Milankovitch cycles

Long-term variations in Earth’s orbital shape, axial tilt, and axial orientation change how sunlight is distributed across seasons and latitudes. These variations help pace glacial and interglacial climate patterns.

Orbital eccentricity: The variation in the shape of an orbit, from nearly circular to more elliptical. Its roughly 100,000-year variations alter how strongly precession changes seasonal sunlight.
Quaternary glaciation: The recurring growth and retreat of large ice sheets during the Quaternary Period. Its repeated glacial-interglacial rhythm is the climatic pattern most closely associated with orbital pacing.
James Croll: A nineteenth-century Scottish scientist who proposed that orbital variations could drive glacial periods. His work linked orbital eccentricity and precession to ice-age climates before modern orbital calculations.
Kepler's laws of planetary motion: Three laws describing how planets orbit the Sun, including their elliptical paths and changing orbital speeds. They provide the orbital geometry underlying eccentricity and seasonal timing.
Solar variation: Changes over time in the Sun’s energy output and magnetic activity. Solar output varies for different reasons and does not explain the characteristic orbital pacing of ice ages.
Axial tilt: The angle between a body's rotation axis and the perpendicular to its orbital plane. Earth’s changing tilt governs the strength of seasonal contrasts, especially at high latitudes.
Glacial period: An interval of colder climate marked by the expansion of continental ice sheets. Reduced high-latitude summer sunlight can limit melting and help ice sheets expand.
Milutin Milanković: A Serbian mathematician who calculated how orbital variations change solar radiation received at different latitudes and seasons. His quantitative calculations gave the cycles their name and a testable climate framework.
Earth's orbit: The path Earth follows around the Sun, shaped by gravitational interactions with other Solar System bodies. Its evolving shape and orientation supply the astronomical variations in the cycles.
Volcanic winter: A period of surface cooling caused by volcanic aerosols reflecting sunlight. Volcanic cooling is abrupt and short-lived compared with orbital cycles spanning thousands of years.

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