Latitude, longitude and great circles – coordinates and the shortest flight route on a 3D globe
GeographyMaps & MappingAges 15–16
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Sign in to playA 3D globe with a latitude–longitude grid, the Equator, the prime meridian, both tropics and both polar circles, with a Mercator map beside it. Drag two points A and B on the globe or on the map to read their coordinates in degrees and minutes, north/south and east/west. The shortest route is an arc of a great circle, calculated with the haversine formula; it is shorter than the straight line on the Mercator map, which keeps a constant compass bearing. Press Fly to send two planes at the same speed along both routes and see which arrives first.
Lesson: Using maps and digital maps – geographic coordinates, distance on the globe and great-circle routes
What it shows
Every place on Earth has a latitude, measured north or south of the Equator, and a longitude, measured east or west of the prime meridian. The shortest route between two places on a sphere follows a great circle, a circle whose centre is the centre of the Earth. The haversine formula gives its length from the two sets of coordinates. On a Mercator map a straight line keeps a constant compass bearing, but it is usually longer, which is why long-haul flights look curved towards the poles on flat maps.
How to use
Choose a Route, or drag points A and B on the globe or on the Mercator map; hover to read any coordinates. Drag the globe to rotate it and scroll or pinch to zoom. Read the haversine steps, the distance, the take-off bearing and the rhumb-line comparison below. Press Fly to race two planes at the same speed. Change the Grid spacing and tick Special lines or Mercator straight line to show or hide them.
Parameters you can change
- Flight route London – Tokyo, New York – Singapore, Los Angeles – Dubai, Sydney – Santiago, Paris – New York
- Spacing between meridians and parallels 10°, 15°, 30°
- Show the Equator, prime meridian, tropics and polar circles
- Show the straight line on the Mercator map for comparison
Questions to explore
- Why does the London–Tokyo route bulge northwards on the Mercator map?
- When does the straight line on a Mercator map follow the shortest route?
- If two cities share the same latitude, is following that parallel the shortest route?
