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Investigating...

Investigating Landforms Investigating Landforms on Venus © 2018 The Regents of the University of California. All rights reserved. Permission granted to purchaser to photocopy for classroom use. Image Credits: (t) NSSDC/NASA; (m) NASA on Venus Imagine traveling in a spaceship toward the surface of the planet Venus. At first, everything is hidden by thick clouds, but as you get closer, This photo, taken by a spacecraft called Venera, you can see the rocky surface below. As you fly shows the rocky surface of Venus. The triangles in over the surface, you notice strange landforms the photo are part of the spacecraft. scattered around. They are raised domes with cracks reaching outward in all directions. These are called novae (NO-vay). Why do we see novae on Venus but not on Earth? Planetary geologist Taras Gerya (TAR‑as GARE-ya) wondered whether two important differences between the two planets might help answer that question. First, Venus’s atmosphere is much thicker than Earth’s. Its thick atmosphere traps heat from the sun, making Venus much hotter than Earth. The average surface temperature of Earth is a Novae are dome-shaped landforms on Venus. comfortable 14°C (57°F), while the average They are easy to see from above because they surface temperature of Venus is a scorching have cracks reaching out from their centers in all 462°C (864°F)! Second, Gerya thought that directions. The word novae is the plural form of possible differences between the geospheres the word nova. of Earth and Venus might affect how novae are formed. He didn’t know for sure, but he thought that the top rock layer on Venus might be thinner than the top layer of Earth’s crust. A thinner crust might allow melted rock called magma to move toward the surface more easily, pushing the surface upward to form the novae. Gerya wanted to test his ideas about how novae form on Venus. But how? Venus is millions of kilometers from Earth, and the novae there were formed millions of years ago. To test his ideas, Gerya made a computer model of Venus. Geologist Taras Gerya built a computer model to test whether the high temperature of Venus’s Models can help scientists like Gerya get surface and the planet’s thin crust make it evidence about things that are difficult or possible for novae to form there. Investigating Landforms on Venus 1 impossible to observe, like the creation of landforms on Venus. Some models are made of physical materials and others run on computers, like Gerya’s Venus model. When Gerya made his computer model, he made it represent Venus in ways that would let him test his ideas. For example, he made the surface temperature of the Venus model much hotter than the surface temperature of Earth. He also made the top rock layer in his model much thinner than the top layer of Earth’s crust. Gerya programmed his model to show what When Gerya ran his model, it showed melted rock Investigating Landforms on Venus © 2018 The Regents of the University of California. All rights reserved. Permission granted to purchaser to photocopy for classroom use.     would happen on Venus over time with this rising up from the mantle, pushing the surface up combination of a high surface temperature and and creating raised domes with cracks spreading a thin rock layer. If features like novae formed in in all directions. his model, he would have evidence that he was right about how novae on Venus were formed. When Gerya ran the model, it showed melted rock rising up from underground, pushing the surface upward and creating raised domes with cracks reaching out in all directions. When he compared the domes that formed in the computer model with the domes on the surface of Venus, he found that the domes in the computer model were the same size and The domes formed in Gerya’s computer model shape as the novae that have been observed (left) were the same size and shape as the novae on the surface of Venus. Because the model found on the real planet Venus (right) Image credit: (b) Earth and Planetary Science Letters 391, pp. 183-192/Elsevier Publishing results matched the real features on Venus, Gerya was more confident that the ideas represented in his model were accurate. 2 Investigating Landforms on Venus