The surface of Venus is scoured with strange, quasi-circular features called coronae. Unlike anything seen on Earth today, they can stretch hundreds of miles in diameter, even going past the thousand mark. Or they can be as little as a few dozen miles across. In images taken from orbit, they look like chaotic scribbles etched into the rock, surrounding a partially collapsed center.<\/p>\n
Large or small, their origins have long been a mystery to planetary scientists. It\u2019s especially puzzling since Venus is a terrestrial world much like Earth, so much so that it\u2019s considered to be our planet\u2019s \u201ctwin,\u201d at nearly the same size and density. We\u2019re also neighbors, putting both worlds at similar distances from the Sun. So why are there coronae all over Venus, but none on Earth?<\/p>\n
A new study<\/a> published in the journal Proceedings of the National Academy of Sciences offers an intriguing explanation \u2014 and it could give us a major clue to how Venus and Earth\u2019s paths diverged. Today, one is dominated by volcanoes with hellish temperatures more than 860 degrees Fahrenheit; the other is a temperate ocean world brimming with life.<\/p>\n \u201cWe get to have this solar system-sized laboratory,\u201d study lead author Madeleine Kerr from the Scripps Institution of Oceanography at UC California, San Deigo, said in a statement<\/a>. \u201cWe have a front row seat to see why these planets are so different.\u201d<\/p>\n The geography of Venus and Earth are fundamentally different in one major way: Venus\u2019s surface is made of a single giant crust, while the Earth is a jigsaw puzzle of moving tectonic plates, which over eons are sucked into the mantle and recycled. But that wasn\u2019t always the case. The Earth got its start as a single unbroken shell, too, and scientists still don\u2019t agree when it first fractured into tectonic plates.<\/p>\n In a sense, Venus, having never grown out of that phase, offers a window into the Earth\u2019s history. Previous research using data from NASA\u2019s Magellan mission suggested that the planet wasn\u2019t as geologically \u201cdead\u201d as once believed, and that the coranae may be evidence of ongoing tectonic activity<\/a>.<\/p>\n One leading theory of corona formation suggests that they\u2019re produced by a blob of hot material from Venus\u2019 mantle bubbling to the surface and pushing against the bottom of the crust.<\/p>\n In this latest study, the researchers built on that idea by mapping the convection of the planet\u2019s mantle, modeling how these bursts of magma travel thousands of miles from the core. Their findings added to the theory that these hot blobs are running into a \u201cglass-ceiling\u201d roughly 400 miles beneath the surface, where the mantle\u2019s shifting crystal structure blocks some of the rising material. So instead of one huge blob, a grapeshot of smaller blobs trickle to the surface, creating the oddly shaped corona. This could also explain why they vary wildly in size.<\/p>\n There\u2019s still a lot of work to be done to verify this hunch, but the researchers think they\u2019re on the verge of a breakthrough akin to how the theory of plate tectonics upended our understanding of Earth\u2019s history in the not-so-distant past.<\/p>\n \u201cThe current state of knowledge of the planet Venus is analogous to the 1960\u2019s pre-plate tectonic era because we currently lack an equivalent unifying theory capable of linking how heat transfer from the planet\u2019s interior gets manifested into the tectonics and magmatic features observed on Venus\u2019 surface,\u201d coauthor David Stegman, a Scripps geophysicist, said in the statement. \u201cWith this new explanation for Venus\u2019 surface features, we feel a revolution has begun and even more exciting discoveries are just around the corner.\u201d<\/p>\n