What is geoid?

The geoid is like Earth’s “bumpy blanket”, it shows how Earth is shaped by gravity.

Imagine you're playing with a big ball and some water. If the ball was perfectly round, the water would sit evenly around it. But Earth isn’t perfectly round, it’s a bit squashed at the poles and bulging at the equator. Also, mountains and valleys make it even bumpier. That’s where the geoid comes in: it’s like drawing the shape of the water surface if Earth had no hills or valleys, just gravity pulling everything down evenly.

Think of the geoid as the “ground level” of Earth, not the real ground you walk on, but an imaginary line that follows how gravity pulls things. If you put a ball on a hill, it rolls down to the bottom, just like water would flow from high places to low ones. The geoid is what the water would look like if there were no hills or valleys to make it go up and down.

Scientists use the geoid to measure how high mountains are or how deep ocean trenches are, by comparing them to this imaginary “gravity line.” It helps them understand Earth’s shape in a way that's smooth and even, just like a playground with no bumps! The geoid is like Earth’s “bumpy blanket”, it shows how Earth is shaped by gravity.

Imagine you're playing with a big ball and some water. If the ball was perfectly round, the water would sit evenly around it. But Earth isn’t perfectly round, it’s a bit squashed at the poles and bulging at the equator. Also, mountains and valleys make it even bumpier. That’s where the geoid comes in: it’s like drawing the shape of the water surface if Earth had no hills or valleys, just gravity pulling everything down evenly.