Exoplanets Have Earth-Like Interiors

The Earth's basic structure is made up of a thin outer crust, a thick mantle, and a core. In a recent study, researchers found that rocky exoplanets that orbit other stars may have a similar same three layers and interiors just like Earth.

"We wanted to see how Earth-like these rocky planets are. It turns out they are very Earth-like," Li Zeng, lead author from the Harvard-Smithsonian Center for Astrophysics, said in a news release.

In order to determine this theory, the researcher used a computer model known as the Preliminary Reference Earth Model (PREM), which is a standard model for the Earth's interior. This model was fixed to accommodate the various masses and compositions of six known, rocky exoplanets with well-measured masses and sizes.

The team found that even though these exoplanets differ from Earth, each should contain a nickel/iron core that makes up approximately 30 percent of the planet's mass. A third of the Earth's mass is in its core. The remaining of each planet would comprise of a mantle and a crust similar to Earth.

"We've only understood the Earth's structure for the past hundred years. Now we can calculate the structures of planets orbiting other stars, even though we can't visit them," Zeng said.

Based on the model indications, the researchers believe that some exoplanets may also have similar chemical compositions to Earth. This suggestions is also based on the abundance of some chemical elements such as oxygen, silicon, iron and magnesium, which are found in close by planetary systems.  

The findings of this study were published in The Astrophysical Journal.

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