The equator is not the halfway point
Play a journey back and the line works its way down the map. At some point it crosses the equator, and nothing on screen marks the moment. We took all 89 cities in the southern hemisphere out of our 524 and worked out exactly where the line from Seoul passes latitude zero.
No crossing can happen closer than 4,177km
Seoul sits at 37.5665°N. Head due south to the equator and that is 4,177km. There is no equator point nearer than that. The earliest crossing we actually found belongs to the route to Dili, which reaches latitude zero 4,179km out of Seoul — two kilometres off the theoretical floor.
The number does not shrink no matter how near or far the destination is. Every journey into the southern hemisphere runs at least 4,177km before it meets the equator.
Some cross at 25.4%, some at 99.8%
| Destination | Total distance | To the equator | Share of the route |
|---|---|---|---|
| Ushuaia | 17,777km | 4,515km | 25.4% |
| Sydney | 8,329km | 4,384km | 52.6% |
| Cape Town | 13,714km | 7,378km | 53.8% |
| Bali | 5,257km | 4,299km | 81.8% |
| Rio de Janeiro | 18,133km | 15,295km | 84.3% |
| Nairobi | 10,109km | 9,873km | 97.7% |
| Quito | 15,107km | 15,084km | 99.8% |
The route to Ushuaia is 17,777km long and enters the southern hemisphere a quarter of the way in, then spends the remaining 13,000km below the line. Quito is the opposite case: it crosses 23km before arrival, because Quito sits at 0.18°S.
It is tempting to picture the equator as a turning point, but where the line crosses it is set by the latitude of the destination. Nor does the crossing move later as the trip gets longer. Bali crosses at 81.8% of a 5,257km route; Sydney crosses at 52.6% of an 8,329km one. Measured from Seoul those two points are 4,299km and 4,384km out — 85km apart.
Seventy-one of the 89 cross over water
Split the crossing points into land and sea and 71 of them are at sea. Here is what lies under the other 18.
| Country | Destinations crossing above it |
|---|---|
| Indonesia | 5 |
| Ecuador | 4 |
| Brazil | 4 |
| Colombia · DR Congo · Somalia · Uganda · Kenya | 1 each |
The interesting part is that the country under the crossing is usually not the destination's country. The line to Arusha in Tanzania crosses over Somalia; the line to Kigali in Rwanda crosses over Uganda. The lines to Uyuni and La Paz in Bolivia and to Puno in Peru all cross over Ecuador, because that is where a route heading down the western side of South America first touches the continent after the Pacific.
The crossing longitudes are spread from 174.5°W to 177.3°E, which is very nearly the whole equator. A great circle is the ring where a plane through the centre of the Earth meets the surface, and the two points that fix that plane are the origin and the destination. It meets the equator in exactly two places; which of them a route uses is decided by where it is going.
The screen never mentions it
The service does not draw the equator. There are no parallels and no borders either. What plays back is an interpolated great circle and a set of city names, so the moment of crossing into the southern hemisphere goes by unremarked.
Of the 84 recommended destinations, 27 are in the southern hemisphere. Pick one of those and the line will certainly pass through somewhere in the table above. Usually it is open water with nothing marked on it.