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🌌 Interactive Spiral Galaxy Rotation Curves

Interactive 3D spiral galaxy where toggling a dark-matter halo on and off shows orbital velocity curves flattening at large radii instead of falling off as visible-matter-only models predict.

Space & Astronomy3DModerate60 FPS

A spiral galaxy of thousands of orbiting stars, where flipping a dark-matter halo on and off changes how fast the outer stars are able to orbit — visible matter alone predicts a falling curve, but a halo keeps it flat.

🔬 What It Demonstrates

Visible-mass-only gravity produces orbital speeds that fall off with radius, just like planets around the Sun. An isothermal dark matter halo adds mass that grows linearly with radius, keeping orbital speed flat — matching real galaxy observations.

🎮 How to Use

Toggle the dark matter halo, adjust its relative mass, change the star count, and speed up or slow down the orbits. Watch the live rotation-curve chart and the disc's outer stars respond in real time.

💡 Did You Know?

Vera Rubin and Kent Ford's rotation-curve measurements in the 1970s provided some of the first strong observational evidence that most of a galaxy's mass is invisible.

⚙ Under the hood

This simulation allows you to visualize and interact with a 3D spiral galaxy, dynamically observing how the addition or removal of a dark matter halo impacts orbital velocities and rotation curves at different radii.

galaxy-rotation-curvesdark-matterastrophysicsorbital-dynamicsastronomy

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install