Venus Polygonal Plains May Point to Watery Past

While Venus is known today as an overwhelmingly inhospitable world, planetary scientists have long debated whether our planetary neighbor once resembled Earth. Observational evidence from billions of years ago hints that Venus might have featured oceans capable of supporting life. Now, fresh analysis of the planet’s surface features is strengthening the case for that watery past.

Cracked Lowland Plains Resemble Ancient Seafloor Mud

Much of the Venusian surface features mysterious networks of cracks. In the planet’s low-lying plains, the ground fractures into distinct polygon shapes that measure roughly 1 to 2 kilometers, or 0.6 to 1.2 miles, across. For decades, researchers assumed these polygon fields formed as hot volcanic rock cooled and contracted.

However, a research team led by Richard Ghail at the University of London took a fresh look at these formations, publishing their findings in Earth and Planetary Science Letters. The team classified the polygon fields into six distinct types based on how the individual cracks are shaped and arranged. Rather than volcanic cooling, the researchers argue that these patterns bear a striking resemblance to cracks found in seafloor mud on Earth. On our planet, thick layers of waterlogged clay get buried, compacted, and squeezed dry over time, eventually shrinking and cracking into polygonal shapes.

Venus May Have Hosted Oceans Across 90% of Its Surface, Study Suggests

Echoes of Earth’s Mediterranean Evaporation History

The idea of drastic planetary drying has a terrestrial parallel. Around 6 million years ago, the Mediterranean Sea almost entirely dried up during an event known as the Messinian salinity crisis. That ancient evaporation left behind thick salt deposits and distinct cracked terrain, which Ghail’s team used as a guide to identify similar features on Venus.

Using this terrestrial event for comparison, the researchers examined long, winding channels called canali on Venus. While these formations are typically assumed to be carved by flowing lava, the team points out their similarity to submarine channels cut by water on ancient seafloors. Additionally, wrinkled ridges crisscrossing the Venusian lowlands could sit on top of thick salt layers left behind after ancient Venusian oceans evaporated.

Marine Hypothesis Awaits Confirmation Through Future Observations

Despite the compelling parallels to Earth’s marine environments, the researchers emphasize that their findings remain a hypothesis rather than definitive proof. Volcanic explanations for the cracks, channels, and wrinkles cannot be ruled out yet, and confirming the marine hypothesis will require much more detailed observations of the Venusian surface.

Even so, the research adds meaningful weight to the theory that Venus once maintained stable oceans and potentially the conditions necessary for life. Beyond shedding light on our nearest planetary neighbor, understanding how Venus lost its water could help scientists determine which distant exoplanets might hold onto moisture. It may also provide a glimpse into the ultimate fate of Earth’s own oceans during the late stages of the sun’s life cycle billions of years in the future.