Aliens Already Visited Earth But Before Humans Evolved, Study Finds

Aliens are just waiting for the stars to let them visit Earth AGAIN. That is according to a study suggesting intelligent extraterrestrial life relies on the movement of star systems to travel across the Milky Way.

The study, published in The Astronomical Journal, provides a potential answer to the Fermi paradox that questions why humans never detected signs of extraterrestrial intelligence.Â

Researchers said that aliens might have been working on its next trip to Earth but they rely on movements of stars to get to specific destinations.

"If you don't account for motion of stars when you try to solve this problem, you're basically left with one of two solutions," Jonathan Carroll-Nellenback, study lead author and a computational scientist, told Business Insider. "Either nobody leaves their planet, or we are in fact the only technological civilization in the galaxy."

Star systems move on different paths at different speeds within the galaxy. But stars and its planets can pass orbit closer to another system.

Carroll-Nellenback said aliens might use such event to move from one place to another. Since star systems orbit closer, it could speed up their journey.

However, it might take years before stars get closer. This might explain the Fermi paradox and the reason why advanced civilizations take longer to spread across the Milky Way.

Another idea proposed by researchers is that aliens might have already visited Earth but before humans evolved. It might take multiple generations on the planet for extraterrestrial life to come back.

Researchers explained that our solar system orbits the Milky Way every 230 million years. If the aliens live on the other side of the galaxy, they might wait for millions of years for our planet to get closer to their star system.

"If long enough is a billion years, well then that's one solution to the Fermi paradox," Carroll-Nellenback said. "Habitable worlds are so rare that you have to wait longer than any civilization is expected to last before another one comes in range."

For the study, the researchers created computer models that simulated a civilization's spread across the galaxy. Each model showed different scenarios based on a civilization's proximity to star systems.

The team said the Milky Way might have habitable star systems that remain hidden from humans. Estimates show that the galaxy has up to 100 billion stars and 10 billion Earth-like planets.

Aliens Already Visited Earth But Before Humans Evolved, Study Finds

Fermi paradox raises the question of why humans never detected traces of extraterrestrial intelligence. Pixabay