest straightest" line in Atlanta [PDF]: https://matthewritch.com/pages/LongestStraightestLine.pdf
    by mdritch
  • I made a "first person" perspective rendering of this: https://mrgris.com/img/landfall/longest.png
    by mrgriscom
  • I know the globe is unintuitive (it still blows my mind that Muslims in New York City face roughly northeast to point toward Mecca) but it still seems bizarre that the water route can start near the arctic circle, cross the Pacific ocean, nearly touch Antarctica, cross the Atlantic ocean, and cross the Indian ocean to end well north of the equator and still travel only 80% of the way around the globe. This view of the rest of that great circle helped me visualize it: http://www.gcmap.com/mapui?P=58%B037%27N+162%B014%27E-25%B01...
    by gcanyon
  • > it still blows my mind that Muslims in New York City face roughly northeast to point toward Mecca

    It never occurred to me they would face the shortest distance to Mecca. I've looked it up and apparently it's a point of contention in North America, although the great circle seems to be standard. Interestingly there are landmasses around the antipode of Mecca, which means your direction would vary wildly as you travel around.

    by globular-toast
  • If you're in New York and you look due East across the Atlantic, what country are you looking at?

    Most people would assume Portugal.

    Nope, you're looking (over the curve of the earth, of course), at Morocco. Look just a tiny bit to the south and you're looking at the rest of West Africa. Look Southwest and you're looking at Australia, or even Brazil.

    by SamBam
  • There's a longer land path that starts in or near Senegal and ends in China. But they miss it because it goes near the Dead Sea, and they treat anything below sea level as water.
    by OscarCunningham
  • If you are talking about the trail from Cape Town to Vladivostok, that one is not a straight line.
    by Anduia
  • That would an interesting finding!
    by cubefox
  • It seems like that path crosses the Suez canal. I think it's fair that bridges and/or tunnels don't count.
    by khaled_ismaeel
  • Indeed, this route would be about 13,250 km, or about 2,000 km longer than the one TLA suggests.

    http://www.gcmap.com/mapui?P=10%B0+24%27+41.4%22+N,+14%B0+31...

    Or, using nearby airports: https://www.greatcirclemap.com/?routes=gucy-vmmc

    by maratc
  • 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...

    by ventana
  • Kudos to whoever built tiled clouds background on the gcmap site.
    by kromokromo
  • I opened Apple Maps in globe mode and I still have trouble visualizing the water path.
    by comrade1234
  • The Portugal to (approximately) Macao one is quite interesting, thanks for the links!
    by paganel
  • Adding: The two paths respectively are about 80% and 28% of the earth's circumference.
    by alok-g
  • 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

    by cubefox