800 million years ago, a catastrophic asteroid breakup rained fire on the inner solar system. This event, as revealed by a new study, had profound implications for the development and evolution of the planets in our solar system, particularly Earth. The study, led by Dr. William F. Bottke from the Southwest Research Institute (SwRI), suggests that the parent body of the Eulalia asteroid family, estimated to be around 100 km in diameter, suffered a catastrophic collision that broke it into thousands of smaller pieces. These fragments were then distributed throughout the inner solar system, leading to a significant asteroidal bombardment that affected the Moon, Earth, Mars, and potentially Venus.
One of the most striking pieces of evidence comes from the Moon. Scientists have noticed a massive uptick in crater formation around 800 million years ago, with the 93 km wide Copernicus crater being a notable example. Samples collected by the Apollo astronauts show that this wasn't an isolated event, as tiny glass beads formed by the intense heat of impacts indicate a clustering of radiometric ages around 800 million years ago. This suggests that the Moon was hit by a barrage of asteroids during this period.
Given Earth's higher gravity, the study posits that for every impact on the Moon, there should be 20 of a similar size on Earth. This hypothesis is supported by the Bitter Springs Anomaly, a dramatic change in Earth's climate marked by huge disruptions to the carbon cycle. The increased amount of asteroid dust in the atmosphere could have contributed to an atmospheric cooling event, which in turn drove some evolutionary diversification of marine life just before the 'Snowball Earth' glaciation period. This theory raises a deeper question about the role of asteroids in the development of life on Earth.
Mars also experienced significant geological changes around 800 million years ago, with a peak in the formation of massive volcanic calderas. The impact shocks from repeated asteroid pummeling could have destabilized Martian magma reservoirs, triggering a planetary surge in volcanic eruptions. Venus, on the other hand, had a more dramatic event approximately 650 million years ago, with the authors speculating that the barrage of asteroid remnants from the Eulalia breakup could have sparked a catastrophic, planet-wide volcanic resurfacing event. This hypothesis, while speculative, is supported by the average surface age of Venus and the use of collisional and dynamical models to reverse-engineer the Eulalia family's history.
The study's findings highlight the critical role of asteroids in the development and evolution of planets. It underscores the importance of understanding the asteroid belt and finding any asteroids that could potentially impact our own planet. As the authors note, this theory drives home just how critical asteroids can be in the development of a planet - and how critical it is that we find any capable of doing that to our own, modern home.
