Ceres and Vesta are two of the largest asteroids in the Belt, and their power extends far beyond the band of rocks they inhabit between Jupiter and Mars. Astronomers have discovered that these asteroids' gravitational effects introduced "strong chaos" into the Earth's orbit, making it impossible to know the exact path the Earth took around the sun before 60 million years ago.
This has broad implications for our understanding of Earth life, especially because Earth's orbit is partly what determines weather patterns. Our planet's weather may be have changed a lot more than we thought over time — and could change again in ways we can't predict.
According to a release from Astronomy & Astrophysics, where this discovery was announced:
Ceres and Vesta gravitationally interact together and with the other planets of the Solar System. Because of these interactions, they are continuously pulled or pushed slightly out of their initial orbit. Calculations show that, after some time, these effects do not average out. Consequently, the bodies leave their initial orbits and, more importantly, their orbits are chaotic, meaning that we cannot predict their positions . . . Ceres and Vesta gravitationally interact with the Earth, whose orbit also becomes unpredictable after only 60 million years. This means that the Earth's eccentricity, which affects the large climatic variations on its surface, cannot be traced back more than 60 million years ago. This is indeed bad news for Paleoclimate studies.
It's also bad news for anybody who is trying to understand how climate change works on our planet. If we can't be sure what the planet's orbit was as recently as 60 million years ago, we also can't be sure how close Earth swept past the sun. So we may never know if historical ice ages and thermal maximums were partly caused by asteroids' gravitational meddling.
Write astronomer Jacques Laskar and colleagues:
Ceres and Vesta thus appear to be the main limiting factors for any precise reconstruction of the Earth orbit, which is fundamental for the astronomical calibration of geological timescales. Moreover, collisions of Ceres and Vesta are possible, with a collision probability of 0.2% per Gyr.
That's right — the two biggest asteroids may actually smash into each other at some point. What's the upshot of all this? Life in our solar system is a lot more chaotic than we realized. And our weather may be at the mercy of two distant, misshapen rocks with unpredictable orbits.
Read the full scientific article via Astronomy & Astrophysics
Satellite photo via NASA