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Why do galaxies differ so much in size, shape, composition and activity?

Scientists now estimate that there are over a trillion galaxies in the Universe. Many follow broad classification patterns, but no two are exactly alike. The variety of galaxies we see gives us a picture of a richly differentiated universe. A key question is: why?

Our Work

The physical processes involved in galaxy formation and evolution form an incredibly complex puzzle, operating at a extraordinary scale. Scientists at the Institute for Theory and Computation (ITC) are working on this puzzle by combining simulations with real world observations to piece together the history of the Universe and to predict the fate of galaxies like the Milky Way.

Our Milky Way and the Andromeda Galaxy are giant spiral galaxies hurtling towards each other at 120 kilometers per second. In about 4 billion years, the two will meet. But while galaxies contain stars, gas, dust, and dark matter, they’re mostly empty space. These two ghostly giants will pass through each other, but their gravity will stretch and pull the other until they merge into one massive elliptical galaxy.

Astrophysicists believe that the Sun will be pushed to the outskirts of the new galaxy, known as Milkomeda, with a chance of being ejected into deep intergalactic space.

We see such mergers taking place today. The Antennae Galaxies are two spiral galaxies that have collided, resulting in increased star formation. It is believed that these galaxies will also eventually coalesce into a large elliptical galaxy. By studying the shape and history of galaxies, we are also studying our future.