Data, Accuracy, and Sources

Where the numbers come from, what we compute, and the limits of the data.

137 Finder LLC · Last updated: June 27, 2026

gravityfinder compiles data from public astronomy catalogs and recomputes additional values from it. This page is a short summary of how that data should be understood. The full list of sources, their licenses, and every formula we compute is on our Data and analysis page.

1. Sources and Licenses

Our data comes from public catalogs, each used under its own license and credited accordingly:

NASA Exoplanet Archive: the confirmed exoplanets, host stars, and systems. Public domain; we credit NASA.
OpenNGC: the galaxy catalog. Creative Commons Attribution-ShareAlike 4.0; we attribute the source and acknowledge the share-alike requirement for that data.
Gravitational-Wave Open Science Center (GWOSC): the merging black holes detected by LIGO, Virgo, and KAGRA. Creative Commons Attribution 4.0.
Wikidata: curated facts for individual black holes and notable stars. CC0 (public domain dedication).
Telescope imagery from ESO, ESA/Hubble, NASA, the Event Horizon Telescope, and Wikimedia Commons, used only where the license permits and credited beside each image.
Natural Earth: the coastlines used to draw the Earth in size-comparison illustrations. Public domain.

2. Computed Values Are Ours

Many values on the site are not found in any catalog. We calculate them ourselves from the published parameters above using known, peer-reviewed formulas, and we label the result “computed by gravityfinder.” These include surface gravity and weight, the Earth Similarity Index, habitable-zone classification, travel times, galaxy distances from redshift, and black-hole event-horizon radii. Where a measurement is missing, a minimum, or disputed, we say so or leave it blank rather than guess.

3. Illustrations Are Not Photographs

Most illustrations are generated procedurally from each object’s real measured properties, and are labelled “generated from parameters, not a photograph.” A small number of objects we cannot yet photograph carry an artist’s impression, also clearly labelled. Where we have a real telescope image, we show it and credit the observatory that took it. We never present an illustration as a photograph.

4. Accuracy and Corrections

Astronomical data is uncertain and revised over time, and computed values are only as good as their inputs. Some figures may be wrong, out of date, or only a lower bound. The Service is for informational and educational use and is not an official or scientific record. If you find something that looks wrong, it is a bug and we want to fix it: email support@gravityfinder.com with the page and the detail.