• The classiest Levitron® yet!

• New high-tech design

• Adjustable legs for easy leveling

• The most powerful rare earth magnets available!

• The unique base design amazes onlookers as the high-flying top levitates mysteriously above the opening in the center

What holds the top up? The 'antigravity' force that repels the top from the base is magnetism. Both the top and the heavy slab inside the base box are magnetized, but oppositely. Think of the base magnet with its north pole pointing up, and the top as a magnet with its north pole pointing down (fig 1). The principle is that two similar poles (e.g., two north poles) repel and that two similar poles attract, with forces that are stronger when the poles are closer. There are four magnetic forces on the top: on its north pole, repulsion from the base's north and attraction from the base's south, and on its south pole, attraction from the base's north and repulsion from the base's south. Because of the way the forces depend on distance, the north-north repulsion dominates, and the top is magnetically repelled. It hangs where this upward repulsion balances the downward force of gravity, that is, at the point of equilibrium where the total force is zero.

Why does it need to spin? To prevent the top from overturning. As well as providing a force on the top as a whole, the magnetic field of the base gives a torque tending to turn its axis of spin. If the top were not spinning, this magnetic torque would turn it over. Then its south pole would point down and the force from the base would be attractive - that is, in the same direction as gravity - and the top would fall.  When the top is spinning, the torque acts gyroscopically and the axis does not overturn but rotates about the (nearly vertical) direction of the magnetic field. This rotation is called precession (fig 2). With the LEVITRON®, the axis is nearly vertical and the precession is visible as a shivering that gets more pronounces as the top slows down. The effectiveness of spin in stabilizing a magnetically supported top such as that the LEVITRON® was discovered by Roy M. Harrigan