Every kind of thing we know of in the universe — and, beside each one, how many this site actually holds.
This page is built straight from the database, every time the site is rebuilt. That is deliberate: a list typed by hand would quietly fall out of step with what the site really contains, and the whole use of a catalogue is to be trusted about what is missing. Where a row says 0, that is a genuine gap, not an oversight in the writing.
Everything held by one ordinary star.
| Kind | What it is | Held | In this site |
|---|---|---|---|
| star | A ball of gas heavy enough to fuse hydrogen in its core. | 8 | Arcturus, Beta Pictoris, Polaris, Proxima Centauri, Sirius, TRAPPIST-1 and 2 more |
| planet | Round, orbits a star, and has swept its orbit clear. | 8 | Earth, Jupiter, Mars, Mercury, Neptune, Saturn and 2 more |
| dwarf planet | Round, but shares its orbit with other rubble. | 5 | Ceres, Eris, Haumea, Makemake, Pluto |
| moon | Orbits a planet rather than the star. | 11 | Callisto, Deimos, Dimorphos, Enceladus, Europa, Ganymede and 5 more |
| asteroid | Rock or metal left over from building the planets. | 5 | Bennu, Didymos, Psyche, Ryugu, Vesta |
| comet | A dirty snowball that grows a tail near the Sun. | 3 | 67P/Churyumov-Gerasimenko, 81P/Wild 2, Halley's Comet |
| belt or cloud | Whole populations of small bodies, not single objects. | 2 | The Asteroid Belt, The Kuiper Belt |
| spacecraft | Ours. The only things on this list we made. | 5 | Hubble Space Telescope, International Space Station, James Webb Space Telescope, Voyager 1, Voyager 2 |
| suspected but unfound | Predicted by the maths; not yet seen. | 2 | Planet Nine (Planet X), The Oort Cloud |
Not held by the Sun at all — born somewhere else, crossing once, gone for good.
| Kind | What it is | Held | In this site |
|---|---|---|---|
| interstellar visitor | Passing through from another star, never to return. | 3 | 1I/'Oumuamua, 2I/Borisov, 3I/ATLAS |
A star's mass at birth decides everything that follows.
| Kind | What it is | Held | In this site |
|---|---|---|---|
| brown dwarf | Too light to ever start fusing. A star that failed to launch. | 1 | Luhman 16 |
| binary star | Two stars orbiting each other. Most stars are in pairs. | 1 | Alpha Centauri A & B |
| star with planets | A star known to have worlds around it. | 1 | The Solar System |
| exoplanet | A planet around another star. | 3 | 51 Pegasi b, Proxima Centauri b, TRAPPIST-1e |
| white dwarf | The bare core a Sun-like star leaves behind, still glowing. | 1 | Sirius B |
| planetary nebula | The shell a dying Sun-like star puffs off. Nothing to do with planets. | 3 | The Dumbbell Nebula, The Helix Nebula, The Ring Nebula |
| cataclysmic variable | A white dwarf stealing gas from a neighbour, flaring as it lands. | 1 | SS Cygni |
| supernova | A star's death explosion, briefly outshining its whole galaxy. | 3 | Kepler's Supernova, SN 1987A, Tycho's Supernova |
| failed supernova | A heavy star that collapses to a black hole and simply goes out, with no explosion at all. | 1 | N6946-BH1 |
| kilonova | Two neutron stars merging. This is where most of the gold in your house was made. | 1 | GW170817 |
| supernova remnant | The wreckage, still expanding centuries later. | 1 | The Crab Nebula |
| neutron star | A city-sized ball so dense a teaspoon weighs as much as a mountain. | 1 | RX J1856.5-3754 |
| pulsar | A neutron star sweeping a beam past us, ticking like a clock. | 1 | The Crab Pulsar |
| X-ray binary | A dead star pulling gas off a living one, glowing in X-rays. | 1 | Sco X-1 |
| stellar black hole | What is left when the heaviest stars collapse. | 1 | Gaia BH1 |
Stars are not born alone, and they do not sit still.
| Kind | What it is | Held | In this site |
|---|---|---|---|
| emission nebula | Gas lit up from inside by the young stars forming in it. | 3 | The Eagle Nebula, The Lagoon Nebula, The Orion Nebula |
| reflection nebula | Dust simply reflecting a nearby star, like fog round a lamp. | 1 | The Witch Head Nebula |
| dark nebula | Dust thick enough to blot out the stars behind it. | 1 | The Coalsack Nebula |
| open cluster | A few hundred young stars, still drifting apart. | 2 | The Beehive Cluster (Praesepe), The Pleiades (Seven Sisters) |
| globular cluster | Hundreds of thousands of ancient stars in a tight ball. | 1 | The Hercules Cluster (M13) |
| OB association | A loose sprawl of hot blue giants, all born together. | 1 | The Scorpius-Centaurus OB Association |
Above the scale of any single star.
| Kind | What it is | Held | In this site |
|---|---|---|---|
| spiral galaxy | A flat disc of stars wound into arms. Ours is one. | 8 | Andromeda Galaxy (M31), Bode's Galaxy (M81), Malin 1, Pinwheel Galaxy (M101), Sombrero Galaxy (M104), The Milky Way and 2 more |
| elliptical galaxy | An old, round swarm with little gas left to make stars. | 2 | Centaurus A (NGC 5128), M87 / Virgo A |
| irregular galaxy | No shape to speak of, usually because something pulled it about. | 1 | Large Magellanic Cloud |
| dwarf galaxy | A small galaxy, often orbiting a bigger one. | 1 | The Sagittarius Dwarf Galaxy and Stream |
| starburst galaxy | Making stars far faster than it can keep up. | 1 | Cigar Galaxy (M82) |
| ring galaxy | A galaxy shot clean through the middle by another. | 2 | Cartwheel Galaxy, Hoag's Object |
| colliding galaxies | Two galaxies in the act of merging. | 1 | The Antennae Galaxies (NGC 4038/4039) |
| supermassive black hole | Millions of Suns' worth, sitting in a galaxy's heart. | 1 | Sagittarius A* |
| quasar | A feeding supermassive black hole, outshining its entire galaxy. | 1 | 3C 273 |
| galactic structure | Parts of a galaxy rather than objects in it: arms, bars, the bulge. | 4 | The Dark Matter Halo, The Galactic Bar and Bulge, The Orion Arm, The Stellar Halo |
Some because nobody has an example; some because the universe has not got round to making one yet.
| Kind | Why not |
|---|---|
| black dwarf | A white dwarf that has finally gone cold and dark. None exist: the universe is nowhere near old enough. |
| magnetar | A neutron star with the strongest magnetic field known. |
| rogue planet | A planet with no star, thrown out of the system it formed in. |
| intermediate black hole | Heavier than a star, lighter than a galaxy's monster. The awkward missing middle. |
Every name in the right-hand column opens that object in Space, where you can travel to it and see what holds it. If you want to know what any of these look like through a real telescope — which is usually far less than the photographs promise — the Planetarium will tell you that, and when to go outside.
tools/build/build_catalog.py from work/build/objects.json. Counts are of objects this site describes, not of objects that exist — there are roughly a hundred billion galaxies, and we name ten.