In most people’s minds, liquid water is usually associated with the earth, but on other planets in the solar system, there are also amazing amounts of liquid water. The earth is located in the habitable zone of the solar system. In astronomy, habitable zone refers to the region in the planetary system suitable for the development of life. Liquid water can exist on the surface of celestial bodies in this region. Outside this region, whether it’s a planet, a dwarf planet or a satellite, the water on its surface either evaporates or freezes to a solid. However, this does not mean that there is no liquid water on these planets. Scientists have found that a considerable amount of liquid water is hidden under the surface of these planets. Of course, to find them is not easy, scientists have to use all kinds of advanced detection technology. < / P > < p > beneath the icy surface of Jupiter’s moon Europa, there is a warm water world. It is not the heat of the sun that keeps the water liquid, but the gravity exerted by Jupiter. < / P > < p > in 2011, the Hubble Space Telescope discovered geysers gushing from Europa’s surface, which became evidence that the satellite had an underground ocean. Of these fountains, the highest reaches a height of 200 kilometers. Interestingly, NASA’s Galileo probe passed through one of the jets as early as 1997, but researchers didn’t know that until recently. The most important feature of Europa is the dark streaks on the surface of the planet, which is called “chaotic terrain”. It is formed by the breaking of ice, the rotation and inclination of ice and the re solidification. Some researchers believe that Europa’s surface features are caused by the flow of groundwater near low latitudes. Occasionally, the satellite also undergoes tectonic changes, possibly bringing material into the ocean below. Due to the existence of the subglacial ocean, Europa is also considered to be one of the most suitable planets in the solar system to nurture primitive life. And Ganymede, Jupiter’s largest moon, seems to have an ocean world hidden beneath the surface. In 2015, NASA scientists recorded the strange vibration patterns of Ganymede as evidence of its underground oceans. The calculation shows that the largest satellite in the solar system has an ocean as deep as 100 kilometers, and liquid water is very rich. For reference, the depth of the earth’s oceans is no more than 10 kilometers. < / P > < p > another underground ocean is on Saturn’s moon Enceladus, also known as Enceladus. Like Europa, the snowball moon occasionally ejects jets of water into space. NASA’s Cassini orbiter detected traces of salt and silica dust from these geysers, indicating a complex chemical process under the ice crust. Cassini also observed four secondary parallel thoughts, known as “tiger skin stripes,” in the Antarctic region of Enceladus. The observation shows that these streaks are low ridges with central rupture and high temperature, indicating that there are ice volcanoes in the center of the stripes. < / P > < p > liquid water may have existed on Enceladus for billions of years and is concentrated in the southern hemisphere. The liquid layer of Enceladus is about 8 to 10 kilometers deep and contains about as much water as Lake Superior, the largest of the Great Lakes in North America. < / P > < p > the highly elliptical orbit of Enceladus around Saturn and the tidal forces that follow keep its rocky core active and have a high temperature. The core is composed of silicates, which are high temperature and porous, and facilitate complex chemical reactions. Some researchers believe that this reaction may support the existence of life. In fact, scientists have detected organic molecules on this fascinating satellite, but further research is needed to find evidence of microbial existence. < / P > < p > dwarf planets in the asteroid belt are not usually associated with liquid water, but Ceres is a little special. Recent discoveries suggest that it may be a world with water. However, unlike the icy moons surrounding Jupiter and Saturn, Ceres has no tidal action from a gas giant to keep its liquid core warm. It is speculated that Ceres’ underground ocean may have been formed by an asteroid impact about 20 million years ago. Several bright spots appeared in the interior of the ocator crater formed at that time. < / P > < p > the heat generated by this impact has long been lost, but the water on Ceres has been muddy due to its high salt content. Sometimes, the water is forced to surface, leaving a highly reflective sediment. The dwarf planet may have a layer of liquid water, about 40 kilometers below the surface, hundreds of kilometers wide – a considerable body of water, perhaps already an ocean, given that Ceres is only 950 kilometers wide. < p > < p > there used to be vast oceans and turbulent rivers on the surface of Mars, but now most of the water has disappeared and escaped into outer space. There is still some water on Mars today, but it is almost all ice. However, research in 2018 suggests that there may be some stable liquid water near the red planet’s Antarctic ice cap. < / P > < p > the Mars Express probe of the European Space Agency (ESA) used the subsurface detection radar / altimeter (MARSIS) to detect the subsurface composition of Mars, showing a strange underground structure with a diameter of 20 km. Based on the physical characteristics detected, Italian scientists pointed out that this may mean the existence of liquid water, which may appear as salt pools or soil filled sludge. This may be good news for future Mars explorers, because liquid water will be a scarce resource on the red planet. < / P > < p > according to a study published earlier this year, the dwarf planet Pluto may also have an underground ocean. Data from NASA’s new horizons probe show that Pluto has an extremely active surface. Scientists have been studying the surface of the dwarf planet since the historic flyby of New Horizons in 2015. < / P > < p > Pluto seems to have experienced high temperatures at the beginning of its formation, allowing it to maintain its early underground oceans. Over time, the liquid freezes and expands, and Pluto’s surface begins to expand and break. Until today, Pluto may still have some liquid water under its frozen surface, a process similar to Ceres. < / P > < p > incredibly, liquid oceans can also exist in the atmospheres of the two ice giants in the solar system, Neptune and Uranus. Of course, this claim has not been confirmed, but a 2007 study suggests it is possible. Liquid water may be deep in the two planets, where there may be the right temperature and atmospheric pressure. According to NASA, if there is an ocean on Neptune and Uranus, the ocean may account for two-thirds of their total mass. < / P > < p > it seems inappropriate to include Lake Vostok in Antarctica, but this subglacial lake is arguably the most mysterious water body on earth. Lake Vostok is the largest underground lake in Antarctica, about 3770 meters under the ice sheet in the east of Antarctica. It is 260 kilometers long and 50 kilometers wide, which is equivalent to Lake Ontario, one of the five Great Lakes. The maximum depth of the lake is about 500 meters. What’s even more incredible is that the lake is under four kilometers of ice. < / P > < p > it is estimated that the waters of Lake Vostok are very old and formed about a million years ago. Some researchers believe that the environment of Lake Vostok is very similar to Europa. Therefore, if life can be found in Lake Vostok, it may provide strong evidence for the debate on whether there is life in Europa’s subglacial ocean. Lake Vostok was formed 14 million years ago and its water has been isolated from the rest of the world for about 1 million years. Therefore, the lake provides a unique environment for scientists to study ancient ecosystems, because the waters may contain species that have never been seen before. More importantly, Lake Vostok serves as a good analogy between Europa and Enceladus, which also have water under their ice shells. (Rentian) < A= target=_ blank>Chinese version of K-car: reading a10e design drawing exposure