There are among the stars rare planets made up of carbon. Diamonds are an essential part of their interior.
Jupiter, Saturn, and many larger extrasolar planets have in their interiors diamond. They have hydrocarbons that fall to their interiors, where pressure and heat transforms them into diamond. When Arthur C Clarke wrote the first sequel to 2001, the Monolith turned Jupiter into a sun called Lucifer. It shot out diamonds. A mountain sized diamond crash-landed on Europa in the second sequel 2061.
More amazingly are worlds around carbon stars, those born in the deep wombs of nebulas where there are pockets of carbon monoxide. Carbon becomes the chief element there. On Earth, and the other terrestrial planets, silica binds with oxygen to form rock.
By volume, the Earth is 85 percent oxygen. About 45 percent of its mass is oxygen. In a sense, we live on an oxygen world. Perhaps if we were closer to the center of the galaxy, where heavier elements are more abundant, the composition of our planet would be different.
We have as trace elements too that make an important contribution to our world. Our bodies are similar to the ration of carbon, hydrogen, oxygen, and nitrogen found in Halley’s Comet, for example.
There are important radioactive elements that drive plate tectonics, the movement of the Earth’s crust, vital to controlling the amount of carbon dioxide in the atmosphere, deep within our interior. These are uranium, potassium, and thorium. Without them, we would be much more like Venus and have a contaminated surface like Mars with carbonates. That’s not good for life.
Were we closer to the center of the Milky Way, the elements would be different. Stars have more elements heavier than hydrogen and helium. These are called metals in astrophysics. The more metals a star has the more likely it is to have planets. Our world would be different with a different amount of these elements. We might have a larger planet because of a greater abundance of building material.
Size matters in the type of planet you have just as elements and location do. Titan is similar to make up to Triton, Neptune’s largest moon, and Pluto. Because it is closer to the sun and larger than Triton or Pluto, it has strange, but cold mirror of conditions of the early Earth. It has a crust that floats on an underground sea and lakes made of hydrocarbons. Pluto’s atmosphere freezes and thaws with how close it is to the Sun. Both Triton and Pluto have geysers.
One kind of world is carbon worlds with different elements. They have a thousand times more carbon than the Earth has. Earth and Venus have similar amounts of carbon. Earth manages to recycle the amount of carbon in the atmosphere. Venus does not.
They form deep inside the wombs of stellar nebulas where carbon is abundant. Like Triton, they have oceans and lakes of hydrocarbons. The surface is composed of a familiar substance, graphite and other carbon compounds. The atmosphere is like Venus and Mars with carbon dioxide. The planet might get as small as Ceres or as large as Neptune is. This is in the range of rocky planets.
There are mountains of diamond and carbon silicate. Carbon silicate is the same type of material you’ll find inside of gas tanksespecially in motorcycles. It prevents weathering of the surface and volcanoes. Watch your step, there are also patches of stick tar abundant here.
You can put them closer to a star than an oxygen planet. They have a lower melting point than silicates do. That’s the carbon silicate and carbon based titanium that make up part of their interiors. Of course, they have iron nickel cores just as the Earth does. Some may have water, which will make exotic minerals. The Earth has more minerals than the Moon because of water.
They might at the right distance from their suns for them to have life on their surface. It might use oxygen as food. Perhaps, a strange form of intelligence would develop here.
Beta Pictoris would make a candidate for this. Pulsar planets like 1257 + 12 may produce them. So will older stars. We find these more abundant in the center of the galaxy. Carbon meteors would form them.
Other exotic worlds might be primarily water. Iron may be the dominant element on others. There are also carbon monoxide planets. Again, size, location, and elements will play a role in what they become. Perhaps, some will have moons formed like ours when another planet hits them just right. The possibility for what a planet is has almost infinite variations, but there are diamond worlds out there.
