A gyroscope is a device with a rapidly spinning wheel or circulating beam of light that detects when an object deviates from a desired orientation. French physicist Jean-Bernard-Léon Foucault, who invented the device in the 19th century, mounted a spinning wheel, or rotor, in gimbal rings. The rotor's angular momentum allowed it to maintain its position even when the gimbal assembly tilted. Gyroscopes are designed to resist changes to the direction of their spin axis. They maximize the moment of inertia around the spin axis and spin at the highest possible frequency to maximize angular momentum, which requires greater torque to change direction. Gyroscopes have a variety of applications, including use in compasses, automatic pilots in ships and aircraft, steering mechanisms of torpedoes, and inertial guidance systems in space launch vehicles.

What basic parts make up a gyroscope?

A gyroscope is a device used to detect an object's deviation from a desired orientation. A basic gyroscope consists of a wheel, or rotor , which is mounted on gimbal rings . The spinning rotor's angular momentum allows it to maintain its attitude, even when the gimbal assembly is tilted. One form of gyroscope is a spinning wheel that is mounted so that the direction of its spin axis has universal rotational freedom. The important property of a practical gyroscope is its angular momentum , which is the product of its spin and its inertia about the spin axis.

How does a gyroscope work?

A gyroscope is a device used to detect an object's deviation from a desired orientation, containing either a rapidly spinning wheel or a circulating beam of light. Mechanical gyroscopes operate based on the principle that a spinning rotor maintains its attitude even when its support is tilted. When the support of a spinning wheel is removed from one end, gravity applies a downward force, but the wheel doesn't fall. Instead, the axle rotates horizontally in a counterclockwise direction, known as gyroscopic precession. Gyroscopes resist changes in the direction of their spin axis by maximizing the moment of inertia and spinning at the highest possible frequency. Optical gyroscopes have almost no moving parts and are based on the Sagnac effect, where a beam of light is split and travels in opposite directions around a rotating platform.

What is meant by 'rotation' and 'axis' in a gyroscope?

In a gyroscope , rotation refers to the act or process of spinning around an axis or center. This rotational motion is central to how gyroscopes function. The axis in this context is the straight line around which the gyroscope rotates; it is the axis of rotation . Gyroscopes are designed to resist changes in the direction of their spin axis. They achieve this by maximizing the moment of inertia around the spin axis and spinning at the highest possible frequency. This maximizes the magnitude of the angular momentum, requiring greater torque to alter its direction.

In which devices are gyroscopes commonly used?

Gyroscopes are commonly used in various devices to detect deviations from a desired orientation. These include compasses and automatic pilots on ships and aircraft, as well as steering mechanisms for torpedoes. They are also integral to inertial guidance systems found in space launch vehicles, ballistic missiles, and orbiting satellites. Optical gyroscopes, which have few moving parts, are utilized in commercial jetliners, booster rockets, and orbiting satellites. Additionally, gyroscopes are used for automatic steering and to correct turn and pitch motion in cruise and ballistic missiles. They are also found in stabilized gunsights, bombsights, and platforms that carry guns and radar antennas aboard ships. In aircraft, gyroscopes complement the magnetic compass to provide stable directional information.

How do gyroscopes help keep things balanced and stable?

Gyroscopes help maintain balance and stability by using a spinning wheel or circulating beam of light to detect when an object deviates from its desired orientation. The angular momentum of the spinning rotor allows it to maintain its attitude, even when its base is tilted. Applications of gyroscopes include automatic steering, correcting turn and pitch motion in missiles, and defining direction with accuracy in stabilized gunsights and bombsights. Gyroscopes are also essential in compasses and automatic pilots on ships and aircraft, as well as in the inertial guidance systems of space launch vehicles, ballistic missiles, and orbiting satellites. Optical gyroscopes, with few moving parts, are now used in commercial jetliners, booster rockets, and orbiting satellites.

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Illustration comparing a three-frame gyroscope on the left and a two-frame gyroscope on the right, each with a central spinning wheel mounted in gimbal rings on a stand to demonstrate rotational motion and stability.

Diagram explaining how a gyrocompass works, showing a ship anchored on the equator with a gyroscope whose axis points east and west, and illustrating how Earth's rotation causes the gyroscope's axis to tilt over time, aligning it with true north and south. Includes labeled positions at hourly intervals and a compass rose for orientation.

