Our planet Earth is named after the lumps of stuff that we live on, but with the oceans covering 70 percent of its surface and making up 99% of its living space, perhaps we should really call our home planet 'water.

Just ponder the fact that even though we still don't exactly know what's hiding in the murky depths, the seas are thought to host between 50 and 80 percent of all life on Earth, not only that but it's widely thought that life itself started in the oceans up to 4 (four) billion years ago.

So, who's with me shall we start our petition, if not planet water then how about planet Earth, 'but really mostly water' yeah', well of what we call it is this planet alone in its precious gift of oceans, are there other seas out there in the cosmos? Well, one of the reasons that Earth is able to have oceans at all is because it sits in something known as the habitable zone or Goldilocks zone. It's not too hot, and it's not too cold, it's sitting just the right distance from the Sun for any H2O to stay liquid, any closer and the sun's heat would cause water to evaporate into vapor to be lost to the vacuum of space, any further away and water would freeze into a shell of solid ice that'd be no good to man or beast. It just so happens at earth lies slap bang in the middle of our Suns Goldilocks zone, whilst closer venues is just a little bit too hot and further mars is a little bit too cold for watery oceans.



 There are some indications that both venues and mars may have had back when they were formed but sadly they are no more.

 Venus's evaporated to leave and an atmosphere rich in hydrogen, while on Mars an atmosphere like ours may have made it warm enough for a vast ocean to exist for a while but then over time solar winds stripped first the atmosphere and then the oceans away, but that's not the end of the story for oceans in our solar system. Even though no other celestial bodies lie within the habitable zone, some distant icy worlds are hiding a distinctly damp secret beneath their surfaces. Take Saturn’s tiny moon Enceladus for instance, being just five hundred kilometers in diameter and ten times further from the Sun that it is cold, and it doesn't send a chance of maintaining a liquid water ocean on its surface but scientists have found pretty good evidence that its icy crust is protecting a vast subsurface sea beneath its South Pole containing about the same amount of water as Lake Superior in North America.



 For a while now we've been aware of plumes of vapor being ejected from cracks in Enceladus's surface and in 2015 NASA's Cassini spacecraft took a dive through that plume to sample the chemicals it contains, remarkably it found that it not only contained water vapor but also carbon, nitrogen, hydrogen, and oxygen, some of the key ingredients for life. It's thought that the H2O is able to stay liquid beneath the ice, thanks to the heat from the moon's rocky core this heat, as well as minerals from the rocks could be enough to sustain simple bacteria and so tiny Enceladus may be a great candidate for extraterrestrial life.

Further subsurface oceans have been suggested for a whole host of other moons and planets in our solar system including Jupiter's icy moon Europa and even they relegated dwarf planet Pluto whose possible ocean could be kept liquid by its cause radioactive decay, I should say at this point if you're frankly not bothered about your oceans being made of water then you've got plenty of other options for liquid seas in the solar system. Inside Jupiter the intense pressures from the giant planet's gravity turned hydrogen which is normally a gas into a liquid, beneath the planets tumultuous clouds there's thought to be an immense ocean of liquid metallic hydrogen, 25,000 kilometers deep now to put that in perspective the deepest part of Earth's ocean is just 11 kilometers below the surface, and if that's not weird enough for you try Neptune or Uranus which might just contain oceans of liquid diamond, with solid diamond Bergs floating on top of them, weirdly diamonds behaves just like water when it freezes and melts, albeit at pressures 40 million times that we find here at the surface, but immense heat and pressure is just what you can find in the cause of Uranus and Neptune. So scientists think there is a real chance of finding real glittering oceans on these gassy giants, however as beautiful as a diamond sea might be it's fairly useless for us and for life in general.

 The fact of the matter is that in our solar system at least surface oceans of liquid water are incredibly rare, 'it's just ours in fact'. All is not lost though our solar system isn't the only one out there to date we found more than 3,500 (three-and-a-half) thousand planets orbiting other stars in the galaxy, using sensitive telescopes and some pretty clever physics. With these methods, we can tell the size, the mass, the density, and the orbital distance of balls of rock up to hundreds of light-years away, and with that information, we can make some educated guesses about any potential oceans on their surface.

One promising candidate is the memorably named Gliese1214b, orbiting a start 40 million light-years away, observations from the Hubble telescope have revealed that it's more than 2.5 (two-and-a-half) times the size of Earth, but nowhere near as heavy as we'd expect it to be if it was made of solid rock and a possible explanation for this low density is that it contains a lot of water making it as the scientists put it a Waterworld, just sadly without Kevin Costner.

Other alien planets have been found that are both a similar size to earth and that lie in the Goldilocks zone around their stars they're too far away for us to see if they have oceans on their surface but by simply being in the right place they properly represent our best hope of finding a watery Haven out in the depths of space. Although a few trillion kilometers, probably a bit too far to go for your next watersports holiday.

Luckily we have our own ocean brimming with wonders right here on our cosmic doorstep.

As always, let me know your comments, would you scuba dive beneath the surface of an icy moon or take a dip in the diamond seas of Uranus: