4.5-billion-year-old hibonite crystals have shed new light on the earliest days of the Solar System © Field Museum/NASA/ESA/University of Chicago

Crystals trapped in meteorites reveal the Sun’s violent past

4.5-billion-year-old hibonite crystals have shed new light on the earliest days of the Solar System.

The Sun burst into being 4.6 billion years ago, around 50 million years before the Earth formed. This makes studying its early days incredibly difficult, as physical material remaining from this period is scarce. Now, a team from the University of Chicago has found crystals more than 4.5 billion years old buried deep within meteorites that indicate the Sun had a tumultuous early life.

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Prior to the formation of the planets, the Solar System consisted of the Sun surrounded by a massive protoplanetary disc of hot gas and dust that spiralled around it. As this gas and dust cooled down it coalesced into minerals, including the blue hibonite crystals found embedded in meteorites that have landed on Earth.

Upon examining the crystals using a mass spectrometer, the researchers were able to determine that they contained traces of helium and neon, which the team believes would have been created when high energy protons ejected from the young Sun struck the calcium and aluminium atoms within the crystals.

“In addition to finally finding clear evidence in meteorites that disc materials were directly irradiated, our new results indicate that the Solar System’s oldest materials experienced a phase of irradiation that younger materials avoided,” said lead researcher Levke Kööp.

“We think this means that a major change occurred in the nascent Solar System after the hibonites had formed,” he continued. “Perhaps the Sun’s activity decreased, or maybe later-formed materials were unable to travel to the disc regions in which irradiation was possible.”

This is an extract from issue 326 of BBC Focus magazine.

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