Diagram of a ring laser gyroscope showing laser beams traveling in a triangular path between three mirrors, with a laser source and a readout sensor to detect interference patterns caused by the Sagnac effect.

A diagram of a gyroscope with a spinning wheel mounted on an angled axis, showing labeled vectors for angular velocity, angular momentum, torque, force of gravity, and the precession direction. Three green axes indicate spatial orientation.

Three-panel diagram illustrating gyroscopic precession: the top panel shows a spinning wheel supported at both ends of its axle, the middle panel shows one support removed, and the bottom panel shows the wheel tilting and precessing while spinning, supported at one end. Axes and rotational directions are labeled throughout.

Figure 3: Rate gyroscopes (Left) Velocity gyro for measuring rate of turn;(right) velocity gyro for measuring rate of roll

Figure 2: Apparent movement of the spin axis of a gyroscope

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Related Topics:: gyrocompass; compass; gimbal; ring laser gyroscope; gyroscope equation

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Oct. 28, 2026 •History

Mechanical gyroscopes

Mechanical gyroscopes are based on a principle discovered in the 19th century by Jean-Bernard-Léon Foucault, a French physicist who gave the name gyroscope to a wheel, or rotor, mounted in gimbal rings. The angular momentum of the spinning rotor caused it to maintain its attitude even when the gimbal assembly was tilted. During the 1850s Foucault conducted an experiment using such a rotor and demonstrated that the spinning wheel maintained its original orientation in space regardless of Earth’s rotation. This ability suggested a number of applications for the gyroscope as a direction indicator, and in 1908 the first workable gyrocompass was developed by German inventor H. Anschütz-Kaempfe for use in a submersible. In 1909 American inventor Elmer A. Sperry built the first automatic pilot using a gyroscope to maintain an aircraft on course. The first automatic pilot for ships was installed in a Danish passenger ship by a German company in 1916, and in that same year a gyroscope was used in the design of the first artificial horizon for aircraft.

Gyroscopes have been used for automatic steering and to correct turn and pitch motion in cruise and ballistic missiles since the German V-1 missile and V-2 missile of World War II. Also during that war, the ability of gyroscopes to define direction with a great degree of accuracy, used in conjunction with sophisticated control mechanisms, led to the development of stabilized gunsights, bombsights, and platforms to carry guns and radar antennas aboard ships. The inertial guidance systems used by orbital spacecraft require a small platform that is stabilized to an extraordinary degree of precision; this is still done by traditional gyroscopes. Larger and heavier devices called momentum wheels (or reaction wheels) also are used in the attitude control systems of some satellites.

Optical gyroscopes

Optical gyroscopes, with virtually no moving parts, are used in commercial jetliners, booster rockets, and orbiting satellites. Such devices are based on the Sagnac effect, first demonstrated by French scientist Georges Sagnac in 1913. In Sagnac’s demonstration, a beam of light was split such that part traveled clockwise and part counterclockwise around a rotating platform. Although both beams traveled within a closed loop, the beam traveling in the direction of rotation of the platform returned to the point of origin slightly after the beam traveling opposite to the rotation. As a result, a “fringe interference” pattern (alternate bands of light and dark) was detected that depended on the precise rate of rotation of the turntable.

Gyroscopes utilizing the Sagnac effect began to appear in the 1960s, following the invention of the laser and the development of fibre optics. In the ring laser gyroscope, laser beams are split and then directed on opposite paths through three mutually perpendicular hollow rings attached to a vehicle. In reality, the “rings” are usually triangles, squares, or rectangles filled with inert gases through which the beams are reflected by mirrors. As the vehicle executes a turning or pitching motion, interference patterns created in the corresponding rings of the gyroscope are measured by photoelectric cells. The patterns of all three rings are then numerically integrated in order to determine the turning rate of the craft in three dimensions. Another type of optical gyroscope is the fibre-optic gyroscope, which dispenses with hollow tubes and mirrors in favour of routing the light through thin fibres wound tightly around a small spool.

This article was most recently revised and updated by Kara Rogers.

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Optical gyroscopes