It is understood, we Earthlings are “visited”. We had the ultimate proof of this in 2017 with the interstellar object Oumuamua, then again in 2019 with 2I/Borisov, whose nature as a comet from elsewhere is beyond doubt. But then, why wouldn't we be frequented by much larger celestial objects, like wandering exoplanets or even dwarf stars (i.e. like the Sun or smaller)?
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The influence of a nanny or godmother in the Solar System
Not only is this astronomically possible, it is even the most probable according to a new study based on computer simulations. In fact, the Solar System would have benefited from a sort of giant godmother passing through our cosmic region…
Orbits have long been a great mystery to humans and a source of their misunderstanding of Nature. The ancients believed them to be circular, because of divine origin, and in their minds, one or more superior beings could not create anything other than perfection. Therefore, non-circular orbits would have been unbearable for their beliefs.
But as long as astronomers took this approach, planetary movements remained unpredictable. They even invented epicycles to make their supposedly perfect model stick to observations that contradicted them, notably the planet Mars moving forward and then backward in the sky (known as retrograde movement). It took the mathematical genius of Kepler (1571-1630) to understand that the orbits were indeed elliptical. And this German astronomer was very religious in a beautiful irony of scientific history.
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Today, we are almost certain that our gas planets (Jupiter, Saturn, Uranus and Neptune) migrated during the youth of the Solar System. Migrations which, for example, would have brought materials to the asteroid belt between Mars and Jupiter, around 4 billion years ago. But because of what, or who?
The simulations are clear: an interstellar super Jupiter has entered the Solar System
The Solar System formed about 4.56 billion years ago after the gravitational collapse of a cloud of gas and dust, first giving birth to the Sun, then with less than 1% of matter remaining to planets, moons, comets and other asteroids. This early childhood was nevertheless more or less chaotic, the orbits became less and less elliptical, for example. The Great Tack, this theory which today has a consensus in the scientific community, particularly on the migrations of the orbits of Jupiter and Saturn, did not yet have an absolutely established cause.
And in fact, new numerical simulations show that the very close passage, just 20 astronomical units from the Sun – therefore between Saturn and Uranus – of a very massive exoplanet is even more probable than all the other scenarios considered so far. This interstellar visitor, coming from the confines of space, would “weigh” between 2 and 50 times the mass of Jupiter! In the high range, it would no longer even be a planet, but a brown dwarf star, a kind of astrophysical object between the planet and the star. This being said, the researchers' simulations prove to be more effective with a mass of eight Jupiters, which is already enormous.
For now, this hypothesis only produces the evolution of the Solar System in 1% of the simulations performed, but it is actually a good result, at least the best we have. Indeed, the other scenarios only reproduce it in 1 per 1000 or 10,000 simulations. It is therefore the most credible to date.
Sources :
Universtoday
arXiv (scientific publication)
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