Wednesday, 9 July could have been the shortest day of your life – literally.
Earth’s rotation has been accelerating, and this week’s date is among several projected to be fractions of a millisecond shorter than usual.
Atomic clock measurements show that 9 July, 22 July and 5 August are expected to be between 1.3 and 1.51 milliseconds shorter than the standard 24-hour day – an unusual but increasingly frequent phenomenon.
The shortest day on record occurred on 5 July 2024, when Earth completed its rotation 1.66 milliseconds faster than the standard solar day of 86 400 seconds.
Why is Earth spinning faster?
While the cause isn’t fully understood, scientists say the acceleration could be influenced by several natural forces:
- Melting glaciers, shifting mass away from the poles
- Changes in atmospheric pressure and wind patterns
- Motion in Earth’s molten core
- A weakening magnetic field
According to Graham Jones, an astrophysicist at the University of London, and data from the US Naval Observatory, the Earth’s Length of Day (LOD) is being monitored to millisecond accuracy by atomic clocks, which track the vibrations of atoms to keep time.
“Earth’s spin is like a figure skater – when mass is pulled in, it spins faster,” explained Richard Holme, a geophysicist at the University of Liverpool.
Seasonal changes in mass distribution – like trees leafing out during northern summers – can also subtly shift the planet’s rotational balance.
Why it matters
Although these time differences are imperceptible to humans, they have critical implications for:
- GPS navigation systems
- Telecommunications
- Financial transaction timing
- Satellite operations
Tiny time discrepancies can lead to technical glitches in highly synchronised systems.
From leap seconds to negative time?
Traditionally, scientists adjust for Earth’s slower spin by occasionally adding a leap second to Coordinated Universal Time (UTC).
But if Earth’s faster spin continues, we may eventually need to remove a second – creating a “negative leap second” for the first time in history.
The moon’s long-term effect
Ironically, while Earth’s spin has sped up in recent years, long-term trends predict the opposite.
The moon’s gravitational pull is slowly causing Earth to spin more slowly.
According to geoscientist Stephen Meyers, Earth days could stretch to 25 hours – but not for another 200 million years.
Did you notice your time felt rushed on Wednesday, 9 July … ?
Let us know by leaving a comment below, or send a WhatsApp to 060 011 021 1
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