A recent study suggests that if a super-Earth had formed between the orbits of Mars and Jupiter, it could have destabilised Earth’s climate and orbit, potentially making life on our planet impossible.
Simulations by Emily Simpson and Howard Chen, planetary scientists at the Florida Institute of Technology, reveal how such a scenario would have impacted the solar system's delicate balance.
Super-Earths, larger than Earth but smaller than Neptune, are common in exoplanetary systems across the Milky Way but are notably absent from our solar system. To understand the potential effects of a super-Earth within our planetary neighborhood, Simpson and Chen simulated various scenarios involving a hypothetical planet with 10 to 20 times Earth's mass placed between Mars and Jupiter.
The results showed that the gravitational influence of such a massive planet could have drastically disrupted the orbits of inner rocky planets, including Earth, Venus, and Mars. According to Howard Chen, the gravitational pull of a super-Earth could push these smaller planets into highly eccentric or tilted orbits. Such instability would trigger extreme climate shifts, ranging from severe ice ages to periods of intense global warming, undermining Earth's ability to support life.
Chen further noted that while our solar system's current configuration is unusual compared to many exoplanetary systems, this rarity may have been a stroke of luck. Without a super-Earth disrupting Earth's orbit, our planet has been able to maintain the climatic stability necessary for life to thrive.
The study raises questions about the habitability of planets in other star systems that include super-Earths. Even if a planet exists within the habitable zone, the presence of a super-Earth in close proximity could destabilise its orbit and climate, hindering the conditions necessary for the evolution of life.
While a slightly larger planet near Mars might have introduced harsher seasonal changes, Earth’s overall habitability might have remained intact. However, the researchers emphasised that the absence of such a massive neighbour near Mars and Jupiter has likely been a critical factor in preserving Earth's unique environment.