Gyroscopes can often seem to defy the laws of physics. However, these devices actually serve as perfect examples of several laws of Physics and play important roles in some of technology’s biggest breakthroughs.

According to the English Oxford Dictionary, a Gyroscope is a “device consisting of a wheel or disc mounted so that it can spin rapidly about an axis which is itself free to alter in direction. The orientation of the axis is not affected by tilting of the mounting.”

While the definition is great, it doesn’t really explain how they work or why they are so important. First, let’s have a look at their ‘strange behavior.’

Gyroscopes are cool things. At first glance, they are pretty strange objects that move in peculiar ways and also seem to “defy” gravity itself. The very special properties of these devices have made them invaluable for navigation among other things.

You’ll find them in airplanes, space stations, and anything that spins really. It’s that phenomena that make gyroscopes so fascinating! A typical airplane will have an entire array of them, including a plane’s all-important compass. The Mir Space Station actually used 11 of them to keep it oriented relative to the sun, plus the Hubble telescope has a batch of them too.

Their ability to seemingly defy gravity is a product of angular momentum, influenced by torque on a disc, like gravity, to produce a precession of the spinning disc or wheel. Well, it’s rotational axis.

The main reason they seem to defy gravity is the effective torque applied to the spinning disc has on its angular momentum vector. The influence of gravity on the plane of the spinning disc causes the rotational axis to “deflect”. This results in the entire rotational axis finding a “middle ground” between the influence of gravity and its own angular momentum vector. Now, remember that the gyroscope apparatus is being stopped from “falling” towards the center of gravity by something in the way — like your hand, the frame/gimbals or a table, for example. Now, factoring in the fact that it is being stopped from “falling” towards the center of gravity by something in the way leads to the fascinating properties we see in these devices.

Scientists tend to use what is called the “right-hand rule” to visualize this.

To do this, take your right hand and make a right angle. Then you can stretch your fingers out along the radius of the wheel. If you curl the end of your fingers in the direction of the spin your thumb will be pointing in the direction of the angular momentum. Basically, the axle of the wheel will be the direction that the entire spinning wheel “wants” to move in.