Key Points
- Venus likely never had oceans or conditions suitable for life. The study analyzed Venus’s atmospheric chemistry, indicating a dry interior.
- Findings challenge theories of a once-temperate Venus. Results refine the definition of the habitable zone in planetary science.
- NASA’s DAVINCI mission aims to test these conclusions further by the decade’s end.
- The research helps focus exoplanet studies on Earth-like, rather than Venus-like, worlds.
A team of astronomers from the University of Cambridge has concluded that Venus has likely never been a habitable planet, challenging long-held speculations that Earth’s closest planetary neighbor might once have resembled our world. The study, published in Nature Astronomy, analyzed the chemical composition of Venus’s atmosphere and inferred that its interior is too dry to have ever supported the formation of oceans. This finding suggests Venus has been an inhospitable, scorching world throughout history.
The results carry significant implications for the search for life beyond Earth, particularly in narrowing the focus to exoplanets more akin to Earth than Venus. While Venus and Earth share a similar size and rocky composition, their conditions diverge sharply. Venus, with its dense clouds of sulfuric acid and surface temperatures exceeding 500°C, resembles a harsh “evil twin” of Earth. Despite its extreme environment, some researchers have speculated about the possibility of ancient liquid oceans or aerial microbial life in Venus’s thick clouds.
However, the new research casts doubt on these possibilities. Tereza Constantinou, the study’s lead author and a PhD candidate at Cambridge’s Institute of Astronomy, noted that the absence of evidence for past oceans makes it unlikely that Venus ever supported Earth-like life, which depends on the presence of liquid water. This insight refines astronomers’ understanding of the habitable zone—the range of distances from a star where liquid water can exist on a planet’s surface—and highlights the importance of Venus as a boundary for this zone.
Two main theories have sought to explain Venus’s history. The first posits that the planet once had temperate conditions but underwent a runaway greenhouse effect due to extensive volcanic activity. The second suggests that Venus was born hot and has remained unable to sustain liquid water. Using observations of Venus’s atmospheric chemistry, the researchers determined that volcanic gases on Venus contain at most six percent water, reflecting a dehydrated interior. This contrasts sharply with Earth’s water-rich volcanic eruptions.
Future missions like NASA’s DAVINCI aim to confirm these findings by directly exploring Venus’s atmosphere and surface. The study underscores that if Venus has always been inhospitable, similar planets in other star systems are less likely to harbor life, helping astronomers better target their search for habitable worlds.
