An unexpected pattern in the motions of the stars in the Milky Way’s disk points to a recent whack from another galaxy.
Two independent groups of astronomers have found a fascinating pattern that reveals itself in the motions of the Milky Way’s stars. The pattern suggests that a neighboring galaxy swept by our own within the last billion years.
The Gaia satellite has provided unprecedented exquisite measurements of the distances and motions to 1 billion stars, providing a high-resolution map of our Galaxy. Since the release of the second data release in April, there has been a deluge of exciting results, ranging from the discovery of new nearby clusters and to the motions of distant galaxies. Now, astronomers are applying the data to our own galaxy.