The Earth's rotation is the rotation of the solid earth around its own axis, which is called Earth's axis or rotation axis.

Rotation period

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The average rotation period of the Earth is called "sidereal day". Its value is 23 h 56 m 4.091 s and describes the rotation with respect to the cosmic background of the stars. In contrast to this, the rotation with respect to the Sun is 24 hours, because we are revolving around the sun once per year. Per day the difference is
86 400 s / 365.25 = 236 seconds = 3 m 56 s (as can be seen above).

This must not be confused with the length of day (abbrev. LOD), which the IERS defines as the difference between the astronomically determined duration of the day (relative to the Sun) and 86,400 SI seconds.Universal Time (UT1) and Length of Day (LOD)

References

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External links

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• Weather Makes Earth Wobble - the first study to demonstrate that day-to-day changes in atmospheric pressure produce a measurable effect on Earth's rotation.

Celestial mechanics