Dark Matter Galaxy Rotation Demo
Welcome! The arms of spiral galaxies rotate around their galactic center.
If luminous mass were all the matter, rotation velocities would decrease with distance
from the center (Kepler's Third Law), similar to our Solar System.
However, observations show that rotation curves remain flat or even increase.
This discrepancy suggests the presence of non-luminous matter (dark matter),
particularly in the outskirts of galaxies.
This simulation demonstrates these concepts.
Click 'Begin Demonstration' to see animations and explore the rotation curves.
Animation 1: Luminous Mass Only System
Imagine a galaxy where gravity comes only from visible matter (stars, gas), like our solar system.
Particles further from the center feel a weaker gravitational pull from the enclosed mass and thus orbit slower.
Watch how the outer particles lag behind.
Animation 2: Luminous + Dark Matter System
Now, imagine the same galaxy but with an extensive halo of dark matter.
This additional, invisible mass means that even particles far from the center feel a strong gravitational pull.
Observe how the outer particles can maintain higher speeds, leading to a 'flatter' rotation curve.