Satellites & Telescopes
Everything on this site was measured by an instrument. These are the ones that did the measuring — what each was built to see, where it sits, and how finely it can resolve.
A field guide to satellites & observatories
Before the catalogue below, a quick tour of the kinds of instruments that watch the sky and the Earth — grouped by the orbit they fly, the way they are built, and the vantage they observe from. Each links out to NASA or Wikipedia if you want to go deeper.
By orbit — where a satellite sits
Roughly 160–2,000 km up. Circles the Earth in about 90 minutes, so it sweeps over a given spot only briefly. Home to the ISS, most Earth-imaging satellites, and Starlink-style constellations because the short distance means sharp images and low signal lag.
Between LEO and the geostationary belt, around 2,000–35,000 km. The classic home of navigation systems — GPS, Galileo and GLONASS all live here, high enough to see a wide swath of the planet at once but low enough to keep signals strong.
A special ring 35,786 km above the equator where a satellite orbits at exactly the speed the Earth turns, so it appears to hang motionless over one spot. Weather and TV-broadcast satellites use it — point your dish once and never move it again.
Orbits that pass near both poles, letting a satellite eventually scan the entire surface as the planet rotates beneath it. Sun-synchronous versions cross each latitude at the same local time every day — ideal for consistent climate and land-survey imagery.
Some missions abandon circular orbits entirely. Highly elliptical orbits linger over high latitudes; deep-space observatories like JWST instead park at a Lagrange point — a gravitational balance spot a million-plus kilometres out where they can stay cold and stable.
By kind — how a satellite is built
Among the earliest designs — giant metallised spheres like Echo 1 (1960) that inflated in orbit and passively bounced radio signals between distant ground stations. Simple, mirror-bright, and visible to the naked eye; a first step before active relay satellites existed.
Miniature satellites built from standardised 10 cm cubes (a '1U' unit). Cheap enough for universities and startups to launch in swarms, they now do real science, Earth imaging and communications that once needed a bus-sized spacecraft.
Relays that receive a signal and re-broadcast it across continents — the backbone of television, phone and internet links. Most sit in the geostationary belt so ground antennas can lock onto a fixed point in the sky.
Satellites that watch the planet rather than the sky: tracking storms, mapping vegetation, measuring sea level and ice. They fly in both geostationary (constant wide view) and polar (detailed full-coverage) orbits depending on the job.
Constellations broadcasting precise time signals; a receiver compares several to fix its position. GPS is the best known, joined by Europe's Galileo, Russia's GLONASS and China's BeiDou.
By vantage — kinds of observatory
Instruments lifted above the atmosphere so the air can't blur or absorb the light. Essential for ultraviolet, X-ray and much infrared astronomy, which never reach the ground. Hubble, Webb and Chandra are all up here for exactly this reason.
Giant mirrors on high, dry mountaintops. They can be far larger than anything launchable, and modern adaptive optics cancel much of the atmosphere's distortion in real time. Keck and the ALMA array are ground-based.
Spacecraft that leave Earth orbit entirely to visit other worlds — orbiting, landing, or sweeping past. Voyager, Juno, Parker Solar Probe and New Horizons carry their instruments to the target instead of watching from afar.
Not one dish but many, linked so their signals combine into the resolving power of a single instrument as wide as the array. ALMA does this with radio dishes; the Event Horizon Telescope spanned the whole planet to image a black hole.
Descriptions are original summaries; follow the links for primary documentation from NASA and Wikipedia.
The instrument catalogue
Individual missions in detail — what each was built to see, where it sits, and how finely it resolves.
Status and specifications reflect published mission information and change over time; follow the mission links for the current picture.
Deck 01 · Real-time orrery
The Solar System in 3D
A live WebGL model — drag to orbit, click any world, and scroll to zoom toward wherever your cursor points. Every planet carries its real inclination, eccentricity and axial tilt, moons circle their planets (watch the Galilean four around Jupiter), the asteroid belt grinds between Mars and Jupiter, and the icy Kuiper Belt — Pluto's home — rings the outer dark. Click either belt for its story.
How big are they, really?
