Has our solar system lost a planet?

Although Pluto lost its “planet nine” status when it was downgraded to a dwarf planet, there is ample evidence that our solar system had or currently has a major planet far beyond Pluto that may one day claim dominance. old mantle of Pluto and become the legitimate ninth. planet. Unusually regular orbital patterns observed in the Kuiper Belt suggest that a celestial body more massive than Pluto lurks beyond the distant band of icy debris at the edge of the solar system where Pluto, Eris and other dwarf planets live.

The hypothetical existence of a distant Planet Nine or “Planet X” remains controversial, but evidence continues to mount in its favor. It certainly wouldn’t be the first time a hypothetical planet has been discovered. Neptune was the first planet discovered by studying the orbits of other solar system bodies. Curiously, its location was discovered through predictions derived from pen-and-paper calculations of telescope observations.

Inadvertently, a recent astronomy paper in Nature revealed a high probability that a gas giant, similar to those in the outer solar system, could have been rapidly thrown from its orbit around the sun early in the evolution of a solar system. The existence of a “lost” planet nine early in the formation of the solar system’s history would go a long way to explaining how and why the solar system looks like it does today.

RELATED: What Scientists Know So Far About Planet Nine

Modeling the birth and evolution of feasible star systems, the team of collaborating scientists from China, France and the United States, ran around 14,000 simulations of the early solar system to understand how it came to look like this. it is today, with four terrestrial planets and an asteroid belt orbiting near the sun, four gaseous planets orbiting farther out, and a scattering of cold rocky bodies beyond the gas giants.

“What’s really cool is that exoplanet astronomers have already confirmed that a very high percentage of gas giant systems as well as super-terrestrial systems have gone through planetary system instabilities, and we think the system solar is similar,” continued Jacobson.

Curiously, the simulations strongly suggest that there was early instability in the orbits of the giant planets – Jupiter, Saturn, Uranus, Neptune and possibly Planet Nine. Such bodies would have been much closer to the proto-Sun at some point, before the gas merged with the sun and this really sets off strong fusion reactions that push gas and dust outward including said planets. According to the scientists, this triggered a rapid and chaotic movement towards their current orbits.

Simulations suggest that early gas giants had very circular and regular orbits at regular intervals from the sun; after the nascent star began to squeeze them outward, they experienced an unstable transition from compact, regular orbits aligned with the plane of the disc to current orbits.

Professor Seth Jacobson of Michigan State University, who participated in the study, called this “a universal source of planetary instability in the galaxy”.

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“We think all disks go through this, what astronomers call a transitional disk phase, where the disk is photo-evaporated from the inside out,” Jacobson told Salon, referring to the disk. proto-planetary of gas and dust that foreshadowed our (and all) solar systems. We can see nascent solar systems forming around the galaxy in the same way, suggesting that there is a similar pattern to the formation of all solar systems.

“What’s really cool is that exoplanet astronomers have already confirmed that a very high percentage of gas giant systems as well as super-terrestrial systems have gone through planetary system instabilities, and we think the system solar is similar,” continued Jacobson.

In a collapsed cloud of stellar debris – a gaseous solar nebula and possibly the remnants of a dead supernova – our proto-sun has begun to heat up. Heating and ionizing the gaseous elements in the disc, the energetic photon emissions from our young sun eventually expelled the gas from the protoplanetary disc through evaporation.

The inner rim of this gaseous disc would theoretically “drag” the planets with it as it expands outward. The gas giants’ initial position in the inner solar system would have been “a very robust trigger for instability,” Jacobson said. It could have knocked a Planet Nine-like world out of the solar system — forever.

Indeed, in 90% of the simulated scenarios, this instability was triggered. Planetary orbits have been stable for billions of years in our solar system. The mystery of our solar system’s early evolution, however, is still unclear. The location of Jupiter’s Trojan asteroids and the irregular satellites of the giant planets point to chaotic shuffling, as does the varied composition of Earth and its moon, which would require a great mix of different bodies. (It is widely believed that a Mars-sized body called Theia collided with early Earth and the detached material formed the Moon.)

Experts now realize that the timing of the migration of giant planets was a problem. Geological evidence has also drastically exceeded the timescale of this model, known as the “Nice” model (as in Nice, France): specifically, a series of three papers in a single issue of Nature presented a solution, originally suggesting the giant planetary instability event occurred about half a billion years after the formation of the solar system and would have relied on a gravitational encounter between two planets to trigger a chain of destabilizing reactions.

“The instability would still occur very early in the history of the solar system, a few million years after the start,” Jacobson added. “The sun would still be in its star cluster at that time. If there had been an ejected ice giant, then that ejected ice giant might not have really been ejected. It might have been captured in this elliptical orbit.”

If the ejection was too late, it would likely become a rogue planet. In this motion scenario, beginning within 10 million years of formation rather than 500 million years into the life of the solar system, the nursery star cluster in which the system originated may intercept the fleeing planet. The result is an extended elliptical orbit.

“During the lifetime of a nebular protoplanetary disk, the amount of gas in the disk decreases over time,” Jacobson pointed out. “Only when the disc has already obtained that the amount of gas in the disc is already low enough that the photoevaporation effect can take place. The photoevaporation effect then moves quite quickly. The transition phase of the disk is actually quite short and erases the disk from the inside out.” The effect is similar to that of a puddle around a fireplace, where the water closest to the fire evaporates quickly and that further away takes a bit longer.

Jacobson said the planets shifting was a surprise result of the simulation. “What I think even we didn’t fully understand until we started these simulations is that there’s still enough gas in the disk and that this process still takes enough time for it to happen. could significantly affect the planet’s orbits as the process unfolds,” he noted.

Why the solar system looks like this:

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