Yarkovsky effect

The Yarkovsky effect is a small force on a rotating body caused by uneven emission of absorbed heat. It gradually changes the body's orbit, especially for small asteroids.

Thermal radiation: Electromagnetic radiation emitted by matter because of its temperature. The body loses heat through emitted radiation, whose recoil produces the force.
Near-Earth asteroid: An asteroid whose orbit brings it within 1.3 astronomical units of the Sun. Small near-Earth asteroids can undergo detectable orbital drift from the effect.
Ivan Osipovich Yarkovsky: A Russian civil engineer who proposed a thermal force on rotating celestial bodies in the nineteenth century. His proposal gave the effect its name.
Keplerian orbit: An idealized orbit governed by gravity between two point masses. The effect slowly modifies the orbital elements of an otherwise Keplerian path.
Thermal inertia: A material property describing how slowly its temperature changes in response to heating or cooling. It governs how long surface regions retain heat after moving out of sunlight.
Asteroid orbit determination: The estimation of an asteroid's orbit from observations and dynamical models. Accounting for thermal drift improves orbital estimates over long time spans.
John A. O'Keefe: An American geophysicist who studied how thermal emission affects the rotation of small bodies. His work helped establish the related thermal torque now bearing his name.
Orbital elements: Parameters that specify the size, shape, orientation, and position of an orbit. Thermal recoil changes quantities such as semimajor axis and eccentricity.
Diurnal cycle: A recurring cycle tied to the rotation of a body relative to its illumination. The day-night temperature pattern shifts the time and direction of thermal emission.
Asteroid impact prediction: The assessment of whether an asteroid could collide with Earth and when. Unmodeled drift can alter long-term predictions of an asteroid's impact probability.

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