According to a new study published in Earth & Planetary Science Letters, the surface of Venus may still bear the geological scars of ancient, long-lost oceans that once covered roughly 90 percent of the planet. While scientists have long debated whether Earth’s evil twin was always a hostile world of crushing atmospheric pressure and sulfuric acid clouds, lead researcher Richard Ghail of the University of London and his team argue that Venus once supported oceans and potentially life across most of its surface before succumbing to a runaway greenhouse effect.
Mapping Venus Through Magellan Radar Data
Most available data on the surface of Venus comes from NASA’s Magellan probe, which used radar to map the planet from orbit during the early 1990s. Those radar images revealed a rugged, heavily volcanic world featuring more than 85,000 volcanic features. However, planetary scientists have increasingly questioned whether some of those formations actually share more in common with marine environments than terrestrial lava flows.
Did you know? Venus shares more or less the same size, density, and mineral composition with Earth, yet its surface temperatures are hot enough to melt lead.
Polygonal Fault Systems and Seafloor Sediments
According to the Earth & Planetary Science Letters study, vast terrains crisscrossed by giant polygonal patterns provide the first major clue of ancient water. While previous researchers attributed these fractures to cooling and contracting volcanic rock, Ghail’s team argues they closely resemble polygonal fault systems found in clay-rich marine sediments on Earth. These networks form when thick layers of seafloor mud are buried, compacted, and squeezed like a sponge, developing patterns stretching for kilometers as the sediment shrinks.
Submarine Channels Versus Lava Flows
The second piece of evidence involves enormous channels known as canali. Traditionally interpreted as lava channels, some of these structures stretch for thousands of kilometers—distances that challenge standard models of how far lava can realistically flow. The researchers posit that these formations instead resemble submarine channels on Earth, carved by dense underwater currents. Notably, nearly a third of the polygonal terrains connect to canali that emerge from plains without an obvious volcanic source and terminate in deeper basins.
Ancient Salt Deposits and Lowland Ridges
The third clue centers on wrinkle ridges patterning the Venusian lowlands, which the research team suggests may overlie thick layers of salt left behind by evaporating ancient oceans. On Earth, the Mediterranean Sea deposited vast salt layers during the Messinian Salinity Crisis roughly 5.5 million years ago. Researchers estimate Venus could have produced a salt layer at least 64 meters, or 210 feet, thick—more than enough to deform the overlying crust.
Pro Tip: Upcoming missions like ESA’s EnVision and NASA’s VERITAS will map Venus in far greater detail than Magellan, offering planetary geologists the data needed to test these marine hypotheses.
Frequently Asked Questions
Was Venus always a hostile planet?
Scientists debate whether Venus always featured its current extreme climate, with new research suggesting it may have hosted vast oceans less than a billion years ago.
How much water did ancient Venus hold?
Researchers estimate that an ancient Venusian ocean could have covered 90 percent of the planet’s surface, holding roughly 40 percent as much water as Earth’s oceans.
What missions will study Venus next?
Both the European Space Agency’s EnVision mission and NASA’s VERITAS orbiter are scheduled to study the planet in high-resolution detail.
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