I did find some exoplanets listed on more than one list. But none of them showed up on all 4 lists! So much for ‘Weird is weird.’
The first one we’ll look at is 55 Cancri e, which somebody has nicknamed ‘The Diamond Planet. It is only 40 light-years from us, and one list says it is worth about $26.9 nonillion ($26.9 followed by 29 zeroes). None of the other planets on these lists come with a price tag, so why does this one? Because they figure about 1/3 of its surface is made of diamonds. It is only twice the size of Earth, but it is almost 8 times denser than Earth. There must be something there that is denser than Earth’s rocky core. There is speculation that it has a ‘weird’ chemistry from what we know on Earth, and that it might consist of graphite and other forms of carbon.
So why would so much of it be made of diamond? Diamonds are carbon that is exposed to high temperatures and intense pressure over time. And 55 Cancri e has plenty of both! Despite its size, it orbits its sun closely, about 1/25th the distance from our sun to Mercury. At that distance, its ‘year’ is 18 hours long, and it is tidally locked, meaning the same face of the planet is always pointed at its sun. On that sunny side of the planet, the temperature could be about 3900 degrees F. Plenty hot, I would think. And as dense as it is, anything that is not actually laying on the surface would soon find itself squeezed so hard, its molecules get really up close and personal. If that item was mostly carbon, that pressure and heat would produce a diamond.
So far, 3 of the lists agree about it, but the NASA list included some thoughts about it that the others didn’t. It has been proposed that 55 Cancri e has a rocky core surrounded by a layer of water in a ‘supercritical’ state where it is both liquid and gas. It is also thought this planet is topped by a blanket of steam.
Does that negate the idea of a big chunk of it being diamond? I don’t know. NASA didn’t mention graphite, carbon or diamonds. Yes, the name on each list is 55 Cancri e; I double and triple checked. I suppose all 3 lists could be right, but those who compiled the lists only mentioned the tidbits of information that they found fascinating. What do you think?