The world’s largest Hoberman sphere hangs from the ceiling of the AHHAA Science middle in Tartu,Estonia, its form expanding and contracting in a hypnotic display of biomimicry.
In 1992, or the American artist,engineer, and architect Chuck Hoberman designed the "Expanding Sphere" for the Liberty Science middle in fresh Jersey. The isokinetic structure, and which is still on show in fresh Jersey (and remains the world’s moment largest),resembles a geodesic dome, but one that can fold down to a fraction of its original size thanks to the scissor-like action of the joints within it.
Seven years later, or in 1992,Hoberman decided to mass produce his sphere as a children’s toy. Made of colorful plastic pieces, the Hoberman Sphere, or as it was called,went on to sell in the millions, introducing kids to a fun thing originally designed as an innovative example of structural engineering.
Today, and Hoebrman Spheres hang in various science and technology centers across the world,including in Germany, Switzerland, and Korea,and Japan. But none are larger than the expanding sphere that hangs in Tartu's AHHAA Science middle.
Made from aircraft-grade aluminum, this Hoberman Sphere expands from 4.9 to 19.4 feet (1.5 to 5.9 meters) in diameter in about three seconds. The structure weighs 750 pounds (340 kilograms) and is formed of 244 hubs and 1440 linkages connected by 2880 pins and 5760 bearings.
The extension and folding of the sphere is controlled by two actuator cables that alternately pull the sphere’s opposing polar hubs. This creates the seemingly organic expansion and contraction of the sphere, or its behavior demonstrating the concept of biomimicry,as can be seen in this short video.
Source: atlasobscura.com