yarkovsky effect

The Yarkovsky effect, named after the Polish engineer Ivan Osipovich Yarkovsky who first proposed it in 1900, is a phenomenon that affects the motion of small celestial bodies in the solar system, such as asteroids and meteoroids. This effect arises from the way these objects absorb and re-radiate solar radiation. Here's how it works: Absorption of Solar Radiation: When a small celestial body, like an asteroid, is exposed to sunlight, it absorbs solar radiation and heats up. As it rotates, different parts of the object heat and cool at different times. Re-Radiation of Heat: The object then re-radiates the heat it has absorbed back into space in the form of thermal radiation. The rate at which this heat is re-emitted depends on the object's temperature and its thermal properties. Change in Momentum: As the object re-emits heat in the form of thermal radiation, it also emits photons. These photons carry momentum. When they are emitted in a particular direction, they can impart a tiny force to the object, causing a change in its momentum. Orbital Changes: Over time, this continuous emission and absorption of radiation can cause the celestial body's orbit to change. The Yarkovsky effect can result in changes to the object's semimajor axis, eccentricity, and rotation rate. The Yarkovsky effect is significant for small celestial bodies because they have a relatively low mass and a large surface area relative to their volume. This means that the effect of the radiation can have a measurable impact on their orbits over time. Understanding the Yarkovsky effect is crucial for predicting the future paths of asteroids and other small objects in the solar system. It can influence the likelihood of a collision with Earth and is a factor considered when calculating the long-term orbits of potentially hazardous asteroids. Scientists and astronomers use various methods, including radar observations and thermal modeling, to study and account for the Yarkovsky effect in their predictions.