When you look up at the night sky, it’s easy to imagine our galaxy as a serene, rotating disc studded with stars. But new discoveries are shattering that tranquil picture: across the expanse of space. hidden in the Milky Way is a colossal wave, rippling outward from the galaxy’s center and tossing whole stars—and even clouds of gas—up and down like cosmic surfers. Thanks to the European Space Agency’s Gaia space telescope, astronomers now realize our home galaxy isn’t just sp
