Earth's Rotation Speed Is Increasing

On 9 July 2025, Earth completed a full rotation 1.6 milliseconds faster than the standard 24-hour day. This was the shortest day ever recorded, indicating a sudden increase in Earth's rotation speed.

This unusual event is of great scientific importance and a key topic for SSC exam preparation, especially in the general awareness and science sections.

What Is Earth's Rotation Speed?

Earth's rotation speed refers to how fast the planet spins around its axis. At the equator, the average rotation speed is about 1,670 km/h. This speed influences:

• The length of a day

• Timekeeping systems (like UTC)

• Weather patterns

• Ocean tides

• Satellite navigation

When Earth spins faster, the day lengthens. The recent change in Earth's rotation speed has implications for global time synchronization.

Why Did Earth Spin Faster in July 2025?

Scientists say the gravitational influence of the Moon played a major role. The Moon’s tidal forces pull on Earth's surface, affecting the spin speed variation. Other factors influencing Earth's rotation speed include:

• Seismic activity and tectonic movements

• Changes in atmospheric pressure

• The melting of glaciers, which redistributes Earth’s mass

• Ocean currents and wind patterns

These dynamic factors together cause slight but measurable changes in Earth’s angular momentum and equatorial rotation speed.

Important Dates with Shorter Days

After 9 July 2025, scientists observed similarly shorter days on:

• 22 July 2025

• 5 August 2025

These patterns suggest a temporary but notable acceleration in Earth's rotation speed. Continuous tracking is essential to understand whether this is part of a cyclical shift or a long-term trend.

How Does Earth's Rotation Speed Affect Timekeeping?

Modern timekeeping is based on two scales:

• UTC (Coordinated Universal Time) – Based on atomic clocks

• UT1 (Universal Time 1) – Based on Earth's rotation speed

When Earth’s spin rate deviates, leap seconds are added or removed to align the two. So far:

• 27 positive leap seconds have been added since 1972 due to Earth slowing down.

• A negative leap second (to remove 1 second) is now planned for 2029, a first in human history, due to increased Earth rotation speed.

This adjustment is crucial to keep astronomical and atomic time in harmony.

Key Scientific Terms SSC Aspirants Should Know

• Earth’s axis: The imaginary line around which Earth rotates

• Day length: The Time Earth takes to complete one full spin

• Earth rotation time: Varies slightly due to natural forces

• Planet rotation: The spinning of Earth around its axis

• Atomic time: Time measured by highly accurate atomic clocks

• Astronomical time: Time based on the actual Earth rotation speed

Does Faster Rotation Affect Daily Life?

Currently, no significant effects are felt by humans due to this increased Earth rotation speed, but the scientific community is watching closely. Key concerns include:

• Impact on GPS accuracy

• Satellite alignment

• Astronomical observations

• Data transmission timing

How Do Scientists Measure Earth Rotation Speed?

They use tools like:

• Very Long Baseline Interferometry (VLBI)

• Laser gyroscopes

• Global Positioning System (GPS) data

• Satellite laser ranging

These instruments detect even microsecond-level changes in Earth's rotation speed, helping experts forecast future events like leap second needs.

Must-Know SSC Questions

1. What was the shortest day recorded and when?
   → 9 July 2025, shorter by 1.6 milliseconds

2. What causes changes in Earth’s rotation speed?
   → Tidal forces, seismic shifts, glacial melting, and atmospheric patterns

3. What is the impact of a negative leap second?
   → One second will be removed from UTC to correct for the faster Earth's rotation speed

4. How fast is the Earth rotating right now?
   → Approx. 1,670 km/h at the equator, slightly faster than before

5. What is the difference between Earth’s orbit and rotation?
   → Rotation is spinning around its axis (24 hrs); Orbit is revolution around the Sun (365 days)

Final Thoughts

The recent acceleration in Earth's rotation speed is a rare but significant event with wide implications for timekeeping, navigation, and scientific research. The shortening of the day on 9 July 2025 shows how sensitive our planet is to natural forces like the Moon’s gravity.

With the announcement of a negative leap second in 2029, timekeeping systems must adjust to remain accurate. Understanding these changes helps scientists improve models of Earth’s dynamics.

For SSC aspirants, this topic is highly relevant across the science and current affairs sections. Stay updated, as questions on Earth's rotation speed may likely appear in upcoming exams.