Habitable Planets 06: Water Worlds & Ocean Planets
So today we are looking at Water Worlds, placesthat consist entirely of water on their surface with no land at all. Weâ€™ll be discussing how they might stillhave land life in spite of that, how life might evolve there, and how we might terraformsuch a planet ourselves. Now it has been a while since we were in theHabitable Planets series, weâ€™ve.
Been off covering a lot of other topics, many inter-connected,so it will be nice break to talk about a subject that is a lot more down to Earth, at leastas much as discussing an alien world could be considered down to Earth. Though by the standards of this channel thissubject is about as close as we come to. If youâ€™re new to the channel I will occasionallyreference associated topics weâ€™ve covered in more detail elsewhere, and youâ€™ll oftensee a video link pop-up you can click on to pause this video and watch that one in a newwindow.
You havenâ€™t gotten used to my voiceyet itâ€™s a good idea to turn on the closed caption subtitles on the video. We tend to move through a lot of info quicklyso anything that makes it easier for you to understand me is a good. On that note, if you are a veteran to thischannel I should add that we will be going at a slower pace for this video, I think Iâ€™vebeen slamming through material a little too quickly in recent ones and I felt like weshould take our time for this trip. Whenever we look at these planets in thisseries we have certain goals we aim to achieve and questions.
That need answering, and I thoughtIâ€™d list them out formally this time.
These are: 1) What are the specific traits of these planets? 2) Are there any important sub-categories? 3) How likely or uncommon are such planets? 4).
Them? 5) How likely is complex or intelligent life? 6) How would we terraform such a planet? Now most of the time in this series Iâ€™dask if we could terraform a given type of planet but if youâ€™re a regular to this channelyou know the answer is always yes, heck last week we.
Were talking about basically terraformingblack holes, so Iâ€™m not even going to bother answering if we can terraform a planet coveredin water, just talk about some of the options unique to Oceanic Planets.
Ditto, on a planet covered in liquid water,which is our main trait.
Used to define the Habitable Zone of a solar system, if liquidwater can exist there, it would seem a bit pointless to ask if life can emerge on suchplanets.
Weâ€™ll instead look at how in some casesit might.
Not, and some challenges some types of Oceanic planets might face for complexlife to emerge. So letâ€™s start with #1, what are the specifictraits of these planets? What makes a planet an Ocean World and whatother features might we expect. Well the simple answer is it is a planet almostcompletely covered in water.
Though it might have some small landmasses and ice at thepoles, and today we arenâ€™t interested in a world thatâ€™s totally covered in ice thoughwe will be talking about ice quite a lot, even on ones with none on the surface becausethereâ€™s a lot of different types of ice and some can exist at room temperature oreven temperatures that would boil water normally.
Defining this broad category ofplanets into those which contain little or no land, at least in the sense of land beingrocks and dirt left over from volcanic eruptions and tectonic upheaval above the sea level.
Us to predict how commonthat actually is on planets because we still donâ€™t know what drives our tectonic plates,or what the prime force driving them is. Thereâ€™s many theories, that itâ€™s convectionin the mantle over them or that old plates get denser and sink being the two most popularcurrently. And we donâ€™t know how much tidal forcesof moon or sun play a role in this. Stacked again that, we know the sun and moonboth play a huge. Waves crashing onto rock, tides lowering andraising the sea level, storms, rain, wind etc all act to erode rocky landmasses andin a world with no tectonic activity theyâ€™d.
Eventually wear down the landscape, and ifthey were stronger theyâ€™d do it faster.
World with very little tectonics and a greatdeal of erosive forces could easily become one in which there was no land even if theseas werenâ€™t very deep.
If your oceans are a lot deeper,itâ€™s much harder for land to emerge up through all that extra water. And water is very common in the universe becausehydrogen and oxygen are the first and third most abundant elements. Earth is just under a third each iron andoxygen, with the remaining third being.
Mostly silicon and magnesium, but oxygen is muchmore common in the crust and iron in the core. The rock and dirt you walk on, the water yourdrink and swim in.
Mostly oxygen, because oxygen is so common in the Universe. Yet hydrogen and helium are much more commonin.
The Universe and nearly absent from Earth, and oxygen is a lot less common on.
The PlanetMercury for instance. Weâ€™ve talked about this before and it comesdown to three big factors. The sun tends to hammer planets with ionizingradiation that strips off lighter elements, especially helium which canâ€™t chemicallybond to anything to form heavier molecules and solids. Retaining lighter elements then comes downto three things: 1) How massive or dense a planet is. Increasing these increases the escape velocityof the planet and those particles trying to flee it. Since that will help keep back some of theradiation stripping the particles and can bounce many fleeing ones back down, and.
Since that indicates both how much radiationit is being exposed to and what the overall temperature is. Temperature provides a large initial boostto each particles speed, especially lighter elements, that make them easier to whack withradiation and add enough speed to lift them off the. Weâ€™ve talked about that in more detail inthe Terraforming video. What it means in a nutshell is that planetsmuch lighter than earth generally wonâ€™t have true atmospheres and so canâ€™t haveliquid water either, water just.