Original title: What the Solar System Can Teach Us About Rocky Exoplanets
Paul K. Byrne, Claire Marie Guimond, Peter A. Cawood, Michael J. Way +8 · September 2026
Astronomers keep discovering more rocky planets outside our solar system, and these worlds show huge variety. Researchers want to understand their interiors, surfaces, and climates. To do this, they looked at rocky bodies in our own Solar System. They examined modern Earth and tracked how it changed over its history. Then they analyzed Venus, Mars, Mercury, the Moon, and Io to see their similarities, differences, and how they evolved. They also looked at types of rocky exoplanets that have no direct match in our Solar System, finding they are still variations on a common theme. The main takeaway is that rocky worlds change over time, sometimes dramatically. Worlds with similar size and mass can end up with vastly different planetary outcomes.
Two identical houses are built side by side. One is carefully maintained and renovated, the other is neglected and eventually falls apart. They end up looking nothing alike. Here, the Solar System's rocky planets are like those houses: they started from similar materials but evolved into vastly different worlds over billions of years.
When we discover a rocky exoplanet similar in size to Earth, we might assume it is Earth-like. This review shows that assumption is dangerous: Venus, Mars, and even Earth's Moon are all rocky bodies of similar size but with radically different climates and histories. Understanding this diversity helps astronomers decide which exoplanets are worth targeting for signs of life.
The abstract doesn't explicitly state limitations, but as a review it synthesizes existing knowledge and does not present new data or models. It focuses on Solar System analogs and only briefly considers exoplanets without counterparts, so the discussion of truly exotic worlds is limited.
Ask anything about this paper. Answers come from its abstract, and say so when the abstract doesn't cover your question.
What the Solar System Can Teach Us About Rocky Exoplanets — Paul K. Byrne, Claire Marie Guimond, Peter A. Cawood et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.