In Liu Cixin’s short story “Wandering land (opens in new tab)” (first published in the Chinese magazine Science Fiction World in July 2000), Cixin portrays a scenario in which the planet’s leaders agree to promote earth out of solar system to escape from a loved one solar flare which is expected to destroy all terrestrial planets.
This story is, of course, based in the realm of fiction, but could Earth ever really leave the solar system?
“It’s very unlikely,” Matteo Ceriotti, an aerospace and space systems engineer engineering lecturer at the University of Glasgow in the UK, told Live Science in an email.
However, as Ceriotti explained, “unlikely” doesn’t mean it’s “impossible” and suggested a way it could theoretically be done.
“Earth can be thrown out of its orbit by the action of a massive interstellar object, flying through interstellar space and coming into the solar system and passing by Earth,” he said.
Connected: What if Earth was a super-earth?
“In this close encounter, known as a ‘flyby,’ Earth and the object would exchange energy and momentum, and Earth’s orbit would be disrupted. If the object was fast, massive, and close enough, it could project Earth in an escape orbit directed outside the solar system.”
Timothy Davis, a senior lecturer in physics and astronomy at Cardiff University in the UK, agreed that the Earth could theoretically be ejected from the solar system and has his own hypothesis on how this could happen.
“The planets, as they now exist, are in stable orbits around the sun. However, if the Sun were to have a close encounter with another star, then gravitational the interactions of these bodies could perturb these orbits and potentially cause Earth to be ejected from the solar system,” Davis told Live Science in an email.
However, Davis noted that while this scenario is feasible, it is highly doubtful that it will happen – at least, in the foreseeable future.
“Such stellar encounters are quite rare,” Davis said. “For example, we know that the star Gliese 710 is expected to approach the Sun, in astronomical terms, in about a million years – but even this flyby is unlikely to disturb the planets.”
While it’s unlikely that external forces will force the Earth out of the solar system anytime soon, could humanity build machines capable of moving the planet to such an extent that it ends up being thrown?
“The energy required to remove the Earth from its orbit and eject it from the solar system is so massive—equal to sextillion (a 1 with 21 zeros behind it) megaton nuclear bombs detonating at once—that it seems impossible ,” Davis said. .
Although such an event is highly unlikely, what would happen if the Earth were to break away from the solar system? What impacts would occur if our home planet ended up sinking forever into the depths of the universe?
“Earth would fly into interstellar space until it was captured or swallowed by another star or a black hole,” Ceriotti said, adding that if Earth were to leave the solar system, it would probably result in the destruction of many—if not all – of the planet. life.
“It is unlikely that the atmosphere will remain: Earth’s global climate is very delicate due to a fine balance of radiation from the sun and energy dissipated in deep space. If this were to change, temperatures would change immediately and dramatically,” Ceriotti said.
Connected: Why isn’t the Earth perfectly round?
Davis agreed that most life on Earth would not survive this cataclysmic departure from the solar system.
“If the Earth were to leave the solar system, it is very likely that the vast majority of life as we know it would disappear. Almost all of the energy used by Earth’s living organisms comes from the Sun, either directly (e.g. plants that photosynthesize), or indirectly (eg herbivores that eat plants, and carnivores that eat herbivores).
“In this scenario, the further the Earth moves away from the Sun, the lower it is the temperature would be done. Eventually it would freeze completely. The only natural source of residual heat would be the decay of radioactive elements in the Earth’s crust, left over from the formation of the solar system,” Davis said.
Davis explained that some life might last, but in the end it would be doomed. “Some ‘extremophiles’ (animals/plants that can live in extreme environments) could subsist on this energy, but complex life would likely disappear entirely. This radioactive heat would only allow Earth to maintain a temperature of about minus 230 degrees C [Celsius, or minus 382 degrees Fahrenheit]. At these temperatures most of the atmosphere would also freeze, leaving Earth as a dead, icy world drifting between the stars,” Davis said.
Looking far into the future, Ceriotti added that our solar system will eventually be perturbed so severely that the Earth will either be knocked out of it, or destroyed entirely.
“We predict that our galaxy is on a collision course with Andromeda [our nearest neighbouring galaxy] in about 4.5 billion years. Such a massive collision of millions of stars would likely cause a major disruption in the solar system!” Ceriotti said. “It is also predicted that the Sun, in the next 5 billion years or so, will expand and engulf the Earth. “, Ceriotti added
So while Earth will eventually leave the solar system one way or another, it’s not something we’ll have to worry about for a few billion years yet. Maybe.
Originally published in Live Science.