Young star clusters appear as bright blue spots in this scene of two colliding galaxies captured by the Hubble Space Telescope. Released on 21 October by NASA, the image shows that clusters--each containing up to a million stars--can be spawned by the shock waves of a galactic collision. The image supports a long-standing theory that the Antennae, a cosmic object 60 million light-years away, is actually a pair of galaxies in the early stages of a merger. Because the color and brightness of star clusters reveal their ages, astronomers hope to assemble snapshots of the entire collision process from many merging galaxies, using the clusters as "clocks." "It's like watching a car wreck as it happens," says Yale astronomer Steve Zepf.
B. WHITMORE/NASA
Understanding these cataclysms might help shed insight on the early universe, when galaxies were closer together and such events were common. And with the Andromeda galaxy bearing down on the Milky Way at 500,000 km per hour, studies on the Antennae might predict the aftermath of our own cosmic car crash some 5 billion years from now.