Every world below is drawn to the same scale, smallest first. The orrery above compresses distances to fit them on a screen; this does not compress anything. Hover or tap a world for its size, temperature and air.
The eight planets — and the Sun
The five dwarf planets
Deck 02 · 60,000-star simulation
The Milky Way — You Are Here
Our entire galaxy, charted end to end with 32 real systems and landmarks. Blue markers are our stellar neighborhood; warm gold markers reach across the whole disk — pulsar planets, the bulge worlds Hubble found 27,700 light-years away, the hidden Pistol Star by the core, Omega Centauri up in the halo, and a marker on the mysterious far side of the galaxy explaining why half the map has no names. Scroll to zoom toward your cursor and the disk sharpens into gas clouds and star-forming knots; click any marker for its dossier.
A real photograph of the whole Milky Way, assembled from a dark-sky survey. Credit: ESO/S. Brunier · CC BY 4.0
What you're looking at
That misty band is our galaxy seen edge-on from the inside — we sit within the disk, about 26,000 light-years out, so it wraps the whole sky as a ring. The Milky Way holds 100–400 billion stars in a barred spiral roughly 100,000 light-years across, and the Sun takes about 230 million years to complete one lap. The ancient Greeks called it galaxías kýklos, the "milky circle" — the root of the word galaxy itself.
✦ Chasing dark skies
You can only see the band where the night is dark enough. Roughly 80% of people live under skies too bright to show it. Darkness is rated on the Bortle scale (1 = pristine, 9 = inner city), and dedicated Dark Sky Reserves now protect the best spots. The band rides highest — core and all — on northern summer nights (Jun–Aug) and southern winter; aim for the week around new moon, well after twilight.
// The galaxy holds 100–400 billion stars; NASA estimates at least as many planets. The systems marked here are real, but not to scale.
Deck 03 · Intergalactic space
The Universe at Large
Galaxies are not scattered at random. A few dozen bound together make a group; hundreds to thousands make a cluster; clusters gather into superclusters. On the largest scale everything lines up along the cosmic web — threads of galaxies called filaments, meeting at dense nodes, wrapped around enormous empty voids. Alongside the galaxies sit dark matter, intergalactic gas, quasars and the afterglow of the Big Bang itself. Click anything for its dossier, and zoom in — distant smudges resolve into spiral arms, dust lanes and star-forming knots as you approach.
Seen through real telescopes
The visualiser above is a model. These are photographs — what our instruments actually recorded, and what each one settled.
Deck 04 · The night sky
Constellations — From Where You Stand
Two views of the same sky. First, stand outside on a starry night: drag to look around a full 360° dome built from each star's real celestial coordinates, scroll to zoom, and slide the sky clock to turn the heavens — constellations rise in the east and set in the west, exactly as they do above your head. Click any star for its dossier, and toggle Figures to see the constellation art curved across the dome exactly where the ancients drew it.
// Not every constellation is up at once — that's real. Scorpius rides low in summer skies while Orion rules winter; turn the sky clock to bring each one above the horizon.
// Star colours below are their real observed hues by spectral class, and each disc is sized by the star's true apparent magnitude — the brightest stars are genuinely the biggest dots.
The 88 constellations divide the entire celestial sphere between them — every point in the sky falls inside exactly one, with boundaries fixed by the International Astronomical Union in 1922. Most northern figures come down from Sumerian, Babylonian and Greek tradition; the far-southern ones were charted only after 16th-century sea voyages, which is why they include navigators' instruments and tropical birds. Hydra is the largest and Crux the smallest. Here are the other 56 not individually charted above:
Deck 05 · Extreme objects
Black Holes & Celestial Bodies
Below: a live anatomy of a black hole, built to real Schwarzschild proportions — photon sphere at 1.5 event-horizon radii, disk beginning at the ISCO, the far side of the disk bent up and over the shadow by gravitational lensing, and one limb Doppler-brightened exactly as in the Event Horizon Telescope images. Hover any part to name it, click for its physics, and zoom in — the ergosphere, inner turbulence and singularity only resolve as you approach. Below that, five shelves of the universe's extremes; every card is clickable, with distances, materials, and a link to NASA's real imagery.