Water Worlds in Our Solar System
Water Worlds In Our Solar System
tl;dr: Water Worlds are vastly present even in our own Solar System and throughout the known Universe. Water throughout the Universe is extremely present and vastly greater than all of the water found on Earth, trillions of times over. There is even massive amounts of water in our own Solar System, which wasn’t confirmed until roughly 50 years ago. Lastly, Earth is the only known location where water exists in all three states: liquid, vapor and ice.
So There’s Water out in this Universe, You Say?
Although the existence of water in the universe as long been suspected, it was only confirmed in the 1960’s. The Universe is now known to be awash in water and although it is yet to be found in a liquid state elsewhere than on Earth, the amounts of water vapor in the Universe is staggering.
In just one instance, one water reservoir around a black hole some 12 billion light years away contains enough water to replace all the water on Earth a mind-numbing 140 trillion times, which is enough to supply several dozen galaxies with all the water they need to exist.
However, 12 billion light years is a very long way away, so it might be more profitable to look for water closer to home, such as within our Solar System; where the presence of water could indicate the presence of life.
But where does the water in the Universe and by extension, in the Solar System come from? How is it formed and how did Earth get its water? Let us look at where water comes from first.
How is Water Formed in Deep Space?
Water is a combination of hydrogen and oxygen, as we all know and current thinking is that the oxygen component of water comes from the remains of first-generation stars.
These stars were massive and although not as massive as was first believed, they were nevertheless massive enough to have had very short lives.
Their destruction in supernova explosions would have released massive amounts of oxygen, which would have been incorporated into second-generation stars; who in their turn, would have released some of the original oxygen, plus the oxygen created during their demise.
However, as the resulting dust clouds cooled, water would have formed as hydrogen (the most abundant element in the Universe) and the newly created oxygen combined under favorable conditions. Water in this form can exist either as ice crystals or as small accumulations of ice crystals on dust grains that are about the size of the particles in cigarette smoke.
Third-generation stars, such as our Solar System’s star, Sol, would have formed out of a relatively water-rich cloud of dust and gas. Some of this oxygen would no doubt been incorporated into the planets as they formed.
There are many ways in which this could have happened, among which is a very high surface temperature that would have boiled off any liquid water, the lack of atmospheric pressure that would also have caused water to boil off, or sublimate, and the lack of a stable magnetic field to protect a nascent atmosphere.
How in the Hell Did Water Get Here on Earth?
There are many ways in which water could have found its way in being created on Earth. This process could have happened at very high surface temperatures, which would have boiled off any liquid water.
The lack of atmospheric pressure would have caused water to boil off or sublimate and the lack of a stable magnetic field to protect an atmosphere would have been enough to cause the water to evaporate.
Given the nearly inconceivable fact that almost all Earth’s harbored and vast quantities of liquid oceans (in its early life), the water on Earth would have had to have been “imported” from another source.
Recent findings by several researchers have indicated that the water on Earth does not have the same chemical “signature” (deuterium-to-hydrogen enrichment ratio) as water elsewhere in the Solar System, which proves that the water on Earth is much younger than water found elsewhere.
Current evidence seems to point to comets as the most likely source of Earth’s water, but the question is a long way from being absolutely conclusive.
Water Worlds in our Solar System
At present, there are more than 20 known or suspected locations in our Solar System alone, in which water exists in various forms; liquid, vapor and ice. It is very likely that these 20 sources of water is the very water that existed in the nebula (cloud of dust and gas) out of which the Solar System was formed from.
Much remains to be discovered about the origin of all the water in our Solar System, but what is known is that vast quantities of water exists on some of the moons of Jupiter and Saturn, so let us look at what’s known about these locations where water is present.
Water Worlds on the Moons of Jupiter
The Water World of Europa
Europa is one of the largest moons of Jupiter and is known to have a crust consisting of ice which definitely contains water. This moon is also known to have water under its crust, where it exists either in a liquid state or a slush that contains a lot of water and some ice mixed.
How did Water Get on Europa?
Tidal effects caused by the gravitational influence of Jupiter causes the crust of Europa to shift, crack and reform, which is likely to be the mechanism which causes the ice “volcanoes” that have been observed on Europa.
Although the continuous movement of Europa’s ice-crust is keeping the water under the crust, in a liquid state, there also seems to be evidence that Europa has Hadley Cells.
If the water under the crust is in fact liquid; there’s an excellent chance that it might harbor life, since the liquid water is protected from the detrimental solar radiation by the crust which would likely kill off any life forms which are in the process of creation.
What forms this life is currently an open question, but the building blocks of life, amino acids and their constituents are plentiful in the Universe. As such, we might yet find life in our own back yard, so to speak. Hello manned trips to Jupiter!
