Astrojax is a trademark of Active People, Switzerland, for a toy

Toy

A toy is any object that can be used for play. Toys are associated commonly with children and pets. Playing with toys is often thought to be an enjoyable means of training the young for life in human society. Different materials are used to make toys enjoyable and cuddly to both young and old...

 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

Polar moment of inertia

Polar moment of inertia is a quantity used to predict an object's ability to resist torsion, in objects with an invariant circular cross section and no significant warping or out-of-plane deformation. It is used to calculate the angular displacement of an object subjected to a torque...

 of the center ball so it can rotate rapidly in response to torque

Torque

Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

s applied by the string. This prevents the string from snagging or tangling around the center ball.

Roughly, Astrojax play is a cross between juggling

Juggling

Juggling is a skill involving moving objects for entertainment or sport. The most recognizable form of juggling is toss juggling, in which the juggler throws objects up to catch and toss up again. This may be one object or many objects, at the same time with one or many hands. Jugglers often refer...

, yo-yo

Yo-yo

The yo-yo in its simplest form is an object consisting of an axle connected to two disks, and a length of twine looped around the axle, similar to a slender spool...

, and lasso

Lasso

A lasso , also referred to as a lariat, riata, or reata , is a loop of rope that is designed to be thrown around a target and tighten when pulled. It is a well-known tool of the American cowboy. The word is also a verb; to lasso is to successfully throw the loop of rope around something...

. 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.

Astrojax was invented by physics graduate student Larry Shaw in 1987. It first appeared on the market in 1994, when it was sold through The Nature Company

The Nature Company

The Nature Company was a Berkeley, California based chain of retail stores that sold scientific toys, telescopes, artwork and music CDs.The Nature Company was founded in 1972 by Priscilla and Tom Wrubel. Starting from its flagship store on Berkeley's 4th Street, it expanded throughout the United...

, under the name of "Orbit Balls." Over the next several years it won a number of toy awards. In 2000 Astrojax was acquired by Active People, a Swiss company specializing in yo-yo

Yo-yo

The yo-yo in its simplest form is an object consisting of an axle connected to two disks, and a length of twine looped around the axle, similar to a slender spool...

s, juggling toys, kites and open-ended toys such as Bilibo

Bilibo

Bilibo is a magic toy. It is a shell-shaped hard-wearing piece of plastic, produced in six different colors. It was developed in 2001 by Swiss designer Alex Hochstrasser in consultation with experts for child development....

. In 2003 corporate chains such as Target

Target Corporation

Target Corporation, doing business as Target, is an American retailing company headquartered in Minneapolis, Minnesota. It is the second-largest discount retailer in the United States, behind Walmart. The company is ranked at number 33 on the Fortune 500 and is a component of the Standard & Poor's...

, Walmart, KB Toys

KB Toys

K·B Toys was a chain of mall-based retail toy stores in the United States. It was founded in 1922 by the Kaufman brothers. K·B operated 605 stores in 44 U.S. states, Puerto Rico as well as Guam. It was privately held in Pittsfield, Massachusetts...

, and Toys-R-Us started to carry the product.

Active People sells several different types of Astrojax:

• 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.
• The V-max is made from a durable polycarbonate
  Polycarbonate
  PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
  
  . Because of the reduced friction, the V-max is good for faster moves. The V-max is available in a variety of colours, including half-chromed collectors' editions Black Jack, Amber, Lagoon, Snow White, Pachuli and Hyper Frog.
• The Saturn is made from high-quality plastic and has LEDs inside each ball. The LEDs can be set to be constantly on or a strobing, "disco" mode. The standard Saturn has balls with red, yellow and green LEDs. There is also a version with super-bright blue LEDs called the Blue Diamond.
• The liquid-filled aqua has a soft bladder of phthalate-free PVC
  PVC
  Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...
  
   on a hard plastic "vortex." The fluid flows within the bladder dynamically lowering the moment of inertia of the balls.

Astrojax has won a number of toy awards, has been taken into outer space by NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 for their "Toys in Space" program, and there are three Astrojax categories in the Guinness Book of World Records database.

Example Tricks

1. Horizontal Orbit: One of the balls is held in the users hands, the other two hold horizontal orbits underneath. The two spinning balls counterweight each other, maintaining the orbit. This is maintaided by small movements of the top ball to keep the orbits from slowing. The trick can be started by holding both the top and bottom balls (the top one directly below the bottom one), and spinning the middle ball. Then releasing the bottom ball creates a horizontal orbit.

2. Vertical Orbit: Similar to the horizontal orbit, but with the bottom and middle balls orbiting perpendicular to the ground. By tugging slightly on the ball in hand, the orbit continues however long the user desires. This is the starting movement for both tricks.

3. Butterfly: Starting with a vertical orbit the top hand is moved left and right quickly, in time with the rotation of the bottom ball. This causes the balls to move in a shape resembling a helix

Helix

A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...

.

4. Switch: During a vertical orbit the top ball is released and the bottom ball is caught. The orbit now continues with their positions reversed. This trick can be performed repeatedly to add to the effect.

5. Venus: The bottom ball of a vertical orbit is pulled hard so that it travels over the users arm, followed by the middle ball. This trick can also be repeated for added effect.

6. Thriller or "Eskimo Yo-Yo": Hold the middle ball in one hand and start swinging the right ball around it. Then, throw the left ball around and around and watch them swing.