---
title: "When did the prime meridian last move?"
description: "The adoption of WGS 84 shifted it about 102 metres east of the Greenwich line, 1984. What happened, and whether it plausibly could happen again."
url: https://atoneplace.net/the-last-time/prime-meridian/
site: "At One Place"
---

# When did the prime meridian last move?

**When did the prime meridian last move?: 1984**

The adoption of WGS 84 shifted it about 102 metres east of the Greenwich line

The brass strip at Greenwich marks the meridian as defined by the Airy transit circle in 1851, and every satellite navigation device places zero longitude about 102 metres to the east of it. The difference is not an error in either: the old meridian was defined relative to local gravity and the vertical as a plumb line finds it, and the new one relative to the Earth's centre of mass. Visitors regularly find their phone disagreeing with the line they are standing on.

- **What:** The adoption of WGS 84 shifted it about 102 metres east of the Greenwich line
- **When:** 1984
- **Category:** Everyday things
- **Could this change?:** Not in any foreseeable way. The event is closed.

## Everyday things

| Question | When |
| --- | --- |
| When did the London Underground last gain a line? | 24 May 2022 |
| When did the tallest building in the world last change? | 2010 |
| When did the Olympics last award medals for art? | 1948 |
| When were the Olympic Games last cancelled? | 1944 |
| When was a leap year last skipped? | 1900 |
| When was a letter last added to the English alphabet? | The 1500s and 1600s |

> This page gives a date and never a "years ago". These pages are built as static files, so a computed interval would freeze at build time and quietly become wrong — which on a reference site is worse than making the reader do the subtraction.

## Common questions

### When did the prime meridian last move?

1984 — The adoption of WGS 84 shifted it about 102 metres east of the Greenwich line.

### What happened?

The brass strip at Greenwich marks the meridian as defined by the Airy transit circle in 1851, and every satellite navigation device places zero longitude about 102 metres to the east of it. The difference is not an error in either: the old meridian was defined relative to local gravity and the vertical as a plumb line finds it, and the new one relative to the Earth's centre of mass. Visitors regularly find their phone disagreeing with the line they are standing on.

## Related pages

- [When did the London Underground last gain a line?](https://atoneplace.net/the-last-time/london-underground-line/)
- [When did the tallest building in the world last change?](https://atoneplace.net/the-last-time/tallest-building/)
- [When did the Olympics last award medals for art?](https://atoneplace.net/the-last-time/olympic-art/)
- [When were the Olympic Games last cancelled?](https://atoneplace.net/the-last-time/olympics-cancelled/)
- [When was a leap year last skipped?](https://atoneplace.net/the-last-time/leap-year-skipped/)
- [When was a letter last added to the English alphabet?](https://atoneplace.net/the-last-time/letter-added-alphabet/)
- [When did analogue television end in the United States?](https://atoneplace.net/the-last-time/analogue-tv-us/)
- [When did the number of planets last change?](https://atoneplace.net/the-last-time/planet-count/)
- [When did Concorde last fly?](https://atoneplace.net/the-last-time/concorde/)
- [When was the US Constitution last amended?](https://atoneplace.net/the-last-time/constitutional-amendment/)
- [When was Halley's Comet last visible?](https://atoneplace.net/the-last-time/halleys-comet/)
- [When was the metre last redefined?](https://atoneplace.net/the-last-time/metre-redefined/)
- [Everything, most recent first](https://atoneplace.net/the-last-time/)

## Sources

- Wikidata — Wikimedia Foundation (https://www.wikidata.org/) [CC0 1.0]