Jupiter May Have Destroyed a First Generation of Super-Earths in Our Solar System

Long before Mercury, Venus and Earth formed, our solar system may have harbored other planets. In fact, scientists believe that it may have possessed super-Earths, which are planets larger than Earth but smaller than Neptune. So what happened to these planets? It's likely that Jupiter, the largest planet, helped destroy them.

"Our work suggests that Jupiter's inward-outward migration could have destroyed a first generation of planets and set the stage for the formation of the mass-depleted terrestrial planets that our solar system has today," said Konstantin Batygin, one of the researchers, in a news release. "All of this fits beautifully with our other recent developments in understanding how the solar system evolved, while filling in some gaps."

Recent surveys of exoplanets have shown that about half of sun-like stars in our galactic neighborhood have orbiting planets. Yet none of these systems look like our own.Within Mercury's orbit, there is only a little debris, which are probably near-Earth asteroids that moved further inward, but no planets. This is in sharp contrast to other systems; these systems typically have one or more planets that are more massive than Earth that are closer to their suns than Mercury.

"Indeed, it appears that the solar system today is not the common representative of the galactic planetary census," said Batygin. "Instead, we are something of an outlier. But there is no reason to think that the dominant mode of planet formation throughout the galaxy should not have occurred here. It is more likely that subsequent changes have altered its original makeup."

In fact, the researchers believe that during the first few million years of the solar system's lifetime, Jupiter became so massive and gravitationally influential that it cleared a gap in the dusty disk around the sun. As the sun pulled the disk's gas toward itself, Jupiter also drifted inward. As it drifted inward, it encountered Saturn, and Jupiter and Saturn entered what is called an orbital resonance. This resonance eventually pushed Jupiter outward once more.

What's more interesting is that it's possible that the empty whole of the inner solar system may correspond to the orbit neighborhood where super-Earths are typically found around other stars. The scientists used simulations to show that as Jupiter moved inward, it pulled all the planetesimals it encountered along the way into orbital resonances and carried them toward the sun. As the planets ventured closer to the sun, their orbits became elliptical. These orbits eventually set off a cascade of collisions which violently broke them apart.

The findings reveal a bit more about the early history of our solar system. More specifically, it shows that it's possible that our Earth formed only after a first generation of planets was broken apart with the help of Jupiter.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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