* Gravity: The Earth's gravity pulls everything towards its center, including water. This is the primary force keeping the oceans from floating away.
* Earth's Shape: While Earth is not perfectly round, it's more like a slightly flattened sphere (an oblate spheroid). This shape is due to the centrifugal force created by the Earth's rotation, which pushes outwards at the equator. This force is relatively small compared to gravity, but it does contribute to the overall shape.
* Atmospheric Pressure: The Earth's atmosphere creates a pressure that also helps keep water from escaping. It's not a huge factor compared to gravity, but it contributes nonetheless.
So, the water on Earth doesn't "fall" into space because of a combination of Earth's gravity, its slightly flattened shape, and atmospheric pressure.
It's important to remember that even with these forces, a tiny amount of water does escape Earth's atmosphere. This happens due to the Earth's magnetosphere and solar wind, which can push some water molecules out into space. This process is called atmospheric escape.
