Europa is one of Jupiter's many moons. It is much smaller than most planets (with a radius of 1569 kilometers), but it may have the largest ocean in the solar system. In the 1990s, observations by the Galileo spacecraft found that Europa had an induced magnetic field that could only be generated by a fluid similar to conductive salt water, and the density of the fluid was close to that of seawater. According to current observations and calculations, the ocean depth on Europa can reach 75 to 120 kilometers! It is many times deeper than the oceans on earth!
Europa's internal structure contains a huge ocean, and covering this ocean and separating it from the icy outer interplanetary space is an ice of pure water about 12 kilometers long. In addition to the above theoretical evidence that an ocean may exist on Europa, direct observations also show that there are annular cracks on its surface formed by asteroid impacts, which are exactly the same as the cracks created by rocks on Earth's frozen lake surface. In addition, the widespread patchwork of broken ice on the surface of Europa also suggests the existence of a surging ocean underneath it.
So how could Europa have an ocean of liquid water in an extremely cold place so far away from the sun? It turns out that Jupiter's tidal heating and its own radioactive heat production are its main heat sources. Jupiter is 312 times the mass of Earth, and its huge gravity provides energy to Europa's liquid ocean. During Europa's orbit around Jupiter, Jupiter's gravity produced a huge tidal force on Europa. This tidal energy is converted into heat energy, thereby maintaining the liquid state of the sea, which is called tidal heating. It's like if you keep kneading a inflated balloon, and the temperature of the balloon will rise in a while.
This fact can't help but make us think: Is Europa's huge ocean home to life as colorful as the earth's ocean? This is one of the great interests of mankind in exploring the sky. Scientists currently envision launching a rocket onto Europa's ice shell, allowing it to use the heat it generates to drill through the ice and enter the ocean below for measurement and observation. Europa's oceans may contain simple life, such as bacteria-like microorganisms, which most likely rely on oxidizing chemicals in the water to gain energy.