The untold truth in science fiction? The real Wandering Earth actually requires so many nuclear bombs!

Can the Earth leave the solar system?

How should it do this?

A collage of Earth and the Milky Way.

(Photo: Guillaume Preat/EyeEm via Getty Images)

In Liu Cixin's short story "The Wandering Earth" (first published in the July 2000 issue of Science Fiction World), an impending solar flare will destroy all Earth-like planets. In order to save humanity, Earth's leaders unanimously decide to push Earth out of the solar system.

Although fiction is real, is it possible that the Earth could actually leave the solar system?

Matteo Celiotti, an aerospace engineer and lecturer in space systems engineering at the University of Glasgow in the United Kingdom, called the possibility of Earth leaving the solar system "extremely unlikely" in an email response to Live Science.

However, as Celioti said, "extremely low probability" does not mean that there is no possibility. In theory, there is indeed a feasible solution.

Celioti believes: "If a giant object from outer space flew into the solar system and passed by the earth at a close distance, the earth might be thrown out of its orbit under the huge force."

"Such close encounters are called 'flybys' and the Earth and the object will exchange energy and momentum, disrupting Earth's orbit. If the object has sufficient speed, size and proximity, it could potentially project Earth onto an escape trajectory pointing out of the solar system."

Timothy Davis, a senior lecturer in physics and astronomy at Cardiff University in the UK, agrees that in theory the Earth could be expelled from the solar system and has his own hypothesis as to why this might have happened.

"The planets today are in stable orbits around the sun," Davis told Live Science in an email. "However, if the sun were to have a close encounter with another star, the gravitational interaction of these objects could disrupt these orbits and potentially cause Earth to be ejected from the solar system."

At the same time, Davis also pointed out that this situation currently only exists in theory and is unlikely to happen in the future.

"Such stellar encounters are extremely rare. For example, we know that Gliese 710 is expected to make a close pass by the Sun in about a million years, but even this flyby is unlikely to rock the planets," Davis said.

Although it is difficult for external forces to force the Earth to leave the solar system immediately, can humans build a machine that can move the Earth to such a large extent?

"The amount of energy required to nudge the Earth out of its orbit and propel it out of the solar system would be so great - the equivalent of detonating six megaton nuclear bombs simultaneously - that it would be virtually impossible," Davis said.

Although the probability of this happening is extremely low, what would happen if the Earth really left the solar system? What would happen if our Earth was finally gone forever?

"The Earth will keep flying through the universe until it is captured by another star or swallowed by a black hole," predicted Ceriotti, adding that almost all life on Earth would likely become extinct if it left the solar system.

"The atmosphere will no longer be sustainable at that time: while the sun continues to radiate the earth, energy is also constantly dissipating into the external universe. Under the delicate balance between the two, the global climate is very fragile. If this balance changes, the earth's temperature will change dramatically immediately." said Celiotti.

Davis agrees, and he also believes that most life on Earth would not be able to survive outside the solar system.

"If the Earth left the solar system, most life as we know it would probably die," Davis said. "Almost all the energy needed for life on Earth comes from the sun, for example, plants directly photosynthesize, and for example, carnivores eat herbivores, and herbivores eat plants, so the food chain is also indirectly affected by the sun.

"In this case, the farther the Earth is from the Sun, the lower its temperature will be. Eventually, the Earth will be completely frozen. Certain radioactive elements left in the Earth's crust when the solar system was formed will decay and become the only natural source of heat at that time."

As Davis explains, some life might survive, but it's only a matter of time before it dies out. "Some plants and animals that can live in extreme environments, called 'extremophiles,' might survive on this energy source, but most multicellular life would likely disappear completely. This radioactive heat would only keep the Earth at about -230 degrees Celsius (382 degrees Fahrenheit). At this temperature, much of the atmosphere would also freeze, turning the Earth into a dead world hurtling between the stars."

Looking further ahead, Ceriotti added that our solar system will eventually be severely disturbed, with Earth being ejected from it or possibly even destroyed entirely.

"We predict that our Milky Way galaxy will collide with our nearest neighbor, the Andromeda Galaxy, in about 4.5 billion years," said Ceriotti. "A super-massive collision involving millions of stars would likely cause major chaos in the solar system! And we also expect the sun to expand and engulf the Earth over the next 5 billion years or so."

So, while the Earth will eventually leave the Solar System one way or another, it's not something we need to worry about for the next several billion years - probably.

This article first appeared in Live Science magazine.

BY: Joe Phelan

FY: Continent

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