Astrojax, invented in 1986 by Larry Shaw, is a toy consisting of three balls on a string. One ball is fixed at each end of the string, and the center ball is free to slide along the string between the two end balls. Inside each ball is a metal weight. The metal weight lowers the moment of inertia of the center ball so it can rotate rapidly in response to torques applied by the string. This prevents the string from snagging or tangling around the center ball. Roughly, Astrojax play is a cross between juggling, yo-yo, and lasso. A wide variety of tricks and maneuvers can be performed with it. The basic orbits are vertical orbits, horizontal orbits and a figure-eight (butterfly) pattern. History Astrojax has been used to teach physics at the grade school, high school, and college levels, NASA has taken Astrojax into outer space as part of its Toys in Space education program, and Astrojax has even been the subject of research on nonlinear dynamics, chaos, and the N-body problem on a sphere using sophisticated computer modeling and advanced mathematics. Astrojax can, for instance, be used to demonstrate conservation of angular momentum, how reducing an object's moment of inertia will increase the object's angular velocity, and how the earth's gravity keeps the moon in its orbit. Astrojax was invented by Cornell University physics graduate student Larry Shaw in 1986 while fiddling with hex nuts and dental floss. It first appeared on the market in 1994 as a polyurethane foam version, when it was sold through The Nature Company, under the name of "Orbit Balls." Over the next several years it was sold by New Toy Classics. From 2000 to 2015, Astrojax was licensed by Active People, a Swiss company specializing in yo-yos, juggling toys, kites and open-ended toys such as Bilibo. In 2003 corporate chains such as Target, Walmart, KB Toys, and Toys-R-Us started to carry the product. Several different types of Astrojax were sold by Active People, hentui: The Plus is made of a soft foam and, because of the softness of the balls, is the best version for beginners. It is good for rebound tricks but not particularly showy. It is the same as the version sold by New Toy Classics in the mid-1990s. The V-max is made from a durable polycarbonate. Because of the reduced friction, the V-max is good for faster moves. The