Antipode Calculator (Opposite Point on Earth)

Two accidents of geography compound: 71% of Earth is ocean to begin with, and the continents are arranged 'antipodally unlucky' — the Pacific Ocean (a third of the planet's surface) sits opposite nearly all of Africa, Europe and Asia's land. Run the overlap and only ~15% of land faces land. The respectable exceptions: much of South America pairs with East/Southeast Asia, New Zealand with Iberia, and parts of Indonesia with the Amazon basin.

Exactly — and uniquely: every great circle through your position passes through your antipode, so the distance is half the circumference (~20,015 km) in every direction at once. This has a navigational quirk: from anywhere, ALL bearings lead to your antipode in the same distance — there's no 'shortest direction.' It's also why antipodal city pairs (Auckland↔Seville at ~19,800 km) define the practical maximum for direct flights: beyond-antipodal routes don't exist.

Seasons, yes by geometry: hemisphere flips, so a Madrid June pairs with a Wellington winter. Day and night invert approximately (longitude shifts 180°, so solar time differs by ~12 hours), but CIVIL time zones follow politics — Madrid↔Wellington differ by 10–11 clock hours depending on daylight saving, not 12. The folklore that antipodes have 'opposite everything' is solid for sun geometry, fuzzy for clocks, and famously wrong for toilets (Coriolis at drain scale is negligible — basin shape decides the swirl).

The classic physics-class fantasy: through a frictionless, airless tunnel via the centre, gravity weakens linearly with depth (only the mass beneath you pulls), giving simple harmonic motion — you'd surface at the antipode in about 42 minutes, momentarily at rest, then fall back. The marvelous footnote: ANY straight chord tunnel between two points takes the same ~42 minutes under ideal assumptions. Reality declines: 6,000 °C core, 360 GPa pressure, and the tunnel is geophysically impossible — which is why this calculator and not a shovel.