The rotation of a Mova globe is driven by magnetism and a photoelectric mechanism powered by light. There are actually two spheres. The outer one is an acrylic shell, inside which a second sphere is suspended in liquid. This inner sphere is covered with a graphic design, such as land masses and water of the Earth. There is about ¼-inch of liquid in between, which has about the same density as the inner sphere, so the interior sphere floats with exactly the same amount of liquid on each side.
A magnet within the inner sphere is aligned with the Earth's real magnetic field. This process is the same as that with a compass. The magnet, in turn, is situated within a photoelectric drive system powered by photovoltaic cells, which are also located inside the inner sphere. The pigment in the graphic design allows light to pass through, which hits the solar cells and allows the mechanism to harvest energy from the light. This energy is used to power the drive mechanism.
The Earth's magnetic field pushes against the magnet, but the Mova globe's drive is able to overcome this inertia and, with even its low power, can drive the higher mass inner sphere. The liquid also minimizes the friction between the two globes. The suspension fluid and outer acrylic shell have optical qualities that make the graphics, painted on the inner globe, look like they are magnified and superimposed on the outer shell. The globe looks like it is spinning on the acrylic stand or supporting surface.
The Mova globe's mechanism is driven by light, so if there is not enough light, it may not rotate or vary in speed while it is rotating. However, exposure to direct sunlight is not recommended. If the globe is exposed to sunlight for too long, it can cause the graphics to fade. Ordinary indoor room light is enough to power a Mova globe. The globe still may not turn correctly, depending on where it is located. Earth's magnetic field is affected by iron girders in large buildings. This can affect the operation of a Mova globe. Proximity to strong magnets, large metal objects or other Mova globes also has an impact on performance. The rotation of the globe can also be affected by rapidly changing lighting conditions. If it is not rotating the proper way, move the Mova globe to another location. Wait a few minutes for it to steady, but if it does not, there may be something in the room inhibiting it.
- bkai: Flickr.com