When galaxies collide, stars seldom crash into each other because they are still separated by enormous distances. But as this Hubble Space Telescope view of NGC 3256 shows, gas and dust in colliding galaxies can come together with spectacular consequences, triggering the formation of vast numbers of new stars and clusters. NGC 3256, located about 100 million light-years from Earth in the constellation of Vela, is the result of the collision of two Milky Way-size galaxies that began about 500 million years ago. It is now an especially luminous starburst galaxy oriented face-on to Earth and showing two distinct nuclei, one of them shrouded by gas and dust, surrounded by more than 1,000 bright star clusters embedded in crisscrossing dust lanes and a large disk of molecular gas. The two galaxies merging in NGC 3256 had similar masses and in a few hundred million years, astronomers say, the two cores will complete the merger to produce a single large elliptical galaxy.
MACS J0717, some 5.4 billion light-years away from Earth in the constellation of Auriga (The Charioteer), is the result of four galaxy clusters colliding. This image is a combination of observations in visible light, X-rays and radio waves from the NASA/ESA Hubble Space Telescope, NASA’s Chandra X-ray Observatory, and the NRAO Jansky Very Large Array.