Galaxy in a Box

Splashery stretches a drumhead over this Splash's outline, twelve inches across, and finds the ways it can ring. Its lowest is 259.4 Hz, 15 cents flat of C4. The next fifteen are its overtones, and each one draws its own figure: sand gathers on the lines that stay still.

Pinch to zoom into the gas; tap to peel the hot gas. Through the telescope, tap for a new exposure.

Galaxy simulations follow gas and stars as particles. These are subsets of three FIRE-2 simulations: a galaxy of roughly the Milky Way's mass today, the same galaxy 10.4 billion years ago, and a dwarf galaxy. They are simulations, not telescope images. Each gas particle is a Gaussian about as wide as its smoothing kernel (the real kernel isn't Gaussian), colored by temperature or density; tap to keep only the cold gas.

Through a telescope (simulated) shows what an observer might record if the galaxy were 160 million light-years away: its star particles, bluer and brighter when young, blurred by the telescope's sharpness, with cold, dense gas dimming them like dust. Choose a filter; each tap starts a new exposure whose grainy photon noise smooths out as light builds up. The colors use a rough rule for how starlight fades with age, so it is a picture to explore, not a measurement.

This link opens it in the Playground. To put it on your own page, add the element and one script tag. Every option.