What alters the length of a day?

Researchers have found that periodic jumps generated in the earth’s core change the length of a day every 5.9 years on our planet. They found that variations in the length of the day over periods of between one and ten years are caused by processes in the Earth’s core. The Earth rotates once per day, but the length of this day varies.
A year 300 million years ago would have lasted for about 250 days and a day would have lasted for about 21 hours. Hence, the Earth’s six-year twitch alters the length of the day.

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At what rate does the earth spin?

The earth spins or rotates on its axis every day. It takes 24 hours to rotate once on its axis. To calculate the rate of rotation, the circumference of the earth at the equator, which is 25,000 miles, is divided by the total time taken per rotation, which is 24 hours. The value comes to be approximately 1,000 miles per hour or 1,600 km per hour, which is equivalent to covering the distance between Delhi and Mumbai in 52 minutes (approx.)—quite a high speed indeed.

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