Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale with each other, but their distances are not. From left to right the bodies are: the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
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Jupiter is responsible for both activating and organizing the architecture of our inner solar system and creating the necessary conditions for the formation of Earth itself, say the authors of a new paper published in the journal Advances in Science.
The 11.5-year solar orbit of our massive gas giant planet has long been known to be somewhat anomalous among the thousands of extrasolar planetary systems we’ve been able to observe so far.
But the team’s computer models in this new study provided an unexpected twist on the timing and influence Jupiter had in creating the architecture of our early inner solar system. Jupiter’s early development within 1.5 million years after the birth of our solar system, about 4.56 billion years ago, directly affected the accretion of the building blocks of Earth and other terrestrial planets.
By depleting gas from the inner Solar System, Jupiter helped preserve solids in the region we now call the habitable zone, Baibhav Srivastava, a graduate student in planetary science at Rice University in Houston and the paper’s lead author, tells me via email.
Our results suggest that the timing of Jupiter’s formation was crucial for keeping Earth’s components in the optimal position where they could combine and grow, Srivastava tells me. In that sense, Jupiter’s early formation may have been one of the key factors that made a life-bearing planet like Earth possible, he says.
Rocky Planet Formation
Jupiter’s early growth reshaped the evolution of the solar system and set the stage for the formation of rocky planets, Srivastava says. While the terrestrial planets themselves took tens to hundreds of millions of years to reach their final size, their building blocks (planetary embryos) formed within the first few million years, he says.
In a gas-rich planetary disk, the building blocks of terrestrial planets would otherwise have spiraled inward and been lost due to the effects of the gas on the objects, Srivastava says. But Jupiter’s presence and the resulting “bumps in the road” prevented that from happening, he says.
How did it work?
Jupiter’s massive gravity sent ripples through the disc of the newborn solar system, creating “cosmic traffic jams” that prevented small particles from entering the Sun, Rice University notes. Instead, these particles clustered in dense zones where they could aggregate into planetoids — the rocky seeds of planets, the university says.
As Jupiter grew—about 1.5 million years after the birth of the solar system—it opened a deep gap in the solar nebula, disrupting the internal flow of pebbles and dust, Srivastava says. This barrier delayed the supply of solid material to the inner solar system, he says.
What does all this tell us about our place in the galaxy?
By depleting gas from the inner Solar System, Jupiter created the conditions that allowed rocky planets to form and remain in orbits relatively far from the Sun, unlike the compact, nearby “super-Earths” we often see in other planetary systems, Srivastava says.
A unique solar system?
If Jupiter had formed much later, after about 2 million years, the growing planets would have spiraled inward toward the Sun, resulting in a system of nearby super-Earths rather than terrestrial planets relatively far away, Srivastava says.
As for planetary systems without such planets as Jupiter?
Planetary systems that do not have an early-forming Jupiter, or that have a giant planet that forms very late, may form rocky planets, Srivastava says. But these planets are likely to be larger, hotter and orbit much closer to their stars than those in our Solar System, he says.
The bottom line?
Jupiter didn’t just become the largest planet — it set the architecture for the entire inner solar system, Rice University planetary scientist Andre Izidoro, the paper’s second author, said in a statement. Without it, we might not have the Earth as we know it, he says.
