About

The application

The Orbit Orchestra visualises thousands of objects currently in Earth orbit (satellites, space stations, and debris) as a real-time three-dimensional scene. Their positions are not streamed live; instead, the application uses the mathematics of orbital mechanics to calculate where each object should be at any given moment, based on periodically updated orbital data.

The result is a kind of silent choreography: the continuous, predictable motion of everything humanity has placed in the sky.

Controls

• Rotate the globe by clicking and dragging.
• Zoom with the scroll wheel or pinch gesture.
• Click any satellite dot or label to open its information panel, showing altitude, speed, orbital period, inclination, NORAD number, launch date, and more. The full orbit path lights up on the globe.
• Search for a specific satellite by name or NORAD catalog number using the search field.

HUD controls

• Groups: select which categories of objects to display. Each group has its own colour.
• Maximum objects: limits how many objects are drawn at once. Lower values improve performance.
• Show names: toggles satellite name labels in the 3D view.
• Show trails: toggles the short comet-tail trails behind each object.
• Time speed: accelerate the simulation. At 10h/s, ten hours of orbital motion play back every second.
• Now: resets the simulation clock to the current real time.
• Altitude: filter objects by orbital zone (LEO, MEO, or GEO+).
• Orbits (the ellipse icon): draws the full orbital path of every visible object.
• Grid (the globe icon): overlays a latitude/longitude graticule with a highlighted equator.
• Map (the map icon): overlays country outlines on the globe.
• Conjunction warnings (the triangle icon): opens the SOCRATES panel showing the top upcoming close approaches between tracked objects over the next 7 days. Click any pair to load both satellites on the globe with their orbit lines highlighted.
• Upcoming launches (the rocket icon): opens a panel listing upcoming space missions with launch status, rocket type, and launch pad. Data is sourced from the KeepTrack launches feed.
• Passes near you (the location pin icon): opens the pass prediction panel. Grant location access or enter coordinates manually to see which satellites will pass overhead in the next 24 hours, in order of time. Use the minimum elevation filter to show only higher, more visible passes. Click any pass to highlight that satellite on the globe in real time; click again to deselect.
• Fullscreen: hides the HUD and fills the screen. The collapsed HUD remains accessible at the lower left.
• Screenshot: saves the current view as a PNG, including any visible name labels, trails, and orbit lines.

Scene

• The lit and dark sides of Earth update in real time based on the actual sun position. The terminator line marks the boundary between day and night.
• The Moon is rendered at its correct orbital position and to scale relative to Earth. Its phase (the lit side) follows from the same sun direction used for Earth's lighting.
• The starfield shows roughly 9,000 stars from the HYG catalog (Hipparcos/Yale/Gliese) in their correct positions, with brightness and colour derived from each star's magnitude and spectral type.

Satellites & orbits

A satellite stays in orbit because it moves fast enough sideways that, as it falls toward Earth, the planet's surface curves away beneath it. The higher the orbit, the slower the required speed, and the longer the orbital period.

Orbits are broadly divided into three zones:

• LEO (Low Earth Orbit), below roughly 2,000 km. Most active satellites live here. The International Space Station orbits at roughly 400 km and completes one revolution every 90 minutes. Starlink, Planet, and most Earth-observation satellites are LEO objects.
• MEO (Medium Earth Orbit), between 2,000 and 35,786 km. Navigation constellations such as GPS, Galileo, GLONASS, and BeiDou occupy this zone. Their higher altitude gives them a wide view of Earth's surface, essential for positioning. Orbital periods range from roughly 4 to 12 hours.
• GEO (Geostationary Orbit), at 35,786 km. At this precise altitude, a satellite's orbital period matches Earth's rotation: 24 hours. It appears to hang motionless above a fixed point on the equator. Most weather and communications satellites use geostationary orbits. Objects above GEO are classified as GEO+ here.

Some orbits are highly elliptical, swinging from a low perigee to a high apogee. The Russian Molniya satellites used such orbits to achieve long visibility windows over high northern latitudes where geostationary orbit is impractical.

A satellite's inclination is the angle between its orbital plane and Earth's equator. An inclination of 0° means the satellite flies directly above the equator; 90° is a polar orbit that passes over both poles; 98° is a sun-synchronous orbit, tilted just past polar so the satellite always crosses the same latitude at the same local solar time.

TLE data and SGP4

Orbital positions in this application are computed from Two-Line Element sets (TLEs): a compact format that encodes the parameters needed to describe an orbit, along with drag and correction terms. TLEs are updated regularly by space-tracking agencies and distributed through services such as the KeepTrack API.

The propagation algorithm is SGP4 (Simplified General Perturbations 4), a mathematical model that accounts for atmospheric drag, Earth's non-spherical shape, and solar/lunar gravitational effects. Given a TLE and a timestamp, SGP4 computes where the satellite is without needing a live telemetry feed.

TLE data ages. A TLE that is several days old will produce a less accurate position, particularly for LEO satellites affected by atmospheric drag. The information panel shows the age of each satellite's TLE.

Groups

Objects are organised into groups based on their function or origin. Each group has its own colour in the visualisation.

Navigation

• GPS: the US Global Positioning System. 31 operational satellites in MEO at roughly 20,200 km.
• Galileo: the European navigation system. 30 satellites in MEO at roughly 23,200 km.
• GLONASS: the Russian navigation constellation. MEO, roughly 19,100 km.
• BeiDou: China's navigation system, with satellites across LEO, MEO, and GEO.
• SBAS: Satellite-Based Augmentation Systems. Geostationary satellites that broadcast corrections to improve GPS accuracy (WAAS, EGNOS, MSAS).
• NNSS / Transit: the US Navy's predecessor to GPS, now retired. Dozens of these early navigation satellites are still tracked in orbit.

