Jupiter was previously double its current size and had a much stronger magnetic field, says the study

Understanding the early evolution of Jupiter helps to shed light on the broader history of how our solar system has developed its distinct structure. The gravity of Jupiter, often called “architect” of our solar system, played an essential role in the formation of orbital paths from other planets and the sculpture of the gas and dust disc from which they were formed.

In a new study published in the journal Natural astronomyKonstantin Batygin, professor of planetary science at Caltech; and Fred C. Adams, professor of physics and astronomy at the University of Michigan; Provide a detailed overview of the primordial state of Jupiter.

Their calculations reveal that around 3.8 million years after the formation of the first solids of the solar system – a key moment when the material disc around the sun, known as nebulous protoplanetary, was dissipated – Jupiter was significantly greater and had an even more powerful magnetic field.

“Our ultimate goal is to understand where we come from and to pin the first phases of the formation of the planet is essential to solve the puzzle,” explains Batygin. “It brings us closer to understanding how not only Jupiter, but the whole solar system took shape.”

Batygin and Adams addressed this question by studying the tiny moons of Jupiter Amalthea and Thebe, who were even closer to Jupiter than Io, the smallest and closest to the four great Galilean moons on the planet.

Because Malthea and Thebe have slightly tilted orbits, Batygin and Adams analyzed these small orbital differences to calculate Jupiter’s original size: about double its current radius, with a planned volume which is equivalent to more than 2,000 land. The researchers also determined that Jupiter’s magnetic field at the time was about 50 times stronger than today.

Adams underlines the remarkable imprint that the past has left on today’s solar system: “It is surprising that even after 4.5 billion years, enough clues remain to allow us to rebuild Jupiter’s physical state at the dawn of its existence.”

Above all, this information has been obtained thanks to independent constraints which bypass traditional uncertainties in planetary formation models – which are often based on hypotheses on the opacity of the gas, the accretion rate or the mass of the nucleus of heavy element. Instead, the team focused on the orbital dynamics of Jupiter moons and the conservation of the angular moment of the planet – directly measurable quantities.

Their analysis establishes an instantaneous clair of Jupiter at a time when the surrounding solar nebula evaporated, a pivot transition point when the building materials of the planet formation have disappeared and the primordial architecture of the solar system has been locked.

The results add crucial details to the theories of existing planet formation, which suggest that Jupiter and other giant planets around other stars formed via the basic accretion, a process by which a rocky and icy nucleus quickly brings together gas.

These fundamental models have been developed over the decades by many researchers, notably Dave Stevenson de Caltech, the planetary science teacher at Marvin L. Goldberger. This new study is based on this foundation by providing more exact measures of the size, rotation rate and magnetic conditions of Jupiter at an early time and pivot.

Batygin underlines that if Jupiter’s first moments remain obscured by uncertainty, current research considerably clarifies our image of the critical development stages of the planet. “What we have established here is a precious reference,” he says. “One point from which we can more confidence to rebuild the evolution of our solar system.”