Great-Circle Paths
Why flights look curved on flat maps.
London to Tokyo is 9,559 km on a great circle, and the shortest path arcs up close to the Arctic. On a flat map that route looks like an absurd detour north; on a globe it is a straight line, and it is the reason so many Europe to Asia flights cross at high latitude. The longest pair drawn here, New York City to Sydney, runs 15,989 km, roughly 18 hours at a 900 km/h cruise. A great circle is simply the intersection of the sphere with a plane through its centre, which is why it is always the shortest surface route between two points and why no flat map can draw it straight everywhere at once.
From: London (GB)
To: Tokyo (JP)
That curve IS the straight line: the shortest path on a sphere only looks bent on flat maps.
Distance
9,559 km
great-circle, computed
Flight time
11h 07m
ESTIMATE: 900 km/h cruise + 30 min, not a schedule
Time difference
-
current IANA offsets (London vs Tokyo)
Time zones crossed is not shown: the open boundary dataset was deferred as too heavy (see DATA_GAPS.md), and we do not fabricate it.
Cities and time zones: GeoNames (CC BY 4.0). Shapes: Natural Earth (public domain). Time zone rules: IANA via the Intl API.
About this visualization
About this data
Distances are exact spherical great-circle math. The flight time is an ESTIMATE (900 km/h cruise plus 30 minutes) for intuition, not a schedule. The time difference uses each city's IANA zone from GeoNames, evaluated by your browser's timezone rules right now, so daylight saving is always correct. It is the one figure on this page that is not precomputed, precisely because it changes with the season.
Common questions
- Why do flight paths look curved on a map?
- Because the shortest route between two points on a sphere is a great circle, and flattening a sphere onto a rectangle bends those routes. The curve is an artifact of the projection: on a globe the path is perfectly straight.
- Why do flights between Europe and Asia pass near the Arctic?
- Because that genuinely is the shorter way. On a Mercator map a polar route looks like a long detour north, but on a globe it is close to a straight line, which is why many long-haul routes cross at high latitudes.
- How is the distance calculated?
- As a great-circle distance across the surface of the Earth, treated as a sphere. Real flights are slightly longer because of air traffic routing, winds, and airspace restrictions.
- How far is London from Tokyo?
- 9,559 kilometers on a great circle, which works out at roughly 11 hours in the air at a typical 900 km/h cruising speed plus taxi time. The shortest route passes close to the Arctic rather than across central Asia, which looks wrong on a flat map and is correct on a globe.