Weather & Earth observation

• Weather: a broad collection of meteorological satellites from various agencies.
• NOAA: NOAA's operational weather satellites, including the POES polar orbiters.
• GOES: NOAA's Geostationary Operational Environmental Satellites, positioned above the Americas.
• Sentinel: ESA's Sentinel Earth-observation satellites, used for environmental monitoring, land use, and maritime surveillance.
• LASARSAT: a Search and Rescue technology demonstration satellite, now listed under Science.
• DMC: the Disaster Monitoring Constellation, a group of small satellites for rapid imaging of disaster zones.
• Geodetic: satellites used for precise geodetic measurements of Earth's shape and gravity field.

Communications

• Starlink: SpaceX's broadband megaconstellation. Over 6,000 satellites in LEO, making it by far the largest constellation.
• OneWeb: a LEO broadband constellation providing global internet coverage.
• Iridium: the original Iridium constellation of 66 LEO satellites providing global voice and data coverage, including to polar regions.
• Iridium NEXT: the second-generation Iridium constellation, launched between 2017 and 2019, replacing the original satellites.
• Globalstar: a LEO constellation for satellite phones and IoT data services.
• ORBCOMM: a LEO constellation for machine-to-machine and asset tracking communications.
• Intelsat: one of the largest commercial GEO satellite operators, used for broadcast and data services.
• SES: a Luxembourg-based GEO/MEO operator serving broadcast and broadband markets.
• Eutelsat: a European GEO satellite operator, also expanding into LEO broadband.
• Telesat: a Canadian GEO operator.
• GEO: a general collection of geostationary communications satellites not grouped elsewhere.
• Molniya: Russian satellites in highly elliptical Molniya orbits, designed for coverage of high-latitude regions.
• Qianfan: a Chinese megaconstellation in LEO, developed by Shanghai Spacecom Satellite Technology as a broadband internet network.
• Hulianwang: another Chinese LEO internet constellation, operated under different programmes.
• Kuiper: Amazon's planned LEO broadband constellation, currently in its deployment phase with over 200 satellites launched.

Science

• Science: a broad group of scientific research satellites from NASA, ESA, and other agencies.
• Planet: Planet Labs' constellation of small Earth-imaging satellites (Doves, SkySats).
• Spire: a constellation of small satellites collecting weather, maritime, and aviation data. The group includes both active and decayed satellites; objects marked "Decayed" no longer receive TLE updates and may show very old orbital data.
• TDRSS: NASA's Tracking and Data Relay Satellites, used to relay communications between ground stations and spacecraft such as the Hubble Space Telescope.
• CubeSat: small standardised satellites (typically 10x10x10 cm units) built by universities, companies, and research groups for a wide range of experiments.
• SatNOGS: satellites tracked and supported by the SatNOGS open-source ground station network.
• Radar: radar-imaging satellites used for surface mapping and surveillance regardless of cloud cover or daylight.
• Amateur: satellites built and operated by amateur radio communities worldwide.
• Education: small satellites built by universities and schools as part of educational programmes.
• Engineering: technology-demonstration and experimental satellites testing new components or techniques in orbit.

Special

• Stations: crewed and uncrewed space stations, including the ISS and China's Tiangong.
• Tesla Roadster: a 2008 Tesla Roadster sports car launched atop SpaceX's Falcon Heavy on its maiden flight in February 2018. It remains in heliocentric orbit and is one of the most whimsical objects ever placed in space.
• Military: military satellites from various nations. TLE data for these objects is often withheld or imprecise.
• Westford Needles: tracked remnants of Project West Ford (1963), a US military experiment in which ~480 million copper dipole needles, each 1.78 cm long, were released into orbit to form an artificial ionosphere for communications. Most re-entered the atmosphere; the objects still tracked are clumps of needles that adhered together. At roughly 3,700 km altitude, they may remain in orbit for centuries.
• Visual: objects bright enough to be seen with the naked eye from the ground under good conditions.
• Analyst: objects catalogued as "Unknown" — tracked but unidentified objects in the KeepTrack catalog.
• New (30d): objects launched in the last 30 days.

Debris

These groups contain tracked fragments from specific collision or destruction events. They represent some of the most significant debris-generating incidents in spaceflight history.

• FY-1C debris: fragments from China's 2007 anti-satellite test against the Fengyun-1C weather satellite. One of the largest debris-generating events ever, producing over 3,000 tracked fragments.
• Cosmos-1408 debris: fragments from Russia's 2021 anti-satellite test, which generated over 1,500 tracked pieces and forced the ISS crew to take shelter.
• Iridium-33 debris: fragments from the 2009 collision between Iridium 33 and the defunct Russian Cosmos-2251, the first accidental hypervelocity collision between two intact satellites.
• Cosmos-2251 debris: the other half of the same 2009 collision. Together, Iridium-33 and Cosmos-2251 produced over 2,000 tracked debris objects.

Data sources

Orbital element sets (TLEs) are sourced from the KeepTrack API v4, maintained by Theodore Kruczek. The full catalog (~30,000 objects) is fetched once per hour, parsed from 3-line TLE format, and cached server-side. Individual groups are filtered from this catalog by name, NORAD number, or orbital parameters, and also cached for one hour.

Orbital propagation uses satellite.js, a JavaScript implementation of the SGP4/SDP4 algorithm. Country outlines are from Natural Earth via world-atlas. The 3D globe is rendered with Three.js.

The starfield uses the HYG Database (Hipparcos, Yale Bright Star Catalog, Gliese Catalogue of Nearby Stars), compiled by David Nash. Star positions, magnitudes, and colour indices are drawn from this catalog. Moon position is calculated using a simplified version of the algorithm described in Jean Meeus, Astronomical Algorithms (2nd ed., 1998).