Mars’s influence on Earth’s climate is far greater than scientists believed just a few years ago. New computer models reveal that this red planet, despite its modest size, actually helps keep Earth’s axis of rotation relatively stable. This discovery upends conventional thinking about how long-term climate cycles form and offers a fresh perspective on the role of our Solar System neighbors.
For a long time, Venus and Jupiter were considered the main ‘conductors’ of Earth’s climate rhythms. Their massive gravitational pull does draw on Earth, triggering the well-known Milankovitch cycles that define glacial and interglacial periods. However, Mars, once seen as a minor player, has unexpectedly taken center stage. It turns out its impact is not only significant, but critical for maintaining our planet’s familiar climate patterns.
Gravitational dance
In their latest study, a team of astronomers from several countries ran a series of sophisticated simulations modeling the behavior of Solar System planets over millions of years. They took turns ‘switching off’ the influence of individual planets to see how Earth’s orbit and tilt would change. When Mars was removed from the equation, two of the three major climate cycles simply disappeared. That means without Mars, Earth could lose its familiar rhythm of alternating glacial eras.
Scientists were particularly struck by the fact that increasing the mass of Mars in simulations led to even greater stabilization of Earth’s axis. The heavier Mars became, the more slowly Earth’s tilt changed, making the climate more predictable. Previously, this effect was attributed exclusively to the Moon, but now it turns out Mars also acts as a ‘stabilizer.’
Fine-tuning Earth’s climate
Earth’s climate is influenced by many factors, and even minor changes in the tilt of its axis or the shape of its orbit can have serious consequences. For example, if Earth’s axial tilt fluctuated as chaotically as Mars’s—where it can shift by tens of degrees—our planet might have become unsuitable for complex life. Until now, it was believed that only the Moon saved Earth from such disasters, but it’s now clear: without Mars, our planet would also be far less stable.
Venus and Jupiter are indeed responsible for the longest and most powerful cycles, but it is Mars that triggers and sustains the shorter, yet equally important rhythms. These cycles affect the distribution of sunlight, the duration of ice ages, and even the evolution of living organisms. Without them, Earth’s history could have taken a very different course.
In Search of New Worlds
The discovery of Mars’ role not only changes our understanding of our own planet, but also our approach to searching for life in the universe. Whereas astronomers once looked for an ‘Earth 2.0’ among planets similar in size and position relative to their star, it’s now clear that the planet’s surroundings are just as important. The presence of a small neighbor on an outer orbit can be crucial for shaping a stable climate.
This means that potentially habitable worlds might not be as rare as once thought. If other systems have Mars-like analogs, they could play the same role as in ours. And that makes the odds of finding life beyond Earth a little higher.
Unanswered questions
Nevertheless, many mysteries remain. What would Earth look like without Mars? Could complex life have developed if climate cycles had disappeared? These questions remain unanswered for now, but new data have already prompted a rethink of many long-held views. Now, astronomers will pay closer attention to the ‘small’ planets on the outskirts of other systems.
The influence of Mars is not just an intriguing scientific detail, but a key to understanding why Earth became the way we know it. And perhaps this is just the beginning of new discoveries about the role cosmic neighbors play in our planet’s fate.
In case you didn’t know, Stephen Kane is a renowned astronomer and professor at the University of California, Riverside, specializing in the study of exoplanets and the dynamics of planetary systems. His research often focuses on the habitability of planets and the search for conditions necessary for life to arise. In recent years, Kane has been actively modeling the impact of various factors on the climate of Earth and other planets, making him one of the leading experts in this field.
