About gravityfinder
A relational map of the universe.
Public data · Sources cited · Computed values labeled
gravityfinder is a searchable, deeply cross-linked explorer of the universe. Look up any of the thousands of confirmed exoplanets and you’ll see its host star, its sibling worlds, the nearest systems, what you would weigh standing on it, and how long the trip would take. Open any galaxy to find the black hole at its heart and the famous stars within it.
gravityfinder is built around connections, not lists. Open any world and you can follow it outward, world to star to system to galaxy, one link at a time, instead of paging through a flat directory. A sister site, PolitiFinder, maps U.S. elections the same way.
What we cover
- Exoplanets. More than 6,000 confirmed worlds, with their host stars and the roughly 4,700 systems they live in.
- Galaxies. 10,421, from the Milky Way out across the observable sky.
- Black holes. Supermassive giants at the centres of galaxies, stellar-mass holes, and hundreds caught the moment they merged.
- Notable stars. Famous individual stars in other galaxies, from the most massive star known to the most distant one ever seen.
Where the data comes from
Worlds, stars, and systems come from the NASA Exoplanet Archive. Galaxies come from OpenNGC. The merging black holes come from the Gravitational-Wave Open Science Center (LIGO, Virgo, and KAGRA). Curated facts for the individual black holes and stars come from Wikidata. Each notable star is cited to a primary paper on its own page; each black hole page credits the catalog or observation it comes from, the GWOSC gravitational-wave detections for the mergers and the Event Horizon Telescope imaging for the two we can picture. Photographs come from ESO, ESA/Hubble, NASA, and the Event Horizon Telescope. Each source is public and openly licensed, and reusable from its original provider. The full list of sources, with their licenses, and every formula we compute, is on the data & analysis page.
Three things every page tries to do
- Roam. Follow the connections. From any world, step to its host star, its sibling planets, the nearest systems, and worlds like it, then zoom out to the galaxy and the patch of sky it sits in.
- Feel. Make it human-scale. What you would weigh there, how long a year lasts, how big the sun would look, what colour the sky would be, and how long the journey would take.
- Observe. Bridge to the night sky: whether you could see an object yourself, and what it would take. This part is still being built.
Accuracy first
A site like this is only worth visiting if the numbers hold up. Every value is either a published measurement or something we compute ourselves from public data with a peer-reviewed formula, and we label which is which. Where the data runs out, we leave a blank rather than guess. Most illustrations are drawn from each object’s real measured properties; a few objects we cannot yet photograph carry an artist’s impression, and we never pass off an illustration as a photograph. If you find something that looks wrong, it is a bug, and we want to fix it.
For the curious, students, and educators
gravityfinder is built to be explored and shared. A few ways to use it:
- Bookmark or share anything. Every world, star, galaxy, and black hole has a clean, permanent URL you can hand to a class or drop in a citation.
- Start anywhere. Use search, or the galaxies, black holes, and notable stars hubs.
- Cite us. Suggested form: “gravityfinder.com, accessed [date].”
Who’s responsible
gravityfinder is built and maintained by 137 Finder LLC, a Massachusetts company, the same team behind PolitiFinder. It is held to one standard: show the verifiable number, compute the rest in the open, and cite the source.
Contact
Corrections, data questions, and feedback: support@gravityfinder.com. Spotted a number that looks off? Tell us. Accuracy is the whole point.