Explore the Roche limit - the distance where tidal forces disrupt a satellite. Compare fluid (~2.44 R) and rigid (~1.26 R) equal-density limits, then scrub orbital distance in primary radii.
Published teaching figures: fluid Roche factor ~2.44 R, rigid ~1.26 R for equal-density bodies (classic Roche / celestial-mechanics summaries).
Drag to orbit and scroll or pinch to zoom. Scrub distance, switch fluid/rigid mode, or play an inbound approach that crosses the limit.
Roche Limit 3D Explorer
FreetoolOnline editorial teamThe Roche Limit 3D Explorer shows the distance at which a moon is torn apart by tidal forces, as a teaching schematic. A moon outside the limit stays intact; inside it, the scene swaps the sphere for shards. For equal-density bodies the classic fluid factor is about 2.44 primary radii and the rigid approximation about 1.26.
Fluid and rigid limits, and what separates them
The two factors describe two idealizations of the same moon. A fluid satellite deforms as it falls inward and breaks up early, at roughly 2.44 primary radii; a rigid body holds its shape and survives to roughly 1.26 primary radii - so switching the scene from fluid to rigid mode lets an identical moon approach about a full planet radius closer before it disrupts. Saturn's main rings sit inside a fluid-like Roche scale for ice, which is why ring material never gathered into a single moon there. Students see why rings form inside a Roche scale; teachers contrast the fluid and rigid factors; curious readers connect "torn by tides" language to a measurable multiple of planet radius.
What you can do in the scene
- Primary planet with orange fluid (2.44 R) and green rigid (1.26 R) limit rings
- Moon sphere that becomes shards when inside the active limit
- Distance slider in primary radii with play/pause approach
- Fluid / rigid mode toggle
- Distinct from tidal-locking (synchronous spin) and saturn-rings (band radii)
- Runs fully in the browser with the vendored three.js engine - no account, no upload
Key figures at a glance
| Figure | Value | Source note |
|---|---|---|
| Fluid Roche limit | ~2.44 R | Equal-density fluid satellite (classic Roche factor) |
| Rigid Roche limit | ~1.26 R | Equal-density rigid-body approximation |
| Distance unit | primary radii (R) | Slider compares orbit to the chosen factor |
| Density assumption | equal primary / satellite | Teaching simplification; real bodies differ |
Reading the Roche-limit facts panel
The facts panel reports the active fluid and rigid factors alongside your current distance, read straight from the Distance (R) slider. That slider defaults to 3.6 R and ranges from 1.05 R out to 5.5 R in 0.01-R steps, so the current-distance number updates as you scrub. The comparison you actually watch is current distance against the active factor: with the button reading "Mode: fluid 2.44 R", dropping below that ring swaps the moon sphere for shards, and the rigid toggle moves the threshold inward. Press "Play approach" to animate an inbound orbit and watch the current-distance figure fall through whichever limit is active.
Limits of this model
This is an educational Roche-limit schematic, not an N-body hydrodynamics solver: it compares your chosen orbit to a published factor rather than simulating the break-up itself. Everything renders on your device with WebGL; the 3D engine loads once (about 0.7 MB) and is cached, and no scene data is sent to a server.
Related explorers and guide
For the five-step control walkthrough, the sessions this scene suits, and how it differs from its siblings, read when to use Roche Limit 3D Explorer. The Space 3D collection also includes Tidal Locking 3D and Saturn Rings 3D.
Frequently Asked Questions
What does the Roche Limit 3D Explorer show?
A teaching schematic of the Roche limit with fluid (~2.44 R) and rigid (~1.26 R) equal-density markers, a distance slider, and a moon that becomes shards inside the active limit.
What is the fluid Roche factor?
About 2.44 primary radii for an equal-density fluid satellite - the classic Roche teaching figure used in celestial-mechanics summaries.
What is the rigid Roche factor?
About 1.26 primary radii for an equal-density rigid-body approximation. Toggle Mode to compare the green rigid ring with the orange fluid ring.
How is this different from Tidal Locking 3D?
Tidal Locking 3D teaches synchronous spin (one face toward the planet). This page teaches the disruption distance where tides tear a satellite apart.
How is this different from Saturn Rings 3D?
Saturn Rings 3D teaches C/B/A band radii and the Cassini Division. This page teaches why ring material can survive inside a Roche-scale distance.
Is this a hydrodynamics simulation?
No. It is an educational Roche-limit schematic - not an N-body or fluid solver. Densities are equal for the classic 2.44 / 1.26 factors.