Mars may be smaller than Earth, but it has some surprising effects on our planet’s climate. Recent simulations show that Mars actually influences Earth’s tilt and orbit, contributing to climate cycles that last from hundreds of thousands to millions of years.
For a long time, scientists understood that Earth’s climate is shaped by something called the Milankovitch cycles. These cycles are driven by the gravitational pull of other planets, mainly Venus and Jupiter. Until recently, the exact impact of Mars was unclear. However, researchers like Stephen Kane from the University of California, Riverside, began to dig deeper.
Kane and his team ran simulations that explored how Mars interacts with Earth. Their research revealed that Mars has a more significant impact than previously thought. “I always believed Mars had little influence, but I was surprised by the results,” says Kane.
The Milankovitch cycles control various aspects of Earth’s orbit. These include axial tilt, orbital eccentricity (how oval-shaped our orbit is), and the precession of equinoxes (which affects when Earth is closest to the sun). Some cycles span 430,000 years, primarily influenced by Jupiter and Venus. Interestingly, when Mars was removed from the simulations, two important Milankovitch cycles disappeared.
Kane and his colleagues found that increasing Mars’s mass led to changes in Earth’s tilt. “As Mars gets heavier in our models, the amount of tilt variation decreases,” he explains. This suggests that Mars helps stabilize Earth’s axial tilt, which is critical for creating a stable climate.
While Earth’s tilt varies between 21.5 and 24.5 degrees over 41,000 years, Mars has had a chaotic history, with tilt variations of up to 90 degrees. Previously, scientists thought Earth’s stable tilt was solely due to the moon’s presence. However, this new perspective indicates that Mars also plays a crucial role.
Mars is farther from the sun, which means that its gravitational effects are more pronounced than they would be if it were closer. This means it has a “larger gravitational effect” for its size, as Kane puts it.
These findings may change how astronomers look for potentially habitable exoplanets. Instead of only focusing on Earth-like planets, they should also consider the presence of a stabilizing outer planet.
So, what if Mars didn’t exist? Kane raises an intriguing question: “Without Mars, would Earth’s climate have been stable enough for complex life to evolve?” The answer remains uncertain. But one thing is clear: Mars may be small, but its role in our solar system is anything but minor.
For a deeper dive into these findings, you can view the research published in the Publications of the Astronomical Society of the Pacific.
