Planets similar to earth have identical interiors

Washington D.C.: A new research has suggested that like earth other rocky planets also have a thin outer crust, a thick mantle and a Mars-sized core.

Lead author Li Zeng of the Harvard-Smithsonian Center for Astrophysics said that they wanted to see how Earth-like these rocky planets are and it turns out that they are very Earth-like.

To reach this conclusion Zeng and his co-authors applied a computer model known as the Preliminary Reference Earth Model (PREM), which is the standard model for Earth's interior.

They adjusted it to accommodate different masses and compositions, and applied it to six known rocky exoplanets with well-measured masses and physical sizes.

After their study, they found that the other planets, despite their differences from Earth, all should have a nickel/iron core containing about 30 per cent of the planet's mass.

In comparison, about a third of the Earth's mass is in its core. The remainder of each planet would be mantle and crust, just as with Earth.

Zeng said that they have understood the Earth's structure for the past hundred years. Now they can calculate the structures of planets orbiting other stars, even though they can't visit them.

The new code also can be applied to smaller, icier worlds like the moons and dwarf planets in the outer solar system.

The model assumes that distant exoplanets have chemical compositions similar to Earth. This is reasonable based on the relevant abundances of key chemical elements like iron, magnesium, silicon, and oxygen in nearby systems.

The study is published in the Astrophysical Journal.