- Researchers analyzed dust from the asteroid Ryugu to study ancient magnetic forces in the outer solar system.
- Findings suggest a weak but persistent magnetic field influenced the formation of gas giants like Jupiter and Saturn.
- The study challenges previous models, proving magnetic fields played a role even in the distant reaches of the solar nebula.
Did Magnetic Fields Shape the Planets We See Today?
Scientists have long believed that powerful magnetic fields helped shape the inner solar system, guiding dust and gas into forming planets like Earth, Mars, and Venus. But what about the outer solar system, where massive gas giants like Jupiter and Saturn took shape? That question remained a mystery—until now.
A groundbreaking study, published in AGU Advances, reveals that even the outer reaches of the solar system experienced magnetic forces, although much weaker than those near the Sun. The discovery comes from tiny grains of dust collected from the asteroid Ryugu, which traveled billions of miles before being captured by Japan’s Hayabusa2 spacecraft and returned to Earth in 2020.
By studying these ancient particles, researchers from MIT, Caltech, and Harvard found that a weak nebular magnetic field—no stronger than 15 microtesla—existed beyond 7 astronomical units (AU) from the Sun, the region where Jupiter, Saturn, and Neptune formed. This suggests that magnetic forces played a crucial role in shaping the planets even in the farthest reaches of the early solar system.
A Tiny Clue with Big Implications
Scientists used a special instrument called a magnetometer to “rewind” the magnetic history locked inside Ryugu’s grains. Their findings indicate that this faint magnetic field, though weaker than Earth’s current field, helped pull in gas and dust, allowing giant planets to form over time.
One of the most exciting aspects of the study is that it challenges older theories. Previously, many scientists assumed that the outer solar system lacked significant magnetic influence. However, comparisons with other meteorites from the same region show a similar magnetic signature, proving that these forces were present across the solar nebula.
According to planetary scientist Benjamin Weiss, one of the study’s co-authors, “Everywhere we look now, there was some sort of magnetic field that played a role in forming planets.”
This discovery not only sheds light on the birth of our solar system but also helps scientists understand how planetary systems might form around other stars in the universe.
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