VSOP (planets) in the context of "Gravitational attraction"

Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The phenomenon is named after the Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he provided a more definitive and quantitative analysis than James Croll's earlier hypothesis that variations in eccentricity, axial tilt, and precession combined to result in cyclical variations in the intra-annual and latitudinal distribution of solar radiation at the Earth's surface, and that this orbital forcing strongly influenced the Earth's climatic patterns.

The secular variation of a time series is its long-term, non-periodic variation (see Decomposition of time series). Whether a variation is perceived as secular or not depends on the available timescale: a variation that is secular over a timescale of centuries may be a segment of what is, over a timescale of millions of years, a periodic variation. Natural quantities often have both periodic and secular variations. Secular variation is sometimes called secular trend or secular drift when the emphasis is on a linear long-term trend.

The term is used wherever time series are applicable in history, economics, operations research, biological anthropology, and astronomy (particularly celestial mechanics) such as VSOP (planets).