According to foreign media reports, a new study from the University of Arizona shows that Jupiter’s four largest moons are warm because of the tidal forces generated by their gravitational fields pulling each other. This tidal heating may help to explain the evolution of Jupiter’s satellite system. Since NASA’s Pioneer 10 flew over Jupiter in 1973, this giant planet has brought us more and more surprises. What’s puzzling is that the four largest of Jupiter’s 80 moons – Galilean moons IO, Europa, Ganymede and Callisto – are not ice capped rock balls at 484 million miles (778 million kilometers) from the sun. On the contrary, three of the satellites are so hot that they can form a global ocean below the surface, while the fourth has a very high internal temperature and is full of active volcanoes. < / P > < p > the most obvious explanation for this is the tidal force generated by Jupiter’s gravity. When the tidal force stretches and compresses the satellites, their temperature will rise enough to keep the satellite’s interior liquid and not cool down with the geological age. However, according to research by the Arizona team of Hamish hay, a postdoctoral fellow at the Jet Propulsion Laboratory in Pasadena, California, these Jupiter tides are not enough to explain the heat inside the planet. < / P > < p > this is because Jupiter’s four major moons are too small to produce such a large tidal response to produce such a significant warming, but the gravity of other moons in Jupiter’s system is another matter. There is a phenomenon called tidal resonance. < / P > < p > “resonance generates more heat,” hay points out. “Basically, if you push any object or system and let go, it will oscillate at its own natural frequency. If you keep pushing the system at the right frequency, these oscillations will get bigger and bigger, just like you push a swing. If you push the swing at the right time, it will swing higher, but if the timing is not right, the swing’s movement will be suppressed < / P > < p > “these tidal resonances have been discovered before this work, but only the tides caused by Jupiter have been discovered recently, which can only produce such resonance effects when the ocean is very thin (less than 300 meters or less than 1000 feet), which is unlikely to happen. When the tidal force acts on the ocean, it will produce tidal waves on the surface and eventually propagate around the equator with a certain frequency or period < p > < p > by running a computer model, the Arizona team found that Jupiter alone was not enough to produce the right resonant frequency in a satellite, but when other satellites were inserted into the equation, tidal forces began to match each satellite’s resonant frequency. More heat is generated, and if the thickness of the underground ocean is in the right range, the water or rock inside will melt, much closer to current estimates. According to hay, current models assume that tidal resonance is still relatively mild, so the next step will be to remove this limitation. In addition to providing a mechanism to explain the heating of Galileo satellites, the model can also help calculate the true depth of their oceans. Apple extends AppleCare + purchase period: users can decide within 60 days