Scientists analyzing a meteorite have discovered the oldest material known to exist on Earth, the BBC reports.
They found dust grains within the space rock – which fell to Earth in the 1960s – that are as much as 7.5 billion years old.
The oldest of the dust grains were formed in stars that roared to life long before our Solar System was born.
A team of researchers has described the result in the journal Proceedings of the National Academy of Sciences.
When stars die, particles formed within them are flung out into space. These “pre-solar grains” then get incorporated into new stars, planets, moons and meteorites.
“They’re solid samples of stars, real stardust,” said lead author Philipp Heck, a curator at Chicago’s Field Museum and associate professor at the University of Chicago.
A team of researchers from the US and Switzerland analysed 40 pre-solar grains contained in a portion of the Murchison meteorite, that fell in Australia in 1969.
To work out how old the grains were, the researchers measured how long they had been exposed to cosmic rays in space. These rays are high-energy particles that travel through our galaxy and penetrate solid matter.
Based on how many cosmic rays had interacted with the grains, most had to be 4.6-4.9 billion years old. For comparison, the Sun is 4.6 billion years old and the Earth is 4.5 billion.
However, the oldest yielded a date of around 7.5 billion years old.