Simple Orbit Simulator vs NearLight

Simple Orbit Simulator brings the elegance of Einstein's general relativity to your fingertips. Watch two celestial bodies dance under the influence of gravity — not as a textbook approximation, but as a true Schwarzschild geodesic simulation — the same physics that governs real planets, stars, and black holes. Real Physics, Visually Beautiful Unlike typical orbit simulators that use Newtonian gravity, Simple Orbit Simulator traces actual curved-spacetime paths. Every orbit is a genuine geodesic of the Schwarzschild metric. The result: Mercury-style perihelion precession that slowly paints a rosette pattern on screen, gravitational time dilation that deepens as the planet plunges toward the star, and event horizon dynamics that are physically meaningful — not just decorative. Black Hole Mode Switch to Black Hole Mode and watch a supermassive compact object warp the simulation. The event horizon, photon sphere, and innermost stable circular orbit (ISCO) become visible boundaries. Push the planet too close and it crosses the point of no return. Accretion disk glow and a dynamically warped spacetime grid make the physics viscerally tangible. Full 3D Orbits Tilt the orbital plane with the inclination slider and drag the canvas to rotate the camera freely. Horizontal drag changes the azimuth — spinning the scene left and right. Vertical drag changes the elevation — from a top-down view to edge-on. A circular orbit becomes an ellipse, a line, or a spiral rosette depending on your viewpoint. Physics is computed in full three-dimensional space. Live Relativistic Metrics Track real-time data as the simulation runs: • Gravitational time dilation factor • Accumulated proper time of the orbiting body • Lorentz gamma factor • Orbital velocity as a fraction of the speed of light • Perihelion precession angle in degrees • Orbits completed Explore and Experiment Adjust star mass, planet mass, and orbital distance with intuitive logarithmic sliders. See how increasing the star's mass deepens the gravitational well. Increase separation and watch relativistic precession shrink as GR effects fade with distance. Combine an inclined orbit with Black Hole Mode for a dramatic 3D plunge trajectory. Built for Clarity Every design decision prioritises understanding over complexity. The simulation uses scaled constants so relativistic effects are visible at screen scale — preserving all qualitative behaviour predicted by general relativity in a form humans can actually see. Simple Orbit Simulator is for students, educators, curious minds, and anyone who has ever looked up at the night sky and wondered what holds it all together.

NearLight is a 3D space simulator that spans the whole journey of an astronomy fan: from a real telescope under tonight's sky to a relativistic starship and the edge of a black hole. Explore the Solar System on exact orbits, fly through 1,000 light-years of real stars, and see with your own eyes what the Lorentz factor does to time. Is your favorite sci-fi movie physically right? Check it. YOUR NIGHT SKY, TONIGHT Step onto a field on Earth and look up: the real sky for your location and moment: by GPS or from an offline catalog of 34,000 cities. Six telescopes stand ready, from a 70 mm beginner refractor to a 12-inch truss Dobsonian, with eight eyepieces, a Barlow, Moon and nebula filters (UHC, OIII), every instrument with its true magnification, field of view, image orientation and brightness. The full Messier catalog is in the sky: over 40 objects as real as astrophotographs at their exact positions and sizes, every object rebuilt from reference photos, 341,000 Tycho-2 stars deep in the field. Light pollution (Bortle scale), atmospheric seeing, twinkling, horizon extinction, even moonlight washing the galaxies out of the eyepiece, this sky behaves like the real one. A Redlight mode protects your dark adaptation. Wind the clock to August 12, 2026 and stand in Iceland or Spain: the total solar eclipse happens with true geometry, corona included. "Tonight's Sky" builds your observing plan, the "Top Objects now" wheel rolls absolute beginners to the ten best sights of the moment and all the Messier objects wait to be discovered, for good. THE SOLAR SYSTEM The Sun, all 8 planets and their major moons on ephemeris-true orbits, validated against JPL data: moon transits and shadow events at the correct times, Saturn's ring shadow, true axial tilts. Classical Spaceflight flies real missions: departure burn, coast, flip, capture burn into orbit, including Voyager-class gravity assists past Jupiter. INTERSTELLAR Search and inspect 8,000+ real stars with names, distances, stellar data, exoplanet hosts and their neighbors within 10 light-years. Plan relativistic journeys in Constant-c or Constant-g mode with acceleration, coast and braking phases. Compare Onboard Travel Time (OTT) with Earth Travel Time (ETT), read the length-contracted distance, peak speed and the energy bill (Joule, TWh, PWh or "Sun-output time"). Ride along in three cameras and near light speed the cockpit shows real relativistic optics: star aberration, Doppler colour shift and beaming. THE WHOLE MILKY WAY Pull back until the galaxy fits on screen: 100,000 light-years across, four spiral arms, the barred core: shaped from the NASA/JPL photograph down to the dust lanes and the red glow of its star-forming regions, with up to 450,000 stars drawn at once. Sol sits where it really does, 27,000 light-years out on its thin local arm. Pick any point and a route runs there from home, telling you the distance, the region you are aiming at: bulge, inner disk, rim and whether you are heading coreward or out. Then fly it, with the same relativistic clocks: a trip to the galactic centre costs a few decades on board and 27,000 years on Earth. BLACK HOLES 70+ known black holes from TON 618 to fictional Gargantua, rendered with a scientific Kerr ray tracer. Change mass and spin, sink toward the event horizon or the innermost orbit, and watch two clocks drift apart: one hour here, seven years on Earth, the Interstellar scenario, on your own screen. 6-DoF navigation: rotate, pinch-zoom, pan on every axis Auto rotation, labels, chase and cockpit cams, one-tap Reset View Ambient space music and living nightscape sounds. Native on Mac, iPad and iPhone. English and German, fully localized including VoiceOver Fully offline: no account, no tracking, and your location never leaves your device.