Gravity playground
Set the initial conditions. Let gravity take over.
Current state
| Body | Mass / M☉ | Position / AU (x, y) | Velocity / AU yr⁻¹ (x, y) |
|---|---|---|---|
| A | 1.00 | -0.00000, 0.00000 | 0.00000, -0.00002 |
| B | 3.00e-6 | 1.00000, 0.00000 | 0.00000, 6.28306 |
Model, limits & sources
Planar Newtonian point masses, with mutual gravity and no force softening. This is an idealised experiment, not a Solar System ephemeris. It excludes relativity, physical collisions, tides and gas. The figure eight uses rounded published initial conditions; long-term deviations are possible.
Fixed-step, second-order kick–drift–kick leapfrog. Playback changes viewing speed, never the physics step. Hidden tabs pause; slow devices advance less simulated time rather than taking larger steps. Trails show computed positions only.
G = 39.47692642 AU³ M☉⁻¹ yr⁻² · Δt = 1/8192 yrEnergy drift = |E − E₀| / (K₀ + |U₀|). Angular drift = |Lz − Lz₀| / Σ mᵢ|rᵢ₀||vᵢ₀|, so it remains meaningful when total angular momentum is zero. Low drift is a diagnostic, not a guarantee of trajectory accuracy.
Close encounters stop when a step exceeds 2% of the pair’s gravitational or crossing timescale. Energy drift above 0.1% also stops the run. These are numerical limits, not physical events.
Arrows show velocity; their length represents 0.025 years of unaccelerated displacement.