Expanse — credits and licenses
Game code
Expanse is distributed under the MIT License.
Astronomical data
Star data comes from the HYG Database v4.1 by David Nash, licensed under Creative Commons Attribution-ShareAlike 4.0. Expanse uses a trimmed catalog: stars within 100 parsecs plus naked-eye-visible stars, with selected columns and display names. Positions are converted from parsecs to light-years at runtime. The adapted catalog remains under the same license. See the supplied data license.
3,952 exoplanet host stars that HYG does not contain (TRAPPIST-1, Teegarden's Star and other faint M dwarfs, and the Kepler, K2, TESS and microlensing hosts at any distance) are added from ESA Gaia Data Release 3 (positions, parallaxes, photometry; credit ESA/Gaia/DPAC, CC BY-NC 3.0 IGO) and the NASA Exoplanet Archive (names, identifiers, spectral types). V and B−V magnitudes are converted from Gaia photometry after Riello et al. 2021 (A&A 649, A3) and Pecaut & Mamajek 2013 (ApJS 208, 9); constellations after Roman 1987 (PASP 99, 695). See the extra-star notice.
Nebulae, star clusters and galaxies come from OpenNGC by Mattia Verga, licensed under Creative Commons Attribution-ShareAlike 4.0, with distances from Cantat-Gaudin et al. 2020 (A&A 640, A1), Baumgardt & Vasiliev 2021 (MNRAS 505, 5957), Chornay & Walton 2021 (A&A 656, A110) and the literature cited per object. Expanse uses a selection of objects with added distances; the adapted catalogue remains under the same license. See the deep-sky data sources and license.
The Milky Way backdrop is adapted from The colour of the sky from Gaia's Early Data Release 3 – equirectangular projection, © ESA/Gaia/DPAC, acknowledgement A. Moitinho, licensed under Creative Commons Attribution-ShareAlike 3.0 IGO. It is resampled to 4096×2048 and darkened and rotated to equatorial coordinates in the game; the adapted image remains under the same license. See the image license note.
The dense background star field uses data from the European Space Agency (ESA) mission Gaia (Data Release 3), processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Credit: ESA/Gaia/DPAC. Gaia data are distributed under CC BY-NC 3.0 IGO; Expanse uses a converted subset (positions, magnitudes, colours of ~1.4 million stars). See the Gaia data notice.
Exoplanet data: this research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program (Planetary Systems Composite Parameters table, doi:10.26133/NEA13). Each planet cites its discovery and parameter papers; radii and masses estimated from the other quantity use Chen & Kipping 2017 (ApJ 834, 17). Debris discs are from Pearce et al. 2022 (A&A 659, A135) via the VizieR catalogue access tool, CDS, Strasbourg, France, plus Su et al. 2024 (Vega), MacGregor et al. 2017 (Fomalhaut), Matrà et al. 2019 (β Pictoris) and Backman et al. 2009 (ε Eridani). The adapted tables are licensed CC BY-SA 4.0. See the full source list and survey-limit references.
Pulsars come from the ATNF Pulsar Catalogue (Manchester, Hobbs, Teoh & Hobbs 2005, AJ 129, 1993) and magnetars from the McGill Online Magnetar Catalog (Olausen & Kaspi 2014, ApJS 212, 6); isolated neutron stars and black holes (Gaia BH1–3, Cygnus X-1, V404 Cygni, M87* and others) from the papers cited per object. The compiled table is licensed CC BY 4.0. See the exotic-object sources.
Objects across the Milky Way come from catalogues accessed with the VizieR catalogue access tool, CDS, Strasbourg, France (DOI 10.26093/cds/vizier; Ochsenbein et al. 2000, A&AS 143, 23): open clusters from Hunt & Reffert 2023 (A&A 673, A114), classical Cepheids from Skowron et al. 2019 (Science 365, 478), star-forming regions with maser parallaxes from Reid et al. 2019 (ApJ 885, 131), H II regions from the WISE catalogue of Anderson et al. 2014 (ApJS 212, 1), supernova remnants from Green 2025 (VizieR VII/297) with distances from Ranasinghe & Leahy 2022 and 2023 (ApJ 940, 63; ApJS 265, 53), and young hot stars from Zari et al. 2021 (A&A 650, A112); globular clusters from the Galactic globular cluster database (Baumgardt & Hilker 2018, MNRAS 478, 1520; Baumgardt & Vasiliev 2021, MNRAS 505, 5957; Vasiliev & Baumgardt 2021, MNRAS 505, 5978); pulsars from the ATNF Pulsar Catalogue with YMW16 dispersion-measure distances (Yao, Manchester & Wang 2017, ApJ 835, 29). The compiled tables are licensed CC BY 4.0, except the parts derived from Gaia (open clusters, young stars; credit ESA/Gaia/DPAC, CC BY-NC 3.0 IGO). See the galaxy catalogue sources.
