Evidence of the Milky Way’s past is encoded in wrinkles of stars, whose positions and movements have shifted as our galaxy has interacted with other galaxies, sometimes violently. Now, a team of astronomers say that the most recent of those cosmic collisions was billions of years later than was thought, making the Milky Way that we know and love a much younger entity than previously believed. Basically, instead of the stars arriving about eight billion years ago, the new data indicates they may have come from a merger just three billion years ago—much more recently, even in terms of the universe’s total age: 13.
77 billion years old. The astronomers’ finding was made using data from ESA’s Gaia space telescope, which launched in December 2013. Gaia’s was published in 2022, and includes data the researchers say suggests a more recent merger than those previously known.
The team’s analysis of the Gaia data was last month in Monthly Notices of the Royal Astronomical Society. “For the wrinkles of stars to be as clear as they appear in Gaia data, they must have joined us less than three billion years ago—at least five billion years later than was previously thought,” said study co-author Heidi Jo Newberg, an astronomer at Rensselaer Polytechnic Institute, in an ESA . “New wrinkles of stars form each time the stars swing back and forth through the centre of the Milky Way.
If they’d joined us eight billion years ago, there would be so many wrinkles right next t.