A detailed 3D solar system with 8 planets, major moons, Saturn's iconic rings and the asteroid belt. Realistic orbital periods and inclinations bring the cosmic clockwork to life.
Keplerian orbital mechanics with eccentricity, inclination and true anomaly. Moons orbit their parent planets while the whole system moves together.
Click a planet to focus the camera on it. Zoom in to see moons and rings. Watch the orbital periods — Mercury completes many orbits while Neptune barely moves.
The solar system extends far beyond Neptune. The Oort Cloud, a spherical shell of icy bodies, is thought to reach halfway to the nearest star — about 1 light-year from the Sun.
This interactive WebGL model, built with Three.js, renders the Sun and all eight planets following near-circular Keplerian orbits, complete with major moons, Saturn's rings and a 2,000-particle asteroid belt set between Mars and Jupiter. Each planet sits on an orbit scaled from real semi-major axes, and its angular speed reflects Kepler's third law, so the inner worlds race round while the gas giants barely creep along against a sky of 12,000 procedural stars.
The control panel lets you adjust the Time speed of the whole system, exaggerate Planet size for visibility, toggle the orbit lines and name Labels, recentre the camera on the Sun, and switch on a cinematic Depth of Field blur. You can drag to rotate, scroll to zoom, and click any planet to focus on it. The same orbital mechanics underpin real astronomy: predicting planetary positions, timing Mars launch windows and plotting spacecraft trajectories.
What does this simulation show?
It shows a real-time 3D model of the Solar System: the Sun, the eight planets on their orbits, a selection of major moons, Saturn's rings and the asteroid belt. The whole system moves together so you can watch the relative orbital speeds and zoom in on individual worlds.
How does it decide how fast each planet moves?
Each planet is given an angular speed that follows Kepler's third law, where planets closer to the Sun travel faster. Mercury sweeps around in a fraction of the time Neptune needs for a single lap, mirroring the real ratio of orbital periods.
What do the Time speed and Planet size sliders do?
Time speed multiplies the simulation clock, letting you slow the motion to a crawl or fast-forward many orbits. Planet size scales the rendered radii up or down, which is purely for visibility because true-to-scale planets would be almost invisible at this orbital spacing.
The simulation is governed by Kepler's third law, T squared equals four pi squared over G times M, multiplied by a cubed, where T is the orbital period, a the semi-major axis, M the Sun's mass and G the gravitational constant. As a result orbital speed scales roughly as one over the square root of a.
The orbital order and the relative orbital speeds are realistic, but the planet sizes and the distances between orbits are not to scale. They are compressed and exaggerated so every planet, moon and ring is clearly visible on screen at once, which would be impossible at true astronomical scale.
For visual clarity each planet is placed on a near-circular orbit rather than a true ellipse. Real planetary orbits are mildly elliptical, described by their eccentricity, but at the small eccentricities of most planets the difference is subtle, so circles capture the essential cosmic clockwork without distraction.
Each moon orbits its parent planet on its own pivot while the planet itself orbits the Sun, so the motion is nested. This is why moons such as Earth's Moon, Jupiter's Galilean satellites and Saturn's Titan stay with their planet as it travels around the Sun.
The belt is a field of about 2,000 small particles scattered on a ring between the orbits of Mars and Jupiter, with a little vertical spread. In reality this region holds millions of rocky bodies, remnants of the early Solar System that never coalesced into a planet because of Jupiter's gravity.
The Sun is rendered with a procedural texture, an additive glow sprite and a bloom post-processing pass, giving it a luminous halo. It also acts as the scene's single point light source, so the planets are lit from the centre just as they are in reality, casting their day and night sides.
The same Keplerian mechanics shown here are used by astronomers and engineers to predict where planets will be, to choose efficient launch windows for missions to Mars and beyond, and to plot spacecraft trajectories. Watching the relative speeds builds an intuition for why outer planets have such long years.