Frequently Asked Questions

They are slow, predictable changes in Earth’s orbit shape, axis tilt, and axis direction. Together they redistribute incoming sunlight by season and latitude over tens of thousands of years.

Large Northern Hemisphere ice sheets grew around high northern latitudes. If summer there is cool enough that winter snow does not fully melt, snow can accumulate over many years. That makes northern summer sunlight near 65°N a classic indicator of orbital forcing.

No. Eccentricity changes Earth–Sun distance contrast and modulates precession, but its effect on global annual sunlight is small. Ice-age timing emerges from the combined orbital signal and a climate system with ice, ocean, carbon, and other feedbacks.

Earth’s axial precession alone is about 25,772 years. The orbital ellipse also rotates. Their combined climatic precession signal averages about 23,000 years, with important components near 19,000 and 23,000 years.

The Lab defaults to a clearly labeled 5× exaggeration because real changes in eccentricity are nearly invisible on a screen. Choose Actual Scale to see the physical geometry. All numerical calculations always use the real eccentricity.

No. It calculates daily-mean sunlight at the top of the atmosphere for a specific latitude and season. The snow-survival wording is a conditional orbital tendency, not a temperature, ice-volume, or future-climate prediction.

No. Orbital cycles work over tens of thousands of years and cannot explain the speed or pattern of current warming. Today’s rapid warming is driven primarily by human greenhouse-gas emissions.

The four presets use exact nodes from the peer-reviewed La2004 astronomical solution. The Sources page lists the input files, equations, reference values, and limitations.