Douglas Scott
Professor
University of British Columbia
Yes. Galaxies evolve over long timescales, as they turn their gas into stars, and their constituent parts interact, mainly through gravity. Galaxies also interact with each other, through close fly-bys or even mergers.

Dr. Michael M. Davis
Astronomer
SETI Institute
Good question. We think irregular galaxies have their present shape by chance, and that these evolve over time -- we get a 'snapshot' which does not necessarily represent what we would see a billion years from now.

Yervant Terzian
Professor
Cornell University
Yes, it evolves with time to other shapes due to gravitational effects.

Mordecai-Mark Mac Low
Curator/Professor of Astrophysics
American Museum Natural History
Yes, continually. Galaxies are dynamic objects that evolve under the influence of gravity and gas dynamics. Even spiral and elliptical galaxies change shape. You can see movies of this made from simulations if you look on the web under "galaxy evolution" or "galaxy collisions"

Astronomer*
Yes - gravitational interactions with other galaxies will change its shape over time.

Andrew Liddle
Astronomer
University of Sussex, UK
Yes, individual galaxies settle down to regular shapes. But also galaxies often collide, creating new irregularities. Early on when the Universe was smaller, such collisions were more common.

Karen Vanlandingham
Assistant Professor
Columbia University's Biosphere 2 Center
Yes, but on very long timescales. The shape of all galaxies change on very long timescales due to stellar evolution and interactions between galaxies.

Astronomer*
Yes, galaxies can encounter other galaxies and these encounters can change the shape of a galaxy.

Eilat Glikman
Graduate Student
Columbia University
In many cases the answer is yes. Irregular galaxies usually have their 'irregular' shapes due to tidal forces (gravitational pull on one side more than another) from a larger galaxy. Perfect examples are the Magellanic clouds, satellite galaxies to our own Milky Way. As the Magellanic clouds move around the Milky way, the gravitational force of our own galaxy distorts their shape. In fact the Milky way is gobbling up a small, probably irregular galaxy right now! It is called Sagittarius-A. Once probably pretty normal in shape, it will soon disappear completely into our galactic disk.

Professor*
Yes. Stars are born and die in irregular regions, so the appearance of the visible part of an irregular galaxy certainly changes with time. It can also collide with another galaxy; the result will again look different from what you started with.

Walter Harris
Astronomer
University of Wisconsin-Madison
Yes, a galaxy changes in response to gravity and internal processes. Some galaxies even collide, and this alters their shape dramatically.

Graduate Student*
All galaxies can change their shape when they get too close to other galaxies. This is caused by the gravitational pull of the galaxies on each other. Some galaxies get stretched out, or their shapes change to look more irregular. This happens to irregular galaxies all the time when they get too close to larger galaxies. Other galaxies collide to form new galaxies with new shapes. The favorite example is when two spiral galaxies merge to form an elliptical galaxy.

Ed Churchwell
Professor/Astronomer
University of Wisconsin
Yes, but over a very long time interval. They are rotating and trying to reach an equilibrium (stable, minimum energy) configuration.

Steven Balbus
Astronomy Professor
University of Virginia
Almost certainly...it is evolving by its own gravity.

Professor Rex A. Saffer
Physicist, Astronomer, Educator
Dept. of Astronomy & Astrophysics, Villanova University
Yes - the parts of the galaxy that we are able to see are where stars and glowing gas currently are located. Over time, those stars and gas clouds will run out of fuel or the energy that was making them glow. Then new stars will form and other parts of the galaxy will become bright, changing the way it looks.

Bob Mathieu
Professor of Astronomy
Department of Astronomy, University of Wisconsin - Madison
Yes indeed. For example, the Magellanic Clouds which are orbiting the Milky Way are irregular galaxies that are being stretched by the tides imposed on them by the Milky Way. Eventually they will be torn apart as they merge with the Milky Way.

Martin Duncan
Professor of Physics
Queen's University, Canada
Over very long times (typically millions to billions of years) the shapes can change due either to dynamical instabilities or (more commonly) by interactions (close passages or actual collisions) with other galaxies. Indeed it may be that most elliptical galaxies were formed by the merging of smaller (often) spiral galaxies.

David Batuski
Astronomer
University of Maine
Surely, some of these eventually collapse into more regular shapes.

John Huchra
Astronomer/Professor
Harvard-Smithsonian
Yes. The little puppies evolve dynamically, often because they interact with other galaxies and because the pattern of star formation in them varies with time.

*Respondents opted for anonymity and we respect their wishes.