Preliminary findings from a recent study presented at the European Geosciences Union General Assembly hint that planets like Venus—those swathed in thick carbon dioxide atmospheres—might be more common than Earth-like planets. Researchers suggest these hellish worlds could be twice as frequent in the galaxy.
While this research is still in its early stages and awaits peer review, it prompts us to rethink how often dense CO₂ atmospheres occur around rocky exoplanets. The lead author, Sean Jordan, a postdoctoral fellow at ETH Zurich, emphasizes that as rocky planets cool from their molten beginnings, they often develop thick CO₂ atmospheres, rather than the oxygen-rich environments that support life. In simpler terms, creating a planet like Earth is a more complex, rare event.
Jordan explains that forming a heavy CO₂ atmosphere from an early magma state is plausible. He argues that building a planet that avoids a runaway greenhouse effect—as Earth has—requires more specific conditions than it might seem.
The challenge lies in our current inability to confirm whether rocky exoplanets actually have atmospheres, especially since many orbit red dwarf stars that emit high-energy radiation. Scientists can’t yet determine if a planet can retain its atmosphere over time.
Interestingly, Venus is our closest example of such an atmosphere. Despite its proximity at just 41 million kilometers away, Venus remains underexplored. Historical missions, like the Soviet Venera landers in the 1970s and ESA’s Venus Express from 2006 to 2014, provided valuable insights but modern exploration has stagnated. Jordan mentioned that we have not sent a dedicated probe with current technology to study Venus since those early missions.
The lack of recent explorations means we miss crucial data on its atmosphere. As Jordan puts it, this gap is surprising given Venus’s importance in understanding the atmospheric conditions of potentially similar worlds.
Looking ahead, Jordan estimates it will take decades to confirm the existence of Venus-like atmospheres on exoplanets, especially as NASA’s proposed missions, DAVINCI and VERITAS, face budget cuts. The situation creates a tension between the growing scientific interest in Venus and the political decisions that may hinder exploration.
In a thought-provoking statement, Jordan suggests that Venus may not have “gone wrong” in its evolution; rather, it may be a typical outcome for certain planetary formations. This perspective challenges the assumption that Earth-like conditions are the norm, highlighting that rocky planets might vary widely in their atmospheres.
As we delve deeper into the cosmos, understanding Venus could reshape our views on what makes a planet hospitable—and possibly redefine our expectations for life beyond Earth.
For further details on this study, check out the original conference abstract here.
