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Time, Calendars, and Seasons

Introduction

Does the Earth always rotate and revolve around the sun at the same speed?

No, the Earth’s revolution around the sun and rotation on its axis are not perfect. Its daily rotation may vary by approximately four to five milliseconds, and is slowing down at a rate of one millisecond each century, due to tidal friction. Additionally, the axis wobbles slightly, and the length of revolution around the sun varies by a few milliseconds.