When the moon is new or full, the gravitational forces of the sun and moon are pulling at the same side of the earth. (See the diagram below.) This occurrence creates the extra large "spring" tides.
When the moon is at first and third quarter, the gravitational forces of the sun and moon are pulling at 90 degrees from each other. (see the diagram below.) This occurrence yeilds little net tides called neap tides.
Slide 22
Every few years people that measure such things (chronologists?) need to add a leap second to the year. The Earth's rotation is decelerating at a rate of about 0.002 seconds per day per century.
The Earth will eventually stop slowing down – when it’s rotation is equal to the moon’s orbital period !!!
The Proxigean Tide occurs when the Moon is at its closest point in its orbit to the Earth and in its New or Full Moon phase. At this time, its tidal effect on the Earth is maximum. The times when this will happen often coincide with major coastal flooding events. Between 1997 and 2020 there will be 102 times when this will happen.
The moon shows the same face to the Earth because it was deformed by Earth’s gravity when it was still molten. Earth uses this “memory” to grab the moon and slow its spin rate down.
WHY ?