Does the Solar System have 5 more planets similar to Earth?

Some Earth-like rocky planets that were "abducted" by the Sun billions of years ago may still be lurking around us .

A study recently published in the scientific journal Astrophysical Journal Letters suggests that the Solar System could have as many as nine rocky planets, not just the four we know about.

Earth is a typical rocky planet. The other three familiar rocky planets are Mercury, Venus, and Mars, which are composed mainly of rock rather than a thick layer of gas like the gas planets group including Jupiter, Saturn, etc.

An illustration depicting Earth-like worlds floating at the edge of the Solar System - (Photo: LIVE SCIENCE).

A research team led by astrophysicist Amir Siraj, Director of the Interstellar Object Research Program at Princeton University (USA), believes that five other rocky planets are lurking on the outskirts of the Solar System.

According to Live Science , unlike Earth and its known "friends" , these worlds were not born from the protoplanetary disk of the Solar System, but are free-floating planets (FFP).

There are numerous FFPs that have been shown to exist in interstellar space, with origins that remain a mystery. One theory suggests that they are directly formed from gas and dust like stars. Another argues that they are ejected from star systems after catastrophic collisions.

About 2-5 FFPs may have been "abducted" by the early Solar System, a Princeton University study found through 100 million different simulations.

They are similar to Earth but slightly smaller, ranging in size from Mercury to Mars.

And they're trapped in the Oort Cloud , a vast structure at the edge of the Solar System that's home to countless icy asteroids and comets.

Although the Oort cloud is still attached to the Solar System, it is actually located outside the heliosphere, meaning it is "out of control" of the plasma winds from the Sun, so these hypothetical planets can be considered as just "loosely attached" to the outer edge of the Solar System.

They can be as far away as 1,400 astronomical units (AU). One AU is about the distance from the Sun to Earth.

This is not the first time the "abducted planet" hypothesis has been proposed and proven, but it is the first time it has been assigned to the Solar System.

More specifically, these planets are believed to be independent of "Planet X" , a hypothetical world located in space outside the orbit of Neptune, which is believed to be much larger than Earth and could take 10,000-20,000 years to complete one rotation.

This mysterious world called X is indicated through indirect evidence of how it interacts with its surroundings, but there is still much controversy and no direct evidence.