A remarkably well-preserved, city-sized impact crater on Mars, dubbed a “cosmic butterfly” by scientists, is providing new insights into the planet’s watery past. The crater, located within the geologically active Idaeus Fossae region in the Martian northern lowlands, exhibits a distinctive asymmetrical shape resembling outstretched wings.
The Anatomy of an Unusual Crater
Unlike typical circular impact craters, this formation owes its unique structure to an asteroid striking Mars at an extremely shallow angle. Instead of ejecting debris evenly, the glancing blow flung material outwards in distinct lobes, forming the raised “wings” that span roughly 12.4 miles (20 kilometers) east-to-west and 9.3 miles (15 kilometers) north-to-south—an area comparable to Manhattan Island.
The European Space Agency’s (ESA) Mars Express orbiter, which has been orbiting the planet since 2003, provided the high-resolution topographical data used to create detailed images and simulations of the crater. ESA scientists suggest that the crater’s irregular, walnut-like floor is smoother than its surrounding wings, indicating that impact-induced melting of subsurface ice may have fluidized the ejected material. This suggests that significant quantities of water ice existed beneath the surface at the time of the impact.
Why This Matters: Uncovering Martian Hydrology
The discovery isn’t just about an oddly-shaped crater. It’s about understanding how water existed and moved on Mars, potentially billions of years ago. The uneven distribution of debris suggests a dynamic interaction between the impact energy and the volatile subsurface environment.
This is particularly important because Mars today is a cold, arid world, but evidence increasingly points to a warmer, wetter past. The presence of ancient riverbeds, sedimentary deposits, and now, impact craters that appear to have interacted with subsurface ice, strengthens the case for a more habitable early Mars.
A Recurring Pattern: Other “Animal” Shapes on Mars
This isn’t the first time Mars has revealed geological formations resembling terrestrial life. In 2006, the Mars Express orbiter identified another butterfly-shaped crater in the Hesperia Planum region. NASA rovers have also captured images of rocks that resemble animals—a turtle, coral-like structures, and even “spiders” formed by subsurface ice sublimation.
The prevalence of these shapes is likely a coincidence, but it highlights how our brains are hardwired to recognize patterns, even in random geological formations. More importantly, it underscores the power of orbital and rover data in revealing hidden details about Mars’s surface.
The exact age and size of the impacting asteroid remain unknown. Further analysis may reveal whether fragments of the space rock still reside within the crater. Regardless, the “cosmic butterfly” stands as a striking reminder of the Red Planet’s violent, watery past, offering a glimpse into a Mars that may have once been far more hospitable than it is today.
