Diamonds in The Sky - Part 3: Diamond Oceans (Episode 1/2)

Imagine a huge ocean, with icebergs floating around... but it is not water… it is liquid diamond. The winds that push the icebergs around are not made of air, but are ultra-powerful currents of water! And on a bad weather day, it snows… diamond flakes!

And guess what... such a place exists.  

The conditions of pressure and temperature on our little blue planet are very common to us. Of course... we live in them! Yet, in absolute, conditions of pressure and temperature on Earth are just one combination among many that exist in our Universe. And some extreme ones can make matter behave completely bonkers!  

Weirdly, we do not need to fly to the outer universe, or even across our own galaxy to find these incredible diamond oceans. Just a tiny flea-hop of a bit less than 0.0005 light years, and we arrive on orbit of Neptune. Yes, these incredible diamond oceans could be present  in our own solar system!  

To be honest, everything I write here also applies to Uranus, but between the two outer gas giants, my favorite is by far Neptune, probably because of its deep blue color… So I chose Neptune for our little exploration.

This article will be divide into two posts: In the one you are reading now, I will guide you through a descriptive deep dive into Neptune's atmosphere until we reach the diamond ocean surrounding its core. All that you will experienced is based on the current status of our knowledge about this planet. 

In the the second part of this article, we will discover the conditions for diamond to be stable and learn how scientist have been able to measure its melting point despite the huge challenges such a measurement implies. We will conclude by showing how these results suggest the existence of diamond oceans surrounding the heart of carbonated gas giants like Neptune or Uranus.  I am currently finishing to write this part, and should be able to post it in a couple of days, so stay tuned!

1/ Let’s prepare the expedition: I upgraded our anti-grav suits for this visit!

I made serious upgrades to the anti-gravity suits that allowed us to go for a hike on the surface of a white dwarf in Episode 2. In addition to countering gravitational effects, a powerful pressurization and thermal isolation system allows to walk around (or swim around) environments subjected to ultra-high pressures and temperatures.

I also added some exterior sensors that measure parameters like wind, temperature, composition of the environment etc. An augmented reality system translates this data so that the user can experience touch, smell, feel cold or heat in a bearable way... For example, a 1300 km/h wind will feel for the user like a light 20 km/h breeze and diamond snow would feel like normal snow-flakes melting on his skin. 

2/ Let’s go for the big dive down Neptune's atmosphere!

We just arrived in orbit of Triton, Neptune’s largest moon. Triton has a weird behavior: its orbit is retrograde compared to the rotation of Neptune (If one considers Neptune like rotating on itself clockwise, Triton orbits anti-clockwise). Because of this, and also because of the strong similarities between its composition and that of Pluto’s, it is believed that Triton is actually a dwarf planet from the Kuiper Belt that was captured by Neptune. It is even larger than Pluto (around 2700km in diameter compared to 2400km for Pluto).   

Now we are in the airlock of our spaceship, ready to jump into space and direct our jet-packs towards Neptune. Are you ready for the big dive ? 

GO!     

The deep blue sphere of Neptune rushes towards us, and after a few minutes it covers all the angle of vision. An ocean of blueness! The first objects we encounter when entering the atmosphere are white cirrus-like clouds of condensed methane floating in the higher atmosphere.     

We pass them, and then some stink enters our suits via the augmented reality system. It smells like a busy day in Los Angeles: clouds of smog made up of various hydrocarbons, beurk… 

We move down… 

The atmosphere around us is mainly composed of hydrogen, helium and methane gas. Methane absorbs red light and diffuses blue light, ah…this is why Neptune looks Blue... The pressure increases gradually and at around 50 bars (about 50 times the pressure on Earth at ground level), a familiar sight arises: Clouds of … ice! Just before entering the foggy water ice clouds, the blueness above us makes us feel a little like home, as if we were on an airplane just above the clouds!  

Wow!!! we are being deflected from our linear trajectories by super strong lateral forces. I ask you to adjust the inertial dampener of your suit. Oh yeah, I forgot to tell you… Winds on Neptune are the most powerful in the solar system, reaching speeds above 2000km/h! It’s definitely a bumpy ride down! 

What now?
What is this aggressive stinky stench that seems to increase while we are going further down? The stink increases and soon becomes unbearable: it feels like we are in the middle of a stink bomb explosion! The clouds are not clouds of icy water anymore, but are composed mainly of hydrogen sulfide (H2S) and ammonia sulfide (NH4)2S, the latter being what stink bombs are made!

