Simulating N-Body Galactic Collisions and NASA TESS Exoplanet Transits in the Browser with WebGPU & WebGL2

Run Cheng — Mon, 26 Oct 2026 10:09:03 GMT

When I launched Space Simulator Online as a zero-install 3D Solar System and night-sky planetarium in raw WebGL2, the most frequent request from physics teachers and students was: "Can we go beyond static Keplerian orbits and interact with real astrophysical dynamics and telescope data in the browser?"

That led to three dedicated interactive labs inside Space Simulator Online:

Galactic Collisions (/galaxies/) — An interactive N-body gravitational simulator accelerated by WebGPU compute shaders (with a WebGL2 fallback) modeling the Milky Way–Andromeda merger and the Antennae Galaxies.
TESS Planet Hunter (/planet-hunter/) — A browser photometry lab where students inspect real NASA TESS light curves to detect exoplanet transits and distinguish them from eclipsing binaries.
Gravitational Waves (/gravitational-waves/) — A real-time 3D binary inspiral and strain waveform visualizer built around LIGO's GW150914 detection, including real-time audio sonification.

Here is how we built the GPU compute pipeline and astronomical data compression to keep the entire experience running at 60 FPS with zero install.

1. N-Body Galaxy Mergers with WebGPU Compute Shaders

In our Solar System view, planets follow analytical Keplerian ellipses evaluated from NASA/JPL Horizons orbital elements. That is O(N) per frame.

A galaxy collision is fundamentally different: as two spiral galaxies pass through each other, tidal tails and bridges emerge from the gravitational interaction of thousands of stellar particles and dark-matter halos. A direct all-pairs gravitational sum scales as O(N^2):

a_i = G * sum_{j != i} m_j * (r_j - r_i) / (||r_j - r_i||^2 + epsilon^2)^(3/2)

Where epsilon is the Plummer softening length that prevents numerical singularities during close stellar passes.

Tile-Based Shared Memory in WGSL

In Space Simulator Online's Galactic Collisions lab, when navigator.gpu is available, we dispatch a WebGPU compute shader with workgroup size 256. Each workgroup loads a tile of particle positions and masses (x, y, z, m) into var sharedTile: array, 256>, synchronizes via workgroupBarrier(), and accumulates accelerations in registers before advancing positions with a symplectic Leapfrog (Kick–Drift–Kick) integrator.

Using a symplectic integrator rather than standard Euler integration preserves phase-space structure so spiral arms and tidal tails remain coherent over hundreds of millions of simulated years.

2. Packing 6,000+ NASA Exoplanets and TESS Transit Light Curves

Our 3D Exoplanet Explorer (/exoplanets/) plots over 6,000 confirmed worlds from the NASA Exoplanet Archive in 3D galactic coordinates derived from Right Ascension, Declination, and Gaia parallax distances.

To let students experience how those planets are discovered, we built Planet Hunter (/planet-hunter/). Instead of synthetic sine waves, it loads real photometric flux time series from NASA's Transiting Exoplanet Survey Satellite (TESS).

When a planet of radius R_p crosses a host star of radius R_*, the fractional drop in brightness gives the transit depth directly:

Delta_F / F = (R_p / R_*)^2

We pre-normalize the PDCSAP flux curves, quantize timestamps and relative flux deltas into compact typed arrays, and render an interactive phase-folding and transit-marking canvas. Students can also compare true planetary transits against classic astrophysical false positives—such as grazing eclipsing binaries and stellar rotation spots.

3. LIGO Strain Waveforms and Web Audio Chirps

Finally, in the Gravitational Waves lab (/gravitational-waves/), we pair a 3D spacetime curvature mesh with the actual Hanford (H1) and Livingston (L1) strain data from GW150914—the first direct detection of two merging black holes (36 and 29 solar masses). Using the browser's AudioContext, you can play the frequency-swept chirp as the orbital separation shrinks toward coalescence.

Try It Live in Your Browser

Everything runs client-side in your browser with no account, no install, and no ads: