Atmosfäärikaotust

Atmosfäärikaotust, sometimes referred to as atmospheric escape, is the process by which atmospheric gases escape from a planet's or moon's atmosphere and enter outer space. This phenomenon is driven by the kinetic energy of gas molecules within the atmosphere. If a molecule's velocity exceeds the gravitational escape velocity of the celestial body at its altitude, it can escape. Several factors influence the rate of atmospheric escape, including the body's mass and radius, its atmospheric temperature, and the composition of the atmosphere.

The primary mechanisms of atmospheric escape are Jeans escape and hydrodynamic escape. Jeans escape, named after Sir James Jeans, occurs when individual molecules, particularly lighter gases like hydrogen and helium, gain sufficient thermal energy to overcome gravity. Hydrodynamic escape involves a bulk outflow of atmospheric gases, often driven by strong solar radiation or stellar winds, which heats the upper atmosphere and causes it to expand and flow outward.

Atmospheric escape plays a significant role in the evolution of planetary atmospheres. Over geological timescales, it can lead to the loss of substantial portions of an atmosphere, fundamentally altering the planet's climate and habitability. For instance, it is believed to have contributed to the thinning of Mars' atmosphere over billions of years. Understanding atmospheric escape is crucial for exoplanet research, as it helps scientists assess the potential for life on other worlds by estimating the longevity and composition of their atmospheres.