Category Man and the Moon

How are tides formed?

          The oceans and seas rise and fall at definite intervals. This rise and fall happens because of the gravitational force between the Earth and the Moon.

          We know that the Moon has a weak gravitational force. But it is strong enough to cause these periodic rises and falls known as tides.

          As our planet rotates, the Moon’s pull is exerted on different parts of the Earth. The Moon’s gravitational force exerts a pull on the oceans that generates tidal energy. It causes both the Earth and the oceans to bulge out in the direction of the Moon and away from it, and is known as tides. Because of the rotation of the Earth around the Sun, two tides occur each day- high tide and low tide.

Picture Credit : Google

 

 

Why is a blue moon called so?

          Will a month have two full moons? Sounds almost impossible. Let’s take a look. The Moon takes almost twenty nine and a half days to change from one full moon to another. But, an average month has a span of thirty days. This makes it very unlikely for a month to have two full moons.

          However, some months do have two full moons and it happens very rarely. If there are two full moons in a month, the second full moon is called ‘blue moon.’ This name is not linked to the colour. In a century, there will be forty-one blue moons.

Picture Credit : Google

 

 

How does a lunar eclipse occur?

          For a while, we have been talking about sunlight illuminating the Moon. What would happen if something blocks the sunlight that it receives? Will the Moon vanish from the night sky?

          In some instances, the Earth blocks the sunlight that is supposed to fall on the surface of the Moon. This happens when the Earth’s shadow falls on the Moon as it comes between the Sun and the Moon. This phenomenon is known as lunar eclipse.

          Lunar eclipse happens only during the full moon when the Earth either blocks sunlight completely or partially. Depending on this, lunar eclipse can be total or partial. However, the Moon will not disappear completely during the eclipse. This is because of a small amount of indirect sunlight that falls on it.

Picture Credit : Google

 

 

Why does the Moon take more time to change from a new moon to the next new moon than the time taken for one trip round the Earth?

          It takes almost 27 days for the Moon to complete one trip around the Earth. This is known as the sidereal month. But it takes almost 29 days to change from a new moon to the next new moon. This is known as the synodic month. There is a difference of roughly two days. Wonder why?

          We already know that the Moon’s phases change according to the sunlight that falls on it and new moon occurs when the Moon is placed between the Earth and the Sun.

          While the Moon moves around it, the Earth moves around the Sun. The Earth moves farther in space during the time the Moon completes one orbit. So, for the Moon to come between the Earth and the Sun again, it has to move a little farther. It takes two days for the Moon to travel this extra distance.

Picture Credit : Google

 

 

How is waxing different from waning?

          The shape of the Moon changes throughout the lunar month. The period in which the new moon grows to a full moon and back to another new moon is known as a lunar month.

          A lunar month is characterized by waxing and waning. Waxing occurs between the new moon and full moon, when the moon grows in size. The side of the Moon illuminated by the sunlight becomes bigger; it grows from a waxing crescent to waxing gibbous and then to full moon. During the gibbous phase, 51-99 per cent of the moon’s surface is illuminated.

          On the other hand, waning occurs between the full moon and new moon. When the Moon is waning, its surface illuminated by the sunlight decreases day-by-day. The Moon changes from full moon to the waning gibbous phase. It then changes to the waning crescent and finally the new moon.

Picture Credit : Google

 

 

How is a full moon different from a new moon?

          When the Moon and Sun are placed at opposite directions from the Earth, the sunlight falls on the side facing the Earth. Therefore, the Moon appears as a round shining disc and is known as full moon.

          On the other hand, when the Moon comes between the Earth and the Sun, sunlight falls on the side that faces away from the Earth. During this time, the side facing the Earth appears dark and is known as new moon. The sky looks bright during the full moon while the Moon will not be visible during the new moon, making it dull.

Picture Credit : Google