YORP effect

The YORP effect is a torque on a small celestial body caused by the uneven emission and reflection of sunlight. It can change the body's rotation rate and, in some cases, its rotational axis.

Yarkovsky effect: A force on a rotating body caused by uneven thermal emission that changes its orbit. Both effects arise from thermal radiation, but this one changes an orbit rather than primarily changing spin.
1998 KY26: A near-Earth asteroid with a rapid rotation period of about 10.7 minutes. Its rapid rotation illustrates the extreme spin states associated with small asteroids and YORP evolution.
David J. Scheeres: An American aerospace engineer whose work helped develop theories of asteroid dynamics and YORP. His analyses helped establish how irregular asteroid shapes experience thermal torques.
Asteroid binary: A system of two asteroids gravitationally bound while orbiting their common center of mass. YORP-driven rotational fission is one route by which binary asteroid systems can form.
Asteroid thermal modeling: The calculation of heat absorption, transport, and emission across an asteroid’s surface. Model choices about roughness and heat flow can change predicted YORP torque.
Thermal inertia: A material’s resistance to changing temperature as it absorbs or releases heat. It controls how delayed heat emission shifts the radiation torque around a rotating body.
54509 YORP: A near-Earth asteroid whose rotation-rate increase provided a landmark YORP detection. Radar observations showed its spin accelerating in the direction predicted by YORP.
Stephen Lowry: A British astronomer who led observations detecting rotational acceleration of asteroid 54509 YORP. His team’s measurements provided the first widely accepted observational detection of YORP.
Asteroid family: A group of asteroids sharing orbital properties and believed to originate from one parent-body collision. YORP can spread family members through space by changing their spin-driven orbital drift.
Asteroid surface roughness: The small-scale texture and irregularity of an asteroid’s surface. Unresolved roughness can modify thermal emission enough to alter torque magnitude or direction.

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