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

Adding: The two paths respectively are about 80% and 28% of the earth's circumference.

Kudos to whoever built tiled clouds background on the gcmap site.

I opened Apple Maps in globe mode and I still have trouble visualizing the water path.

The Portugal to (approximately) Macao one is quite interesting, thanks for the links!

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

It seems like that path crosses the Suez canal. I think it's fair that bridges and/or tunnels don't count.

If you are talking about the trail from Cape Town to Vladivostok, that one is not a straight line.

That would an interesting finding!

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.

> 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.

This is mathematics, the Alps is drivable like a manifold is smooth.

Presume for a moment that you don’t drive on tyres…

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.

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.

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 ;-)

It would be a straight line (in their official map) from the south of Portugal to Kamchatka (east Russia)

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.

“Drive”.

Use your feet, car centric person.

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...