Water is life. At least as we know it. Every living organism on Earth uses liquid water, and researchers studying the origin of life have found that the complex chemistry of life probably exists in water. A hot pool on the Earth’s surface or Near a deep sea vent.
That’s why planetary scientists are particularly interested in places outside Earth where liquid water exists.
meanwhile Earth Earth has liquid oceans on its surface, but water makes up only 0.2% of its mass. In contrast, some planets and moons are up to 50% water, which can mean oceans hundreds or even thousands of miles deep.
Let’s take a closer look at some of the most promising water worlds in our solar system and beyond.
Europe
Scientists have discovered that Jupiter’s moons Europe There was probably a liquid ocean beneath the ice. National Aeronautics and Space Administration (NASA)The Galileo project was launched in 1989. For nearly eight years, Galileo spacecraft Circulated JupiterThere, the interaction of Europa’s magnetic fields with Jupiter’s was observed, suggesting the presence of water inside the moon.
of Europa Clipper The mission is to Europa Determine if it is habitableThis will be the first time a spacecraft has journeyed to a watery world, and researchers are particularly interested in how water and rock mix deep inside Europa, as nutrients and chemicals could potentially support microbial life in the same way that marine vents on Earth can support life.
Callisto
CallistoIt is the second largest moon of Jupiter. There is a liquid ocean undergroundCallisto’s surface is the most cratered in the solar system, suggesting a lack of geological or weathering processes. But about 155 miles (250 kilometers) below the surface, a salty ocean may be interacting with rock layers, potentially creating a habitable environment deep inside the moon. Oxygen has also been detected in Callisto’s exosphere, the top of its thin atmosphere.
Ganymede
In 2015, scientists Hubble Space Telescope It is the largest moon of Jupiter. Ganymedeprobably Had an ocean of liquid water insideGanymede has its own magnetic field. Aurora Observations of Ganymede’s aurora reveal that an internal ocean of liquid water likely suppresses fluctuations in Ganymede’s magnetic field as it interacts with Jupiter’s.
Ganymede’s oceans are thought to be 60 miles (100 km) thick, nearly 10 times deeper than Earth’s oceans. Galileo satellites It probably formed from materials similar to those that surrounded Jupiter in its early stages. Solar SystemThis explains why each moon has a relatively high proportion of water.
Enceladus
Enceladus — Little Ice Moon Saturn — is one of the most intriguing places in the solar system where planetary scientists have found water, because icy geysers on Enceladus’ surface spew water and ice into space, providing a way for researchers to harvest material directly from inside the moon.
This water and ice erupts from an inland sea, and in 2005 Cassini spacecraft discovered These materials are thought to have erupted from the moon’s surface at speeds of around 800 miles per hour, and the warm vents are thought to provide the lunar ocean with minerals and nutrients essential for life.
Giant
Saturn’s largest moon, GiantTitan is completely different from other planets in the solar system. Its surface is covered with lakes, rivers, seas, clouds and rain made up of the hydrocarbons methane and ethane. It is believed to have an ocean of liquid water beneath its icy crust, which could potentially support life. It is also possible that life forms on its surface are completely different from those on Earth, as they may use different chemical pathways to generate energy.
Although Titan’s chemical composition is very different from Earth, the large moon has characteristics associated with habitability, including a thick atmosphere and dynamic geological and weathering processes.
TOI-1452b
In 2022, NASA Transiting exoplanet exploration satellitean international team of researchers Discovery of exoplanet TOI-1452 bThe planet is about 1.6 times the size of Earth Size of the Earth The planet is classified as a Super-Earth: it has five times the mass of Earth and its density suggests that the majority of the planet (perhaps 30%) is made up of water.
TOI-1452 b is located about 100 light years away from Earth. James Webb Space Telescope (J.W.S.T.).
LHS-1140b
In July 2024, researchers using JWST will The atmosphere of exoplanet LHS-1140 bThe planet, which may have a liquid ocean on its surface, orbits a red dwarf star that’s one-fifth the size of the Sun. Sun 48 inches Light years From Earth.
Additionally, JWST data suggests that the planet may be made up of 10 to 20 percent liquid water. LHS-1140 b orbits in such a way that the same side always faces the star. What’s more, current models suggest that the planet may be a giant snowball, meaning there may be a “bull’s-eye” ocean on the side that always faces the star.
Kepler 138 c and d
Two possible water planets, Kepler-138 c and Kepler-138 d, are Red dwarf A star 218 light years away from our solar system. In 2022, researchers determined that the apparent density of the planets suggests that these worlds May have high moisture content.
Researchers believe that up to half of the materials that make up these planets should be lighter than rock but heavier than hydrogen or helium — the most common element in the universe that fits this criteria is water.
HAT-P-11b Hat
In 2014, astronomers Water vapor discovered on Neptune-sized planet 124 light years away from Earth ExoplanetsThe planet, named HAT-P-11 b, is close to its parent star and orbits it once every five days. It’s a scorching hot planet with a surface temperature of over 1,000 degrees Fahrenheit (530 degrees Celsius), and is thought to have a rocky core and a gaseous atmosphere rich in hydrogen water vapor.
The researchers found water in HAT-P-11 b’s atmosphere using a method called transmission spectroscopy. When an exoplanet passes by its host star (from our perspective), the star’s light travels through the exoplanet’s atmosphere. Various particles in the atmosphere absorb some of the star’s light at specific wavelengths. By analyzing which wavelengths are absorbed, scientists can determine the chemical composition of the atmosphere.
K2-18b
In 2019, water vapor Found in the atmosphere The discovery of a super-Earth planet called K2-18 b, 110 light years away from our solar system, orbits a red dwarf star, at just the right distance for liquid water to exist on its surface.
But planetary scientists aren’t sure whether the planet is a rocky world or a giant ball of liquid and gas.
Additional Information
Based on current exoplanet data, Super-Earths and Sub-Neptunians are thought to be the most common planet classes in the galaxy, and some of these planets are likely water worlds. However, these planets are large, and the interaction of the water in their oceans with the rocky interior will determine how habitable these planets will be. More details on these dynamics are published in this study. Journal Nature.
Europa Clipper will provide scientists with unprecedented information about the habitability of small water planets, like those found around Jupiter and Saturn. Why the mission will visit Europa See the NASA mission page.
Water planets are thought to be widespread in the universe, and may be one of the best places to search for extraterrestrial life. For a discussion of how common water planets are, see Journal of Science.
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