Leap Second Watch Screensaver
The Leap Second Watch screensaver shows the real history of every leap second added to civil time since 1972, from the International Earth Rotation and Reference Systems Service. It is free, runs in your browser, and ESC exits.
How the Leap Second Watch screensaver works
The saver displays the real, complete published history of every leap second inserted into UTC since 1972.
A live running clock shows real elapsed time since the most recent leap second.
The record is a real, curated list from the International Earth Rotation and Reference Systems Service's own bulletins.
No live feed is required for the historical record; the clock runs locally.
A worked example
The real gap of several years since the last leap second, reflecting Earth's recently more stable rotation rate, is shown by the live running clock.
Settings & tips
- Accent recolours the running clock.
- Every date is a real, officially inserted leap second.
- Leap seconds are scheduled irregularly, based on real measured Earth rotation.
Frequently asked questions
- Is this a real historical record?
- Yes — every leap second since 1972, from the official real IERS bulletins.
- Is a key needed?
- No — the record is a curated real list and the clock runs locally.
- Why do leap seconds happen?
- Earth's real rotation is slightly irregular, so leap seconds keep UTC aligned with it.
- Is it free?
- Yes — free, no download, in your browser.