'Earth's gravity shaped the Moon'

According to the study published in the journal Science, our planet's gravity caused the "bulging" at the Moon's equator and could be the reason why the far side of it is higher than its near side.

"Since the Apollo missions... people have known that the topography on the far side of the Moon is much more elevated than anywhere else on the moon," said leader of the study Professor Ian Garrick-Bethell of the University of California.

"Our study is the first to quantify the structure and shape on the far side and in doing that, we were able to demonstrate that this topography bears the signature of a tidal process."

When the Moon was created four billion years ago, its crust floated on a sea of magma before it was solidified to its core.

Scientists say it was during this time that the Earth's gravity tug on the floating crust distorted its surface. The process, known as 'tidal heating' is very much like the Moon tugging on the Earth's oceans today which creates tides.

The 'tidal bulge' melted the Moon crust thinning it at the poles where the strain was greatest, while the crust around the equator remained thicker and fatter.

"You can imagine that the part of the Moon that's pointing towards the Earth will start to flex and begin to be drawn towards the Earth and away from the Earth on the far side, and during this, the poles will be stretched and heated," Bethell explained.

"The amount of strain in the rock is going to be greater at the poles so there will be more heating at the poles and there'll be thinner crust at the poles."

Bethel believes tidal processes can explain between 25 percent and 40 percent of the Moon's topography, the state-funded BBC reported.

Scientists say tidal bulging might occur across the whole solar system including the Earth, Jupiter's moon Europa and Saturn's largest moon Titan.