Is the Earth Round? No (But It Isn’t Flat Either)!
From space it may look as if we live on a perfect sphere, but the earth is not round. Before the flat earthers get too excited, however, it is not flat either. Our planet is ... a bumpy spheroid.
It seems that nothing is perfect. Not even planet Earth. English physicist Isaac Newton was the first to propose that our earth was not perfectly round, but instead was a flattened sphere or "spheroid”.
Spheroid
Newton was right. The reason is that the earth’s rotation has an effect on its shape. Material located further from the axis of rotation swings outwards more, making our planet similar to a spheroid - flattened at the poles and swollen at the equator.
If you measure the distance from the centre of the earth to sea level at both the equator and the poles, the distance is at least 21 kilometres greater at the equator. Fun fact for a quiz: this means that the so-called highest mountain on Earth, Mount Everest, is not really the highest at all. Its summit at about 8,849 metres is the highest point above global mean sea level, but it is not the furthest point from the centre of the earth. That award goes to Ecuador's Mount Chimborazo. Thanks to its location near the equator (where the earth bulges outwards the most), its summit is 2,072 meters further from the centre of the earth than the peak of Mount Everest.
Uneven mass
We have said it already: nothing is perfect. So the earth is not a perfect spheroid. This is because its mass is unevenly distributed across the planet. The greater the concentration of mass, the stronger the gravity, creating lumps on the earth.
Furthermore, the shape of the earth is always changing over time. These changes are caused by shifts in mass inside the planet, the occasional meteorite strike, shifting tectonic plates creating mountains and valleys, the changing weight of the oceans deforming the earth's crust, rising ground levels caused by melting ice on land, and much more.
Taking measurements
To keep track of the "true" shape of the earth, measurements are constantly being made using GPS receivers, lasers, satellites and radio telescopes. All these high-tech tools help to show that our earth is definitely not flat, but it is not perfectly round either.