What will happen in next 5 billion years, when the Sun turns into a red giant and consumes Earth? Scientists have been grappling with this question for a long time. Will this event cause the extinction of the human race from the universe? Or is there a way to save the species from this apocalypse? Interstellar travel to a suitable planet that can be the next home for humans is a hypothetical way to save humankind. But, is it possible in reality? Even if we find such a planet, travelling via spaceships would take us hundreds and thousands of years to reach it.

This means that it would take humans several generations to find a new home. However, a recent research paper suggests that interstellar travel may be possible even without spaceships.

A new research paper published in the International Journal of Astrobiology says that extra-terrestrial civilisations may not need spaceships to travel to another star system.

Author Irina Romanovskaya, a Professor of Physics and Astronomy at Houston Community College, wrote in the paper that according to her theory, extra-terrestrial and alien civilisations could employ free-floating planets as interstellar transportation to visit, explore, and colonise planetary systems. These free-floating planets are also known as rogue planets.

Romanovskaya added that she proposes hypothetical extra-terrestrial civilizations’ technosignatures and artefacts for interstellar migration and colonisation using free-floating planets, as well as ways for tracking down their technosignatures and artefacts.

According to the author, rogue planets are capable of providing constant surface gravity, and large amounts of space and resources.

In 2021, researchers discovered 70 to 170 rogue planets in one region of the Milky Way. In 2020, a study suggested the presence of as many as 50 billion rogue planets in our galaxy.

The author explained four scenarios where rogue planets can be used for interstellar travel. However, she noted that “free-floating planets may not serve as a permanent means of escape from existential threats.”

The first scenario concerns a rogue planet passing close to an extra-terrestrial civilisation’s home world. The frequency with which this occurs is determined by the number of rogue planets in general.

In the second scenario, technology is used to guide a rogue planet closer to a civilisation’s home. They could choose an object from their own Oort Cloud – if they have one – and employ a propulsion system to send it towards a safe orbit around their planet if they had enough technology.

The third scenario is very similar to the second. It also involves a body from the civilisation’s solar system‘s farthest reaches. Romanovskaya cites our solar system’s minor planet Sedna as an example.

The fourth scenario also includes Sedna-like objects. When a star departs from the main sequence and expands, a critical distance is reached beyond which objects are ejected from the system rather than remaining gravitationally linked to the dying star.

The rogue planet isn’t a permanent residence in any of these circumstances, it’s merely a lifeboat.