Earth Versus the Rings of Saturn
Earth as a Saturnian satellite just outside the F ring, ploughing through thousands of icy ring particles and raising wakes, gaps, and density waves.
All Scenarios
3D Space and Gravity Simulator. Simulate the solar system, exoplanets and even colliding galaxies. Add, delete and modify planets, and change the laws of physics.
When Galaxies Collide
Two spiral galaxies on a bound, grazing approach. Tides pull bridges and tails out of their disks as they swing through each other.
Jupiter and the Galilean Moons
Jupiter with Io, Europa, Ganymede, and Callisto — the Galilean moons in 4:2:1 resonance — as a giant-planet satellite system under Newtonian gravity.
Earth with Europa as a Second Moon
Earth with two moons: our Moon plus Europa at 671,000 km (1.7 lunar distances), testing the tidal stability of a double-satellite Earth.
Neptune and Its Moons
Neptune’s moons, dominated by retrograde Triton plus Proteus, Larissa, and highly eccentric Nereid — a captured Kuiper Belt satellite system.
OSIRIS-REx Orbit of Bennu
OSIRIS-REx in orbit around Bennu on 1 August 2019, 1 km from the center, with JPL Horizons states.
The Milky Way and the Magellanic Clouds
The Milky Way with the Large and Small Magellanic Clouds. The Large Cloud is a barred dwarf about 50 kiloparsecs out; the Small Cloud is a looser disk a little farther off, and the two travel together.
Operational Spacecraft at the Moon, 2026
The Moon with five active orbiters — LRO, Chandrayaan-2, Danuri, and ARTEMIS P1/P2 — on 26 September 2026 JPL Horizons states, with Earth and the Sun.
Pluto and Its Moons
Pluto, Charon, Styx, Nix, Kerberos, and Hydra as a binary dwarf-planet system whose barycenter lies outside Pluto, with a 6.4-day mutual orbit.
Sagittarius A*
Sagittarius A*, the 4.28-million-solar-mass black hole at the center of the Milky Way, and twelve S-stars — including S2, S55, and S38 — on orbits from Gillessen et al. (2017), started at S2's 2018 pericenter passage.
Earth–Moon System with Mimas as a Submoon
Mimas as a submoon of our Moon at 7,500 km — well inside the lunar Hill sphere — while the Earth–Moon pair continues its real path around the Sun.
MESSENGER Orbit of Mercury
MESSENGER in orbit around Mercury on 15 March 2013, 10,971 km from the center, with JPL Horizons states.
Saturn and Its Moons
Saturn with Titan, Enceladus, Mimas, and its other major moons, plus thousands of gravitationally interacting ring particles from the D ring to the F ring.
Dancing in a Circle
Four equal masses chasing one another on a shared circular path — a periodic four-body choreography that returns to its starting arrangement instead of flying apart.
The Earth and Moon System
Earth and the Moon as a two-body system: the Moon at 384,400 km, tidally locked on a 27.3-day orbit, with the Sun included as the distant perturber.
Giant Planet in a Debris Ring
A 300-Earth-mass giant at 5 AU inside a 200,000-particle debris ring from 4.5 to 5.5 AU, shepherding material to Lagrange points, collisions, or ejection.
V4641 Sagittarii
V4641 Sagittarii (XTE J1819−254): a 6.4-solar-mass black hole and a B giant on a 2.82-day orbit.
TRAPPIST-1 - System
TRAPPIST-1, seven Earth-sized worlds in a resonant chain around an ultracool dwarf. Several orbit in the habitable zone, closer in than Mercury.