Astronomers see no stars ejected from the center of our Milky Way galaxy, giving them important information about the Sgr A* black hole.

The Milky Way ripples like a vast cosmic wave. Gaia’s precise measurements reveal a colossal motion sweeping through the galaxy’s disc, an echo of something mysterious in our galaxy’s ancient past.

For decades, astronomers have looked to the outer reaches of the cosmos for answers to our most fundamental questions: Where ...