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Leaving Space For Water



Outer Space

On average, humans can only survive three days without water. Water is fundamental to life for humans, plants, and animals. When scientists explore outer space for signs of life, extraterrestrial water is one of the first things they look for. It was once believed that the solar system was dry with no signs of water. Today, scientists are finding water in unexpected places all over the galaxy. With the existence of water, comes the potential for life. These new findings provide motivation to keep searching the galaxies for new worlds and new life forms.

Extraterrestrial Liquid Water

Extraterrestrial liquid water is any water that’s in liquid form outside of Earth. Scientists are careful to make the distinction between water in its solid, liquid or gas forms. Water vapor on other planets is sometimes considered evidence that water exists on that surface. It is possible, however, that a planet has water vapor in its atmosphere but does not have any significant liquid water.

Evaluating the potential for water

Water is made up of hydrogen and oxygen. These two elements are the found abundantly throughout the universe. A technique called absorption spectroscopy is used to detect water on other planets. Scientists measure how objects in outer space absorb radiation across the electromagnetic spectrum. Geochemistry another way to detect water using the processes and concepts from chemistry to understand major geological systems, including the Solar System.

With these methods, scientists can evaluate a planet’s potential for water. Many experts believe that both Mars and Venus once had liquid water over large surface areas. While it’s no longer flowing on the surface, water may be underneath the crust, similar to Earth’s groundwater. There is no conclusive evidence for water in other planetary systems but there is a growing list of places with the potential for liquid water.


Europa is one of the moons orbiting Jupiter. For years people have speculated about the potential for water on Europa based on hints from its icy crust. The way this moon interacts with the pull of Jupiter’s gravity creates tidal effects. Beneath the moon’s icy surface, scientists think there’s an ocean full of liquid water heated by hydrothermal vents.


Enceladus is slightly smaller than Earth’s moon but it is one of the most intriguing objects in our solar system. One of Saturn’s inner moons, Enceladus has a high probability of life. Scientists think ice geysers shoot watery eruptions all across the moon’s surface. Evidence suggests the existence of a subsurface ocean that’s likely warmed by the tidal effects of Saturn.


Earth’s neighboring planet is believed to have once been covered in ocean water. The surface of Mars still has traces of water, including features that indicate seasonal changes in ices that cover the Red Planet. Scientists are interested in whether or not Mars still has water beneath its surface. If this water exists, scientists will then explore whether it’s ice or liquid and how much is available. NASA is planning future space missions to Mars with the intention of looking for signs of life.

Even if water on other planets doesn’t lead to new lifeforms, it will lead to new discoveries about the universe. The more scientists can track where water exists in outer space and what state it’s in, the more they can understand how the solar system was formed. This knowledge can then be applied to Earth as we remember how our planet is connected to the rest of the galaxy in a vast, complex system.