This past week, a scientific research team led by David Williams of Arizona State University published a new geologic map of Vesta, one of the largest asteroids in our solar system. Using the latest high-resolution images taken by the Dawn spacecraft from 2011 to 2012, they were able to create a detailed image of Vesta’s surface, with all its many peaks and valleys. But the map they produced, which was published in the December issue of the journal Icarus, also tells us much about the asteroid’s long and tumultuous history. The scientists were able to figure out roughly when certain areas of the asteroid’s surface were last modified, by impacts from other objects, for example. The map reads partly like a history for how this crater-covered, potato-shaped rock got the way it is.
Vesta is just 326 miles in diameter, but it is still the second most massive asteroid in our solar system. It has an age of 4.5 million years, and the colored regions in the map above indicate how the asteroid changed during that time. Brown is the oldest area, followed by the purple and light blue regions, which consist of craters caused by massive impacts over one billion years ago. In fact, the potato shape of the asteroid resulted from the shock of these impacts.
Younger than these regions are the light purple and dark blue areas, which consist of the inside areas of the impact basins created by the earlier collisions, which have crumbled and shifted over time. Younger landslides caused changes to the regions marked in green and yellow. In the middle of the map, you can also find the Marcia crater, which was created during the same timeframe by another impact. This crater is part of a series of three craters called “Vesta’s Snowman”, since all three are stacked on top of each other. You can see it more clearly on the photograph of the asteroid below, in the top left.
It just goes to show, an asteroid is much more than just a big boring rock in space. That rock has had a long and vibrant history, and there’s a story behind every crater and mountain. Through satellite imagery, and cartography, we can finally begin to understand this past.