My Science School

 

          The Moon has a dark side. Don’t worry; we are not talking about anything evil here. The side that faces away from the Earth is known as the Moon’s dark side. This is because of the shape of the lunar orbit.

          We know that the lunar orbit is elliptical. As a result, the Moon travels at different speeds at different points. Because of this, we can see more than half of the Moon’s surface. This phenomenon is known as libration. About 59 per cent of the Moon’s surface is visible from the Earth because of this phenomenon. Johannes Hevelius studied librations in detail and published his findings in 1647. His work was titled Selenographia.'

Picture Credit : Google

 

          Many planets in the solar system have natural satellites. But Earth and its natural satellite share a special relationship.

          The Moon is Earth’s only natural satellite. Though our Moon is small when compared to the moons of Jupiter or Saturn, its size in relation to that of Earth is quite large.

          Along with revolving around the Earth, the Moon also revolves around the Sun in sync with the Earth. They look more like two sister planets than a planet and its satellite.

          Therefore, together, the Earth and the Moon are considered as a double planetary system.

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          The Moon has a near side and a far side. The side that permanently faces the Earth is known as the near side while the side that faces away is known as the far side. Though these sides are so, the amount of sunlight they receive is almost the same.

          The surface of the near side differs from the far side; the near side is covered by large patches of dark areas. Early scientists proposed that these dark areas were seas with water. The dark patches are still known as seas. The far side does not have such seas. The crust here is thicker than the side facing the Earth.

Picture Credit : Google

 

 

          The Earth takes 24 hours to complete one rotation. But the Moon’s rotation is not that short; it takes 27 days, 7 hours and 43 minutes for the Moon to complete one rotation.

          The Moon’s axis is similar to that of the Earth; it is tilted towards one side. The Moon completes one round in its orbit around the Earth in almost the same time taken for one spin.

          Since the time taken for both movements are the same, the Moon always keeps the same side facing the Earth. This means that we get to see only one side of the Moon.

Picture Credit : Google