New modelling suggests Mars shapes some of Earth’s long-term orbital rhythms, including shorter eccentricity cycles and a 2.4-million-year pattern that vanishes without its gravitational pull.

A study published in Publications of the Astronomical Society of the Pacific says Mars affects several elements of Earth’s Milankovitch cycles, the slow variations in orbit and axial tilt that help steer long-term climate behaviour.

These cycles arise from gravitational exchanges among planets that gradually redistribute how solar energy reaches Earth over tens of thousands of years.

Researchers tested how altering Mars’ mass changes the stability of orbital elements such as eccentricity, perihelion, ascending node and obliquity.

The modelling showed that the 405,000-year eccentricity cycle, largely controlled by Venus and Jupiter, remains stable regardless of Mars’ mass.

But shorter eccentricity cycles of about 100,000 years became increasingly prolonged and pronounced as the red planet’s mass increased, indicating stronger gravitational links among the inner planets.

The team also reported that the 2.4-million-year grand eccentricity cycle disappears entirely if Mars’ mass approaches zero, pointing to a direct dependence on the planet’s gravitational influence.

Scientists involved in the work say the results broaden understanding of how neighbouring planets contribute to climate-forcing patterns and may help identify the masses of Earth-like worlds elsewhere by tracking similar orbital signatures.

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