# Is it possible that tidal bulge (by Moon/Sun) is just a increase in the volume of ocean water?

#### rajen0201

I got an idea that Moon/Sun causes solid earth's volume change(by distorting Earth's spherical shape). Is it possible that ocean water volume increases due to gravitational pull by Moon/Sun? Also, due to this eccentric change, Earth's rotation gets unbalanced, So it tries to get balanced by bulging on the far side.

rod

#### rod

In your idea about *Earth's rotation gets unbalanced*, the unbalanced situation apparently attempts to balance again, is the Earth's rotation rate slowing down and the Moon receding from Earth? Example, https://www.space.com/41626-why-does-earth-rotate.html

"But things slow down, too. When the sun formed, it spun once around its axis every four days, Naoz said. But today, it takes about 25 days for the sun to spin once, she said. Its magnetic field interacts with the solar wind to slow its rotation, Naoz said. Even Earth's rotation decelerates. Gravity from the moon pulls on Earth in a way that ever so slightly slows it down. A 2016 analysis in the journal Proceedings of the Royal Society A of ancient eclipses showed that Earth's rotation slowed by about 6 hours over the last 2,740 years. That comes out to just 1.78 milliseconds over a century. So, while the sun will rise tomorrow, it just may be a tad late."

IG2007

#### zclayton

I got an idea that Moon/Sun causes solid earth's volume change(by distorting Earth's spherical shape). Is it possible that ocean water volume increases due to gravitational pull by Moon/Sun? Also, due to this eccentric change, Earth's rotation gets unbalanced, So it tries to get balanced by bulging on the far side.
Water is in-compressible. It will expand and contract with heat or cold. NO, tides are caused by the gravity of the sun or moon reducing the effect of earths gravity under themand on the opposite side. a study of orbital maechanics is needed to understand why this happens on the opposite side of the earth. The normal effect of earths gravity in other places changes the surface of equilibrium of the water causing it to appear to rise and fall. The time lag of this effect causes the high tide bulge to drag behind the rotation of the earth and this is what causes the earths rotation to slow over time. A reletively small mass of water constantly dragging behind slows the rotation down by a very small amount. And yes, the tidal effect also affects the solid part of the earth by an almost immeasurable amount.

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