I start to regret the smog encountered earlier! Neither you or I are feeling too well because of the smell, so we both disconnect the smell sensors of our suits! Let's boost our rockets a little in order to dive out of here. 

Splash!!! Wow, what happened now?  

I look around, we are in some kind of liquid now… Liquid water! 

Actually, my sensors indicate that it is a liquid blend of water and ammonia. we are now in Neptune's equivalent of Earth’s mantle. Notice these little icy flakes of methane floating around us like little specks reflecting the flashlight of our suits. 

The deeper we go, the higher the pressure and the temperature… We must not be far from the core of the planet now… But wait... these flakes of methane are starting to have a different aspect… it’s not methane anymore… these flakes are tiny diamonds. Diamonds raining in a sea of water… 

As we dive deeper, the water becomes more and more slushy, and suddenly … 

... Splash again!!!! 

We are in another type of liquid now… wow... this is a very weird sensation… The very high temperatures make the liquid glow , and we need to adjust our suit's visual sensors to compensate… I ask you to stop your jets, and we both swim towards the surface of this weird dense liquid.  

We are now at the interface between two liquids. The above part is made of slushy water from which millions of tiny diamonds are raining into the lower part, this weird gluey ocean.

Mama-mia! I just realized! We are swimming in an ocean of liquid diamond. looking around, we can both see these huge chunks floating on an oily viscous surface: pure solid block of crystalline diamond… How shall we call these? “Dia-Bergs”?.   

With all the emotions rushing in our minds due to such an amazing sight, we decide to head back up to safety. If we had dived deeper into the diamond ocean, we would have eventually hit the ocean floor, and therefore landed on the surface of the planet’s core. The core is believed to be composed of a blend of high pressure ice, silicates (rocks), iron and other metals. 

This imaginary voyage is inspired from the state of our knowledge about Neptune’s composition. Of course, no probe has ever been so close to the core, and I doubt we will ever be able to observe directly such an environment due to the ultra high pressures and temperatures involved. So on what basis can we extrapolate that the core is surrounded by an ocean of liquid diamond on the surface of which are floating massive “dia-bergs” drenched by a drizzle of fine diamonds falling from the sky?  

Research involving extreme conditions of pressure and temperature has made some amazing progress this past decade. Truely dazzling results have been published. Such research suggests that under the conditions that exists near the core of outer giant gas planets, liquid diamond should logically exist as an ocean surrounding the core. 

In my next post, I will present the detail of these results in a way that even a high school student can fully grasp. I have nearly finished writing it and will post it in a couple of days, so stay tuned!

Previous episodes:

• Diamonds in The Sky - Part 1:
  The story of how our sun will become a massive diamond floating in the sky.
• Diamonds in The Sky - Part 2:
  Clathrate Stars

Image Credits:

• The post's thumbnail was created using a cut-out picture of Neptune by  NASA derivative work: Voxhominis  (link) with a background of  Paul Sapiano (link). Both pictures were found on wikimedia commons.
• The image of Neptune with the rings is by  By NASA (composite image by Jcpag2012)   via Wikimedia Commons (link)
• Elements of the planets-diamond frieze were found on Pixabay and on wikimedia commons (link1, link2)
• The image of Triton is by  ESO/L. Calçada via wikimedia commons (link)
• The picture of the methane clouds of Neptune was taken by the Voyager probe (JPL, link)
• The picture of the diamond ocean with the iceberg and the diamond rain was put together by @muphy using a picture found on wikimedia common and authored  "Visit Greenland from Nuuk" (link) 
• All pictures not mentioned in this list were found on Pixabay

Reference and text sources:

• Melting temperature of diamond at ultrahigh pressure. Eggert et al. (Nature Physics, Vol. 6, No. 1, 01.2010, p. 40-43.) (pdf download)
• https://en.wikipedia.org/wiki/Saturn 
• https://en.wikipedia.org/wiki/Uranus 
• https://en.wikipedia.org/wiki/Neptune  
• https://en.wikipedia.org/wiki/Jupiter
• "Outer planets may have oceans of diamond" by Eric Bland (link)
• "It rains solid diamonds on Uranus and Neptune" by Sarah Kaplan (link)

Hi,
I’m @muphy (see intro post),
My life revolves around music production, teaching sciences, and discovery through travel.
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