Tallest and Deepest: Printing Other Worlds

Printing Other Worlds

1The Lakeview Middle School library asked the makerspace club to build a display for its astronomy shelf. Eighth grader Amara Okonkwo had an idea: 3D-print a set of tiles showing famous mountains, volcanoes and canyons from Earth and other worlds, then line them up so visitors could compare them. Her teammate Rafael Duarte pointed out a problem right away. "If we just print what looks cool, the display will tell a false story. The sizes have to come from real data."

2The two students gathered measurements. Heights and depths on Earth come from ground surveys and satellites. For other worlds, the data come from spacecraft. Orbiters around Mars timed laser pulses that bounced off the surface to map the height of the land, and radar on an orbiter mapped Venus through its thick clouds. Different sources give slightly different numbers, so the team rounded each value. On Earth, heights are measured from sea level. Mars, Venus and the Moon have no oceans, so their heights are measured from the average level of each world's surface.

3Next the team chose scales. For heights and depths they used a vertical scale of 1 cm = 2 km. For lengths and widths they used a horizontal scale of 1 cm = 100 km. Rafael worried that using two different scales would make the tiles look stretched, but Amara said one scale would cause a bigger problem, and she planned to explain why on a sign.

4Amara also wanted visitors to see how big each feature is compared with its whole world. She added a table of world diameters and planned a second sign that gives each feature's size as a percent of its world's diameter. "People expect the biggest planet in the display to have the biggest everything," she told Rafael. "Let's see if the numbers agree." They printed a test tile of each feature before starting the final set, and the librarian, Mr. Desmond Pike, agreed to leave the shelf open for a month so classes could visit.