The Water World of Callisto
It is known that the furthest of the four Galilean moons of Jupiter contains water, but at present, it is not known how much, if any, of it is in a liquid state.
Being the furthest from Jupiter, it is the least affected by the gas giant’s (Jupiter) gravity, which accounts for the lack of geologic activity in the crust. However, this lack of geologic activity could mean two things; either the entire moon is a ball of ice, or there is not enough water to allow for a sub-surface ocean to exist.
Neither question can currently be answered to a satisfactorily level at this time. Eventually we’ll have to dedicate a research mission to determine the conclusion of this issue.
The Water World of Ganymede
There is no clear, hard evidence that liquid water exists beneath the nearly 100 mile thick crust of ice. However, recent research into Jupiter’s Ganymede’s auroras (which is larger than Mercury) suggests that there might be warm, salty liquid water under the crust – hello aliens.
No geologic activity has been observed on Ganymede, likely because Ganymede is a lot further from Jupiter than Europa and its crust doesn’t have the pressure ridges that indicates movement of its crust.
Yet despite all the data which suggests water wouldn’t form on Ganymede, all speculation points to the fact that Ganymede’s crust is hiding liquid water.
Water Worlds on the Moons of Saturn
The Water World of Enceladus
Although this tiny moon of Saturn is only 310 miles in diameter; it is known to contain a liquid ocean under its ice-crust. The 1,000 tons of water this tiny world spews forth every hour and which constitutes the F-ring around Saturn, contains several organic molecules, various salts and other minerals.
The composition of this water seems to indicate that the probability of life on Enceladus is somewhat greater than on Europa (a moon of Jupiter), we need to get a hold of a sample of this liquid water, so we can definitely say one way or the other.
The causation which keeps the vast majority of the water on Enceladus are much the same as on Europa; tidal effects caused by Saturn’s gravity seem to drive a hydro-thermal cycle that in turn causes huge eruptions of water as the crust fractures, moves and eventually forms again.
The Water World of Dione
Apart from the other known water worlds in our Solar System; there are many Scientists and Astronomers who hypothesize that this moon of Saturn could support or contain water in various forms.
One of these locations is found on Dione, which has been called the “weaker copycat of Enceladus“. This moon may be less active in geological terms now than it has been in the past, but there are several reasons why it may have had a warmer and possibly even wet history.
Part of the reason these geological conditions are thought to help support the presence of water is its tall mountain peaks and, of course, the evidence of geologic activity year and years back.
Although there’s a remote possibility of water on this moon, it’s still conceivable that Dione retains a sufficient level of heat from its formation to harbor a small, liquid ocean under its icy crust.
The Water World of Mimas
Yet another possible candidate to hold a liquid ocean is Mimas, a small moon of Saturn. It is unlikely that it retains sufficient heat from its formation to keep water in a liquid state, but its wobbling motion around Saturn means that it might.
Of course, it’s wobbling motion could also indicate an irregularly shaped solid core, but its icy surface consists mostly of water ice which suggests at least the possibility that there could be liquid water present.
Other Possible Water Worlds
The Water World of Ceres
Until the arrival of the Dawn Space Probe in the asteroid belt between Mars and Jupiter, it was believed by most Scientists and Astronomers that Ceres was just another rocky astronomic object the largest in this region, nonetheless.
However, initial data sent back to Earth via the Deep Space Network from the Dawn Space Probe seems to suggest that Ceres isn’t as much of a rock as originally thought. Eventually it was determined that Ceres meets many of the traits needed to be considered a dwarf planet; with an icy crust that hides a slushy, salty ocean around a rocky core.
If this is the case, Ceres would be the largest and closest astronomic object to Earth in which liquid water (and possibly life) exists. Unfortunately, we will have to wait for the Dawn Space Probe to gather more data and send back to Earth’s Deep Space Network.
Water and Pluto?!?!
Another possibility of water in our Solar System is located right outside of the furthest region of the planets within our Solar System; Pluto. Pluto could very well hide a liquid or perhaps even a slushy ocean under it surface.
Tidal interactions between the dwarf planet Pluto and its large moon Charon could have helped keep oceans under their respective crusts liquid, much like the tidal interactions between Jupiter and Saturn, these two could be keeping the oceans on their bodies in a liquid state.
There’s no shortage of water in our Solar System; much less throughout the known Universe. It’s very exciting to think that there could be liquid water on other astronomical objects and even the slight possibility that it could help promote the existence of life – in one form or another.
Until we’re able to better understand and detect the existence of liquid water in object’s core, oceans and even surfaces; we’ll have to wait and see when technology catches up to our curiosity.