Could aliens (or humans) travel to nearby stars without using spaceships?

Elon Musk warned a couple of years ago that travel to other planets was necessary as Earth would eventually be engulfed by the sun — but what if we didn’t need a spaceship?

That’s the rather out-there theory suggested in a scientific paper this week, which posits the idea that humans (and indeed extraterrestrials) could simply pilot ‘rogue planets’ through the universe.

Researchers believe there might be millions of rogue planets hurtling through our galaxy on their own.

Indeed, one study has suggested there could be more of them than there are stars.

The paper in the International Journal of Astrobiology is titled 'Migrating extraterrestrial civilizations and interstellar colonisation: implications for SETI and SETA'.

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Authored by Irina Romanovskaya, professor of physics and astronomy at Houston Community College, the study reads: “I propose that extraterrestrial civilisations may use free-floating planets as interstellar transportation to reach, explore, and colonize planetary systems.

"Free-floating planets can provide constant surface gravity, large amounts of space and resources,.

“Free-floating planets with surface and subsurface oceans can provide water as a consumable resource and for protection from space radiation."

Romanovskaya suggests that nuclear fusion could transform the surface of such free-floating planets into a place which could support life, ScienceAlert reports.

She suggests that if aliens are using such technology now, we might be able to detect them.

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"I propose possible techno signatures and artifacts that may be produced by extraterrestrial civilizations using free-floating planets for interstellar migration and interstellar colonisation, as well as strategies for the search for their techno signatures and artifacts," she writes.

In 2020, Polish researchers spotted a brief brightening of a star, caused, they believe, by an Earth-sized planet wandering in front of another star.

But the planet is thought to be a “rogue”, unbound by gravity, and about the size of our Earth.

Przemek Mroz, of the California Institute of Technology, told Live Science: "The odds of detecting such a low-mass object are extremely low.”

"Either we were very lucky, or such objects are very common in the Milky Way. They may be as common as stars."

Watch: Congress holds long-awaited hearing on UFOs