Stardust inside a meteorite which fell to Earth 50 years ago is thought to be the oldest solid material ever found.
Researchers have worked out that it was formed up to seven billion years ago.
Stars are formed from massive clouds of dust and gas in space.
They can burn for millions of years and then when they 'die' they throw particles - known as stardust - out into space that eventually form new stars, planets, moons and meteorites.
Philipp Heck is a curator at the Field Museum and associate professor at the University of Chicago. He said: "This is one of the most exciting studies I've worked on.
"These are the oldest solid materials ever found, and they tell us about how stars formed in our galaxy."
The materials examined in the study, published in Proceedings of the National Academy of Sciences of the United States of America, are called presolar grains. That means the minerals were formed before the Sun was born.
These presolar grains are very small and rare - they're only found in about 5% of meteorites that have fallen to Earth.
The Field Museum has the largest portion of the Murchison meteorite which fell in Victoria, Australia, in 1969.
Experts studied presolar grains from it, which they managed to separate out from what they described as a "kind of paste" that smells like "rotten peanut butter". Yuck!
Once they had managed to get the presolar grains on their own, the researchers could figure out what type of stars they came from and how old they were.
The researchers learned that some of the presolar grains were the oldest ever discovered on Earth - with some older than 5.5 billion years.
The researchers think that seven billion years ago, there was a bumper crop of new stars forming.
"We have more young grains than we expected," said Professor Heck.
"Our hypothesis is that the majority of those grains, which are 4.6 to 4.9 billion years old, formed in an episode of enhanced star formation.
"There was a time before the start of the Solar System when more stars formed than normal."