A meteorite that hit Australia in 1969 has just been found to contain the oldest substance ever found on Earth.
The rock burst when it first fell, scattering across a five mile radius, and pieces of it were sent to universities and museums worldwide to study.
Now, at the Field Museum in Chicago, some grains in the rock were found to be as old as 7.5 billion years. The grains were once part of a star that was expelled as the star died.
Up until this point, the oldest materials that had been found on earth were dated at around 5.5 billion years.
Researchers with the Field Museum and the University of Chicago, led by Philipp Heck, described their findings in the Proceedings of the National Academy of Sciences journal.
The researchers broke up the meteorite and dissolved it in acid, leaving only the stardust or "pre-solar grains", then determined the date of the particles by measuring their exposure to cosmic rays.
As the pre-solar grains interact with cosmic rays as they move through space, these interactions produce helium and neon atoms, so using the rate of development of these atoms, along with the number of these atoms present inside the grains, the Chicago researchers were able to calculate the the estimated age.
The results suggest evidence for an answer to a long-standing question. Are stars born all over the universe at a steady rate, or are there periods of time where more stars are born more often? Because many of the grains in this meteorite and others belong disportionately to a particular period, it is likely that there was a "boom" in "star births" across the universe at that time.