Such collisions also trigger new star formation. The two groups of stars eventually become a giant elliptical galaxy with no real structure. But when the galaxies are similar in size and mass – like the Milky Way and Andromeda – the close encounter destroys the spiral arm structure. In a galaxy collision, large galaxies absorb smaller galaxies, tearing them apart and incorporating their stars. Since space is really big and the matter in galaxies is spread very thin, this means that actual collisions between individual stars or planets are quite unlikely. The word “collision” is a bit of a misnomer however. They are artificially colored in red and green to make them more visible as they do so. The stars and dust clouds found in galaxies are held together by their mutual gravity as they orbit around a common center – in this simulation, two galaxies are about to collide.
Note: These applications run on Chrome, Edge, recent Safari or Firefox browsers on Mac and PC (but not Windows Explorer). Toggling the Space bar temporarily pauses and un-pauses the simulation (Note: a speed of 1 is extremely slow and may also appear paused). In either simulation view you can use the Simulation Speed slider or the keyboard numbers between 1 and 8 to control the simulation rate depending on the performance of your computer.
Which galaxy keeps its shape better in these different cases? What happens when they are about the same? Try changing the relative mass of the red galaxy to be less than or more than the green galaxy.
Change the parameters as desired then press the Rewind Simulation icon once again to run the full Star and Dust simulation view with those new parameters.Ĭhanging the starting position and velocities of the red galaxy relative to the green galaxy controls the path of the collision or creates a glancing encounter or maybe just a small gravitational interaction instead. Once you are done viewing the current setup from multiple camera positions and want to experiment with the red galaxy’s speed, mass and starting position, click on the Rewind Simulation button once again to get back to the Setup Path (dotted line) view and use the sliders at the upper left to change the starting conditions for the red galaxy (most of these setup slider only appear in this Setup Path view). You can reorient and zoom the cameras by dragging with the mouse right and center button or you can use arrow keys and zoom with the angle bracket keys. Each simulation has 3 camera views tracking the galaxies – one follows the green galaxy center, one follows red, and one deep camera shows both from a long distance away. Use the right mouse and middle mouse buttons to rotate and zoom each view as desired. Each Rewind press alternates between these setup and full star view styles and restarts the collision simulation with the current parameters. The more detailed “Star and Dust” simulation view uses the latest parameters changed in the “Setup Path” view and then rewinds the simulation to use them.
The “Setup Path” view schematically calculates where the red galaxy will go (showing a red disk with the dotted path and orientation indicators).
Each press of the Rewind Simulation icon alternates between a “Setup Path” view and a full “Star and Dust” simulation view. Quick start – try these two icon buttons – try pressing the Rewind Simulation icon (in pink) to restart the current simulation and then press the Switch Camera icon to watch it from three different vantage points (click the Switch Camera icon multiple times to move sequentially between the 3 views).
Galaxy Collision Simulator Instructions