Carbon planet

Some planets might be very special.

These worlds might look very different from Earth. They could have mountains made of diamond. They might even have rivers of oil.

These planets would likely have no water. This is because the carbon would react with any oxygen.

Scientists think a planet named Janssen might be one. It is much bigger than Earth.

These worlds are far away in space. It is fun to wonder about them.

Most planets in our solar system have lots of oxygen. Earth, Mars, and Venus are made of silicon and oxygen. But scientists think some planets might be different. They call these "carbon planets."

These worlds have more carbon than oxygen. A carbon planet would have an iron core. Above the core, there might be molten silicon carbide. This is a hard material. A layer of graphite could sit on top. Graphite is the same soft material in a pencil. If there is enough pressure, a thick layer of diamond might form. Volcanic eruptions could push these diamonds to the surface. This could make mountains of diamond!

The surface might have liquid or frozen hydrocarbons. Hydrocarbons are things like tar or methane. These planets would likely have no water. This is because carbon reacts with any oxygen that arrives.

One possible carbon planet is named Janssen. It is much bigger than Earth. It has eight times the mass of our world. Scientists think it is covered in graphite and diamond. Other small objects in space might also be made of diamond. We are still learning about these strange worlds.

Scientists think some planets might be very different from our own. Most planets we know, like Earth, are made of silicon and oxygen. We call these oxygen planets. But a "carbon planet" is a special kind of world. This type of planet has more carbon than oxygen. Carbon is a very common element in our universe. It is the fourth most common element by mass. It sits right behind hydrogen, helium, and oxygen.

A carbon planet would build itself in a unique way. It would likely have a core made of iron. Above the iron, there might be layers of molten silicon carbide and titanium carbide. A layer of graphite could sit on top of those. Graphite is the soft material used in pencils. If the pressure is high enough, a thick layer of diamond might form. Volcanic eruptions could even push these diamonds to the surface. This could create huge mountains made of diamond and silicon carbide.

The surface of these worlds would look very strange. Instead of water, they might have liquid or frozen hydrocarbons. Hydrocarbons include things like tar and methane. These planets would likely have no water at all. This happens because any oxygen that arrives from comets or asteroids reacts with the carbon. The atmosphere might be filled with carbon dioxide or carbon monoxide. It could even have a thick layer of carbon smog.

Researchers have studied how these planets might exist. Marc Kuchner and Sara Seager used the term "carbon planet" in 2005. They looked into these worlds after a suggestion about Jupiter. In 2020, a survey looked at 249 stars near our Sun. The study found that 12% of these stars might have carbon-rich systems. One possible example is a planet called 55 Cancri Ae. It orbits a star with a high carbon-to-oxygen ratio.

We have found some objects that might be carbon planets. One example is a planet named Janssen. Janssen has eight times the mass of Earth. It is also twice as wide as our planet. Scientists think it is covered in graphite and diamond instead of water and granite. It orbits its star, Copernicus, every 18 hours. Other objects, like the pulsar planet PSR J1719-1438 b, might also be made of solid diamond. These discoveries help us understand the many ways worlds can form.

A carbon planet is a hypothetical type of world that contains more carbon than oxygen. In our own Solar System, terrestrial planets like Earth, Mars, and Venus are primarily composed of silicon-oxygen compounds. These are often called "oxygen planets." Carbon is the fourth most abundant element in the universe by mass, following hydrogen, helium, and oxygen. If a protoplanetary disc is carbon-rich and oxygen-poor, it could form a planet with a very different chemistry.

The internal structure of a carbon planet would differ greatly from Earth. It would likely possess an iron-rich core similar to known terrestrial planets. Surrounding this core, there might be layers of molten silicon carbide and titanium carbide. Above these layers, a large amount of carbon could exist as graphite, which is the soft form of carbon. If the pressure is high enough, a thick substratum of diamond might form beneath the graphite. Volcanic activity could potentially push these diamonds toward the surface. This process might result in mountains made of diamond and silicon carbide.

The surface and atmosphere of these worlds would be quite extreme. Instead of water, the surface might contain liquid or frozen hydrocarbons, such as methane or tar. These planets would likely lack water because any oxygen delivered by comets or asteroids would react with the surface carbon. If the average surface temperature stays below 77 degrees Celsius, a weather cycle might be possible. The atmosphere of a cool carbon planet would consist mainly of carbon monoxide or carbon dioxide. It might also contain a significant amount of carbon smog.

The concept of the carbon planet was formally developed in 2005. Scientists Marc Kuchner and Sara Seager coined the term. They investigated these possibilities following a suggestion by Katharina Lodders regarding Jupiter's formation. While the idea is controversial, recent surveys provide interesting data. In 2020, a survey of 249 solar analog stars was conducted. Researchers found that 12% of these stars have carbon-to-oxygen ratios above 0.65. This makes them strong candidates for hosting carbon-rich planetary systems. One possible example is the exoplanet 55 Cancri Ae, which orbits a star with a ratio of 0.78.

Scientists have identified several objects that may serve as examples. The planet Janssen, announced in 2012, shows evidence of being a carbon planet. It has eight times the mass of Earth and twice the radius. Research suggests it is covered in diamond and graphite rather than granite and water. It orbits the star Copernicus once every 18 hours. Other objects, like the pulsar planets Draugr, Poltergeist, and Phobetor, might have formed from the disruption of carbon-producing stars.

Some researchers have also found evidence of carbon-rich objects near pulsars. In 2011, Matthew Bailes and his team reported on PSR J1719-1438 b. This is a small companion orbiting a pulsar. It has a diameter of 60,000 kilometers, which is five times larger than Earth. However, its mass is slightly more than that of Jupiter. This high density suggests a makeup of carbon and oxygen in a crystalline form. Some scientists hypothesize this object is the remaining inner core of an evaporated white dwarf star.

Understanding carbon planets helps scientists learn about the diversity of the universe. These worlds may be more common near the Galactic Center or in globular clusters. In these areas, stars have higher carbon-to-oxygen ratios than our Sun. As old stars die, they release large amounts of carbon into space. Over many generations of stars, the concentration of carbon in the universe increases. This suggests that the number of carbon planets could grow over time. Studying these hypothetical worlds allows us to map the chemical possibilities of space.