Galaxies beyond the Milky Way come from the 2MASS Redshift Survey (Huchra et al. 2012, ApJS 199, 26) with position angles from the 2MASS Extended Source Catalog (Skrutskie et al. 2006, AJ 131, 1163; Jarrett et al. 2000, AJ 119, 2498), the Updated Nearby Galaxy Catalog (Karachentsev, Makarov & Kaisina 2013, AJ 145, 101), McConnachie 2012 (AJ 144, 4) and Cosmicflows-4 (Tully et al. 2023, ApJ 944, 94), accessed with VizieR and the CDS XMatch service, with names, sizes and orientations from OpenNGC. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The compiled table is licensed CC BY-SA 4.0. See the external-galaxy sources.
The interstellar medium: 3D dust maps of Edenhofer et al. 2024 (A&A 685, A82; Zenodo 10.5281/zenodo.10658339, CC BY 4.0) and Vergely, Lallement & Cox 2022 (A&A 664, A174; CDS J/A+A/664/A174, maps of the EXPLORE project); molecular clouds of Miville-Deschênes, Murray & Lee 2017 (ApJ 834, 57) from the CO survey of Dame, Hartmann & Thaddeus 2001 (ApJ 547, 792); molecular-cloud distances of Zucker et al. 2020 (A&A 633, A51); models of the H I disc (Kalberla & Dedes 2008, A&A 487, 951; Kalberla & Kerp 2009, ARA&A 47, 27) and of the free electrons (YMW16: Yao, Manchester & Wang 2017, ApJ 835, 29); the eROSITA bubbles (Predehl et al. 2020, Nature 588, 227), the Fermi bubbles (Su, Slatyer & Finkbeiner 2010, ApJ 724, 1044) and the Local Bubble (Zucker et al. 2022, Nature 601, 334). The reduced data are licensed CC BY 4.0. See the interstellar-medium sources.
Earth's surface map is NASA's Blue Marble: Next Generation (NASA Earth Observatory, Reto Stöckli), resized for the game.
The other planet, moon and dwarf-planet globes are public-domain maps from NASA and the USGS Astrogeology Science Center: Mercury (MESSENGER — NASA/JHU APL/Carnegie Institution of Washington), the Moon (NASA SVS CGI Moon Kit, LRO LROC), Jupiter (Cassini — NASA/JPL/Space Science Institute, PIA07782), Ceres (Dawn — NASA/JPL-Caltech/UCLA/MPS/DLR/IDA), Io, Europa, Ganymede and Callisto (Voyager and Galileo), Titan (Cassini ISS), Triton (Voyager 2), Pluto and Charon (New Horizons — NASA/JHU APL/SwRI), via USGS Astropedia; Venus (Magellan radar), Mars (Viking), Phobos, Deimos, Saturn and Neptune from NASA 3D Resources. They are resized, re-centred and in places colour-adjusted for the game; NASA and the USGS do not endorse Expanse. See the per-map sources.
Music
“Atlantis” by Jason Shaw (audionautix.com), licensed under Creative Commons Attribution 3.0. See the music credit.
Space recordings and sound effects
The Target panel’s “Listen” clips are real NASA recordings and data sonifications, used under the NASA Images and Media Usage Guidelines; NASA and the Chandra X-ray Center do not endorse Expanse. Only the Mars clip is sound in air; the others are radio or plasma waves turned into audio, or images mapped to sound. Perseverance microphone, Jezero crater, 2021 (NASA/JPL-Caltech); Saturn radio emissions, Cassini RPWS (NASA/JPL/University of Iowa, PIA07966); Jupiter auroral radio and the Ganymede flyby, Juno Waves (NASA/JPL-Caltech/SwRI/Univ. of Iowa, PIA21037, PIA25030); Earth’s chorus, Van Allen Probes EMFISIS (Science@NASA and NASA’s Goddard Space Flight Center); Voyager 1 plasma waves in interstellar space (NASA/JPL-Caltech/University of Iowa, PIA17045); Chandra sonifications of M87 (X-ray: NASA/CXC/KIPAC/N. Werner, E. Million et al.) and the Galactic Centre (X-ray: NASA/CXC/SAO; optical: NASA/STScI; IR: NASA/JPL-Caltech), sonification NASA/CXC/SAO/K. Arcand, SYSTEM Sounds (M. Russo, A. Santaguida).
Sound effects come from Sci-Fi Sounds by Kenney (www.kenney.nl), CC0, and the project’s own. See the per-file audio credits.
Fonts
Rajdhani (Indian Type Foundry) and Share Tech Mono (Carrois Apostrophe), under the SIL Open Font License 1.1 (Share Tech Mono). Arrows, shapes and symbols from a subset of DejaVu Sans (Bitstream Vera licence; DejaVu changes public domain) — see the licence.
Godot Engine
Built with Godot 4.5. The engine and included third-party components retain their respective notices: Godot license and full copyright and third-party notices, copied from the upstream 4.5-stable release source.