OK, Planet Nine, pretty damn cool, OK actually pretty damn cold.
I redid my calculations and at 300 AU you will receive a paltry 33 millewatts/M2 of energy from the sun. It its orbit extends out to 60 AU that number drops to 8 mw/M2.
I emit more energy than that through my skin, I mean this is almost nothing.
This does make for some very strange possibilities, but I am having trouble finding data on what the energy flux coming from outer space actually adds up to. It is enough to overcome the solar wind emanating from the sun at that range so it is possible that there is more energy coming from elsewhere in the universe than there is coming from the sun at 300AU.
Even the closest star to Nine would still be 50,000 times as far away as the sun, but there are billions of them! And some of them are sending out a lot of energy.
But about atmosphere, yesterday I made a quick conjecture on what the atmosphere may contain, I did some more thought on this today while I was at work (don’t tell the boss).
H2 Likely most of the atmosphere, stays a gas until it gets really cold.
He Likely most of the rest of the atmosphere, stays gaseous until almost absolute zero.
O2 Not likely, if any happened to fall into the atmosphere it would react with other chemicals there.
C2N2 Nasty, stinky, stuff, possible, but most likely in the ice around the core.
H2O Good old water. There is likely a decent amount of this, as Ice XI, a fun form not found on Earth.
CH4 Methane, the greenhouse gas. If it is warm enough it would be in the atmosphere giving the planet a blueish tint, if not lakes or ice.
N2 Nitrogen is right on the edge here, may be a gas, may be a liquid, may e falling as snow. I am guessing that nitrogen snow would end up being little orthorhombic 3d flakes…
NH3 Ammonia, likely as a solid.
CO2 Only as a solid
CO =, good old Carbon Monoxide, actually possible as a liquid if it is warm enough…. Otherwise as a solid.
Amino Acids from space? There have been some suggestions that space is chocked full of the basic building blocks of nature. If they find this thing and it has a distinct reddish tint I am going to use that as an excuse, but I am guessing that there is going to be an atmosphere, there are going to be moons, and enough tidal heating to keep some of the methane in the form of a gas.
This brings up the other issue. Without a moon, and without tidal heating if this thing is just a rock with 10 times the mass of earth and no atmosphere it could be small…. Really small, like twice the radius of the Earth small, no atmosphere to hold in heat would make it the same temperature as the interstellar medium. And it could just be a black rock at the edge of space. In which case I suggest we call it Miranda.