Milky Way shake-up set our galaxy fluttering like a flag

摘要

Our galaxy seems to be more milkshake than Milky Way, opening up a fresh cosmic mystery. The first three-dimensional map of stellar motion in our galactic neighbourhood shows that stars are all shaken up, and hints that the galaxy is undulating like a flag in a breeze. Mary Williams at the Leibniz Institute for Astrophysics Potsdam in Germany and her colleagues combined recently released data about the horizontal speeds of thousands of stars with other readings of how the stars are moving up and down.