It rains liquid methane on Saturn’s moon Titan, but that is just the start of the weird things that might fall as rain. How do diamonds sound?
On Saturn’s moon Titan, it is a bleak affair: It’s cold (-290 degrees Fahrenheit), it’s dull and dark (not only because of the distance from the sun but also the hazy atmosphere that shrouds it), it has an unbreathable atmosphere, and it rains liquid methane.
Liquid methane?
Yep!
You see the whole of Titan is surrounded by a very thick atmosphere and because of this, a ‘methane system’ (akin to our hydrological cycle) has developed.
Just like when the Sun shines on our planet, a very similar thing happens on Titan. Liquid gets evaporated, it forms clouds, it rains on mountains and flows down rivers, until (provided it has not frozen) it ends up in one of Titan’s seas. But the liquid falling is methane, not water.
Also, just to add to the peculiarness of it would be like if you were to see this ‘rain’. The gravity is a lot weaker and therefore this rain would fall very slowly (about 6 times slower than the rain on our planet) with the raindrops being about 50% larger than what we are used to. You would therefore likely feel each raindrop falling on your suit.
And by suit, no, I do not mean your pressurised spacesuit, because on Titan, you do not need one. The atmosphere is dense enough to allow us to walk around solely with just an oxygen mask and a method of keeping us warm (presumably some other type of spacesuit, or maybe even just a very hot burrito…This is a joke please do not go to Titan armed with just a burrito).
So Titan’s rain sounds weird huh?
Well, that’s just the beginning, because it’s going to get a whole lot weirder.
This is because although methane rain may sound strange to us. It is not weird in the greater scheme of things.
Why? Well, methane rain is the only rain (other than our rain), we have ever witnessed falling on a planetary surface (note falling on a planetary surface).
Every other type of this kind of rain (namely, falling upon a planet and not evaporating before it reaches the surface) is a theory, because for all we know, the only actual rain that can fall on a surface of a planet is water or methane, because these are the only rains we have ever witnessed to do so.
But if that is true, do you really think that in the great expanse of space, we just so happened to see the only other type of rain possible on the moon of a planet just three planets along?
Or, is the real answer that anything is possible (within scientific reason) and we have just not witnessed them happen yet?
Well, fortunately for humanity’s inquisitive mind, the latter is likely the correct answer. It is highly possible many other types of rain exist that can do the same thing as on Titan (flow as liquid on the surface after falling from clouds), but be a liquid other than water.
And let me explain…
To start with, we have seen/strongly believe other types of rain to exist, it is just we have not seen another planet or moon, where the rain actually reaches the surface.
For instance, on Venus, it rains sulfuric acid high in the atmosphere which evaporates before it hits the ground.
We believe it may snow frozen carbon dioxide as dry ice on Mars.
There is a theory that it may rain liquid helium on Jupiter.
And it also appears there is a kind of rain-like coronal rain that falls on the Sun in the form of a plasma.
So including Earth, that’s four planets of the Solar System, a moon and the Sun, showing evidence that there might be some form of rain cycle and every one of them seems different and unique to the last.
So all good so far, if all these types of rain could exist then so too surely they could form a hydrological cycle akin to us on some far off planet, right?
And arguably, it seems foolish to dispute this. If all these kinds of rain can fall then surely they can hit the ground and form lakes somewhere. There must be a sulphuric acid lake or a helium lake out there?
But in saying this, that is not the point of this article, we wanted to see what weird rain the could the universe throw at us. So we can get an idea of what bodies of ‘water’ might exist. So…
Strap yourself in because it is going to get even weirder…
Because Saturn itself may rain diamonds and so too might Neptune and Uranus (but this time even stranger because it might be doing this thousands of kilometres within itself).
Weirder still, on some of the more extreme planets that we know very little about, it ‘might’ rain iron on OGLE-TR-56b, rain rubies and sapphires on HAT-P-7b and glass on HD 189733b (at seven times the speed of sound… sideways).
So all in all, as you can see, with all these different types of rain that may exist, the fact we rain water may make us seem the weird outlier because it seems positively tame compared to some of these other theories.
That is because the universe has many secrets, even something as simple as extraterrestrial rain is a complex web that opens up a whole pandora’s box of randomness.
There might be glass, diamonds or iron falling right now and that’s just what we can guess at the moment. Who knows what else is out there?
But added to this, let's just for a moment ponder on the rain we do know exists: Liquid methane. If a planet hosts life but the rainfall is methane, what lifeform would have the ability to exist there? Nothing like we currently know about that is for sure, and it is mindboggling and amazing to think what we may discover it one day…And maybe it is on Titan right now, waiting to be discovered.