An interstellar visitor may have warped the solar system billions of years ago, a new study has claimed.
Scientists suggested the enormous object disrupted the orbits of Jupiter, Saturn, Uranus and Neptune, which would explain the peculiarities of these four planets’ paths.
Prevailing solar system formation theories indicate that these planets should have at least started out following perfectly circular and share the same orbit.
But today, their paths are slightly off, leading astronomers to wonder what threw them of course.
The team put forth a possible answer to that question: a mysterious object flew through our solar system about four billion years ago and swept the giant planets into new orbits.
The researchers performed extensive computer simulations, running through 50,000 different scenarios, each simulation covering 20 million years of time.
The simulation that produced the most realistic results involves an object eight times more massive than Jupiter that came almost as close to the sun as Mars is.
This object would have come within 1.69 astronomical units of the sun, which is only slightly farther than the distance between the sun and Mars.
A mysterious object eight times the size of Jupiter may have flown through our solar system about four billion years ago and swept the giant planets into new orbits, researchers say
The researchers said that since there are tens of billions of sun-like stars in the universe, and these stars typically form in open clusters, it’s possible that a star with the right parameters encountered our solar system and caused today’s orbits.
‘In other words, we don’t need to look for a needle in a haystack to find a suitable encounter,’ the researchers wrote.
According to the ruling theory of how our solar system formed, each planet’s orbit should be arranged in concentric circles around the sun that all lie on the same plane.
But in reality, none of the eight planets follow perfectly circular orbits, and they don’t all lie on the same plane either.
Earth’s orbit, for example, is oval-shaped, and there is a seven-degree difference between its orbital plane and Mercury’s.
These deviations from the ‘ideal’ orbit are particularly puzzling when it comes to the four giant planets.
‘[T]he puzzle for theoretical astrophysics has long been to figure out how the orbits later became out-of-round and tilted from their mean plane by not too much and not too little,’ study co-author and planetary scientist Renu Malhotra told Live Science.
This is the conclusion of a new pre-print study which has yet to be reviewed by other scientists. Their study is currently available on the pre-print server arXiv.
Previous research has focused on how interactions between the planets themselves reshaped their orbits, Malhotra said, but ‘these hypotheses are not consistent with certain important details of the observed orbits,’ she added.
To test the foreign-object hypothesis, Malhotra and her colleagues used computer models of the four giant planets to perform 50,000 simulations of such flybys, each over 20 million years.
The ruling theory of how our solar system formed says each planet’s orbit should be arranged in concentric circles around the sun that all lie on the same plane, but that is not the case
For each simulation, the researchers adjusted the parameters of the object, including its mass, speed and how close it got to the sun.
After running each scenario, the simulation would yield theoretical orbits for the four giant planets that should result from the encounter with that object.
Most of the simulations created orbital conditions that did not match the giant planets’ orbits today, but about one percent of them did.
The visiting objects that yielded these near-match scenarios ranged from two to 50 times the size of Jupiter and plunged deep into the inner solar system, traveling far beyond Uranus’ orbit and sometimes even grazing Mercury’s path.
Many of these near-match scenarios had the object zooming through the inner solar system, which prompted the researchers to add the terrestrial planets — Mercury, Venus, Earth and Mars — into the simulations to see how they might affect the results.
But even with these four planets added in, the near-match scenarios still recreated the planets’ current orbits.
The study’s findings suggest that a single event could have been responsible for the slightly imperfect orbits that Jupiter, Saturn, Uranus and Neptune follow today.
While the odds that this exact scenario actually took place are slim — about one in 1,000 to one in 10,000 — it is not impossible.
