Which lines of longitude and latitude pass through the most countries? | Hacker News Reader

Which lines of longitude and latitude pass through the most countries?

nwhyte.livejournal.com

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This line passes right on the Delphi, Greece. Known as the center of earth (Ομφαλός της γης), named by the ancient Greek people. coincidence? I think so.

I'm trying to identify exactly what the borders of "the Delphi" are. UNESCO identifies it as "between two towering rocks of Mt. Parnassus". Liakouras is said to be the highest peak of Parnassus - would the Delphi be between there and the second highest peak?

http://whc.unesco.org/en/list/393

Trying to get directions of the Delphi like the ancients is pretty fun there is a 'Maps' link on the page, http://whc.unesco.org/en/list/393/multiple=1&unique_number=4...

I wonder what great circle or small circle passes through the most countries. Looks like a fun optimization problem.

I'm not sure if you have seen this: https://marcinciura.wordpress.com/2015/11/17/slicing-earth-c... — loading country polygons instead of land polygons and changing the LengthOfIntersectionInKm() function should be enough to answer your question. Be wary, however, that parts of France lie in Africa and the Americas (https://en.wikipedia.org/wiki/Overseas_department).

Fun fact: St. Pierre and Miquelon was the site of the only use of the guillotine in North America.

just count the mainland.

Doesn't work for island countries. Think Japan, Philippines, or Indonesia.

then just use the biggest islands.

Then you would ignore 98% of the territory of the Republic of Maldives.

Defining “great circle” gets a bit tricky for an ellipsoid. Geodesics don’t meet back up. https://upload.wikimedia.org/wikipedia/commons/7/77/Long_geo...

I guess you can find the “great ellipse” on a slice passing through the center.

I'm pretty sure that for this purpose, either mapping the earth to a perfect sphere, or using the slice approach (it won't be an ellipse since we're being pedantic) will answer the question.

The latitude/longitude lines in this post were very carefully chosen to just barely knick several countries’ borders and pass over small islands. Differences in the definition of the line certainly will matter for figuring out all of the edge cases here.

not really related, but i wrote this a while back: https://gciruelos.com/what-is-the-roundest-country.html

Kim Jong-un optimising the impact of atomic blasts?

Reminds me of this app. Showing what lies directly across the ocean: https://ranlot.shinyapps.io/coastlinetrip/

Enjoy! http://andywoodruff.com/blog/beyond-the-sea/

That reminds me of this fun question: what is the only U.S. city such that going in all four cardinal directions enters the same neighboring state?

washington Wisconsin?

I had to look it up. This led me to Wikipedia, which identifies no fewer than seven Washingtons in Wisconsin:

https://en.wikipedia.org/wiki/Washington,_Wisconsin

City of New York and the neighboring state being New Jersey?

The southernmost tip of Staten Island works if you count the part of the bay that belongs to NJ.

So Chad and Sudan would be the only countries that are in both lists of countries?

On account of the vastness of the Pacific ocean, there's broad scope for the antipodeal intersection to be outside of any nation state.

Someone (Charles Darwin's son George?) proposed that the Pacific basin was a consequence of the moon being spun off from the Earth, but plate tectonics put an end to that theory.

https://imgur.com/r/Mapporn/QDeiIpc

http://lunarorigin.com/lunar-origin-models/

I didn't realize latitude and longitude lines have width.

They don’t need width for this do they? You could think of them as a set of points which have 0 area, but a region can still contain the points, so which set of points is overlapped by the most regions? I’m pretty sure U’ve got a bad idea there about width.

They don't. But the post has chosen arbitrary "bands" to squeeze more counties in, rather than infinitely thin lines.

I must have missed the bit where he explained why a band of 700m or whatever was optimal

There are infinitely many infinitely thin lines that fit in that band and cover the countries.

Ahh yes, I missed the subtlety that Bulgaria and Slovakia overlapped

All the countries are present throughout the 700m band.

The fine article says:

"In fact there is quite a wide band, between the westernmost point of Bulgaria at 22°31'35.2"E, and the easternmost point of Slovakia at 22°33'32.1", which passes through no less than 26 countries. This is 22 km wide at the equator, but obviously narrows as you get closer to the poles."

yes, I think the idea is that there's an infinite number of infinitely thin lines between 22°31'35.2"E, and 22°33'32.1"

That idea sounds somewhat derivative.

Did I miss the point of this?

That it’s an interesting question?

No. Yours was.

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