A team of astronomers found evidence that stars and planets actually grow up together, forming at the same time in a solar system's life.
"We have a pretty good idea of how planets form, but one outstanding question we've had is when they form: does planet formation start early
when the parent star is still growing, or millions of years later?" Amy Bonsor, an astronomer at Cambridge University in the U.K. and lead author of the new research, said in a statement.
Their clues for planets' infancy came from an unexpected place — the dead core of a former sun-like star, known as a white dwarf.
White dwarfs are generally made of only hydrogen and helium, but they can be "polluted" when an asteroid or other rocky body falls into them.
Astronomers can then analyze what the asteroids were made of by looking at the composition of the newly-polluted white dwarf.
Bonsor said, "This is just the beginning,". "Every time we find a new white dwarf, we can gather more evidence and learn more about how planets form."