Does the earth rotate completely on new year day

What a great question!

The Earth's rotation is not perfectly uniform, and it's not exactly true that the Earth rotates completely on New Year's Day. Here's why:

  1. Earth's rotation is not a perfect circle: The Earth's rotation is slightly elliptical, which means its axis is not perfectly perpendicular to its orbit around the Sun. This elliptical shape causes the planet to wobble slightly, which affects the timing of its rotation.
  2. Tidal interactions: The gravitational pull of the Moon and Sun on the Earth causes a slight slowing down of the planet's rotation. This effect is more pronounced during the full moon and new moon phases, when the gravitational forces are stronger.
  3. Atmospheric and oceanic circulation: The movement of air and water in the atmosphere and oceans also affects the Earth's rotation. For example, the jet stream and ocean currents can transfer angular momentum from one part of the planet to another, causing the rotation to slow down or speed up slightly.
  4. Earth's slightly irregular shape: The Earth is not a perfect sphere, but rather an oblate spheroid (flattened at the poles and bulging at the equator). This irregular shape also affects the planet's rotation.

As a result of these factors, the Earth's rotation is not perfectly uniform, and it doesn't rotate exactly 24 hours on New Year's Day. In fact, the length of a day on Earth varies by about 1.78 milliseconds over the course of a year due to the gravitational pull of the Moon and Sun.

So, while the Earth does rotate on New Year's Day, it's not a perfect, uniform rotation. The planet's rotation is influenced by various factors, which cause it to wobble and slow down or speed up slightly over time.