Attribution

Data attribution

Meteor showers

meteor-showers.json holds the radiant and peak solar longitude of every shower the IAU classes as established, from:

IAU Meteor Data Center — established meteor showers (V.2)

https://www.ta3.sk/IAUC22DB/MDC2022/

Maintained at the Astronomical Institute of the Slovak Academy of Sciences

No licence is stated and citation is requested. The database's own header names the papers to cite, and they are reproduced in the JSON and here:

- Jenniskens, P.; Jopek, T.J.; Janches, D.; Hajdukov�. M.; Kokhirova, G.I.; Rudawska, R; 2020, Planetary and Space Science, Vol. 182, article id. 104821

- Jopek, T.J.; Kanuchova, Z.; 2017, Planetary and Space Science, Volume 143, p. 3-6

- Jopek, T.J.; Kanuchova, Z.; 2014, in The Meteoroids 2013, Proceedings of the Astronomical Conference held at A.M. University, Poznan, Poland, Aug. 26-30, 2013, Eds.: T.J. Jopek, F.J.M. Rietmeijer, J. Watanabe, I.P. Williams, A.M. University Press, 2014, p. 353-364

- Jopek, T.J.; Jenniskens, P.M.; in Meteoroids: The Smallest Solar System Bodies, Proceedings of the Meteroids Conference held in Breckenridge, Colorado, USA, May 24-28, 2010. Edited by W.J. Cooke, D.E. Moser, B.F. Hardin, and D. Janches, NASA/CP-2011-216469., p. 7-13

The MDC's own file carries a replacement character where the fourth author of the 2020 reference should read Hajduková; the text is reproduced as published rather than corrected in place.

Each shower additionally carries the reference for its *own* solution, because a shower has one record per published determination and the one kept here is whichever rests on the most meteors. Radiant coordinates and solar longitudes are measurements rather than expression.

There is no zenithal hourly rate in this file and none is added. ZHR is an observational quantity from the IMO's visual network, not an MDC field. What the interface shows instead is computed for the reader: how high the radiant climbs in darkness from their own latitude, and what the Moon is doing that night.

Deep-sky objects

dso.json is a filtered subset of:

HYG Database — misc/dso.csv, David Nash / astronexus

https://github.com/astronexus/HYG-Database

Licensed CC BY-SA 2.5

Note the version. The star tiers below are CC BY-SA 4.0; the deep-sky file in the same repository carries its own licence file and it is 2.5. Both are share-alike, so dso.json is a derived work under the same obligation, but the difference is worth keeping straight rather than rounding off.

609 objects from 227,285: every Messier, plus NGC and IC brighter than magnitude 10. Rows the source flags as duplicates are dropped on its own instruction.

Star catalogue attribution

The binary star tiers in this directory (hyg-t0.bin, hyg-t1.bin, hyg-t2.bin) and star-names.json are derived from:

HYG Database v4.1 — David Nash / astronexus

https://github.com/astronexus/HYG-Database

Licensed CC BY-SA 4.0

Share-alike applies to the database and to these derived binaries. If you redistribute them, keep this attribution and license the derivative under CC BY-SA 4.0.

Texture attribution

The Milky Way panorama

milkyway.jpg is not from the set below. It is:

The Milky Way panorama — ESO/S. Brunier

https://www.eso.org/public/images/eso0932a/ Licensed CC BY 4.0

The first image of ESO's GigaGalaxy Zoom project, taken for the International Year of Astronomy 2009. ESO's terms require the credit to be "clear and visible", so it is shown in the sky view's own panel whenever the layer is on, not only here. Downloaded 9 September 2026 as the 4000 x 2000 publication JPEG (publicationjpg), which is an exact 2:1 equirectangular and half the size of the 6000 x 3000 version.

It is in galactic coordinates, with the galactic plane running horizontally and the galactic centre at the middle of the frame — that is the projection GigaGalaxy Zoom chose. It has to be rotated onto the equatorial frame before it is drawn, or the band crosses the sky in the wrong place.

The full 800-megapixel original is not offered by ESO for copyright reasons and is not used.

Surface map attribution

There are two sources. The Sun, the planets and our own Moon are from Solar System Scope; the sixteen moon and Pluto maps below that are from USGS Astrogeology. The licences are different and so are the obligations.

The Sun, the planets and the Moon

These are from:

Solar System Scope — Solar System Textures

https://www.solarsystemscope.com/textures/ Licensed CC BY 4.0 (Attribution

4.0 International)

The licence permits use, adaptation and sharing for any purpose including commercially, and requires attribution. That credit is shown in the explorer's own panel on /solar, not only here — an obligation discharged somewhere nobody looks is not discharged.

Renamed to the body id on download so the loader can find them by id; the originals are otherwise unmodified.

The moons and Pluto

USGS Astrogeology Science Center — planetary map services

https://astrogeology.usgs.gov/ Public domain (a work of the United States

government), built from NASA mission imagery

No licence obligation attaches to these, but the credit is shown in the explorer's panel anyway, because USGS asks for it and because a reader deserves to know that a picture of Iapetus is a photograph and not a painting.

They are not downloaded as files. USGS runs an OGC web map service over the same mosaics, and this project asks it for a 2048 x 1024 render of each whole globe — a quarter of a megabyte each, rather than the hundreds of megabytes the source mosaics run to, with the resampling done at their end.

Fetched 10 September 2026.

Titan is the Venus problem again. To an eye Titan is a featureless orange ball; this map is Cassini's view through the haze, so it shows the surface rather than the planet. The same trade as Venus's radar map, and it is stated in the panel for the same reason.

Three of these have holes in them. About 32 per cent of Pluto, 34 of Charon and 39 of Triton has never been photographed — New Horizons and Voyager 2 each arrived with a hemisphere in polar night, and nothing has been back to any of them. Those regions are filled with #4A4F57, a flat colour picked not to resemble a surface, and the explorer names the body and the fraction. A bright fill would read as an ice cap and a dark one as a macula, and both bodies have both.

Uranus's five moons

USGS I-1920, Atlas of Uranian Satellites, 1:10,000,000 Topographic

Series (1988) — three printed sheets. Public domain.

These five are not from a map service, because there is no global mosaic of any of them to serve. Voyager 2 reached Uranus in January 1986 with the whole system tipped pole-on to the Sun, so only the southern hemispheres were lit. The northern hemisphere of Miranda, Ariel, Umbriel, Titania and Oberon has never been photographed by anything, and nothing has been back in the forty years since.

What USGS did publish is a controlled photomosaic of each southern hemisphere, printed in polar stereographic projection. Those sheets are downloaded, the photomosaic discs reprojected to equirectangular and the rest marked.

Fetched 10 September 2026.

Only the photomosaic is used. Each sheet also carries a "pictorial map" — an airbrushed rendering of the same hemisphere by a USGS illustrator. It is handsome and it is an interpretation, and this project does not draw surfaces.

The printed graticule is still there. Faint lines cross each disc on the original sheets and they survive the reprojection. They have not been painted out, because painting them out means inventing what is underneath. They are a scan artefact and they look like one.

Nothing was stretched. The greys are the scanned print's, converted to luminance and otherwise left alone, so the contrast is the lithograph's rather than a guess at the moons' real albedo.

Not everything in a USGS bucket is USGS's. Their basemap store also holds hand-painted maps of Uranus and Neptune by James Hastings-Trew, whose terms forbid redistributing the maps themselves. They are not used and must not be. Public domain is a fact about a file's provenance, not about where it is filed.

earth-night.jpg is the only one that is not a surface: it is the lights on Earth's night side, blended in through the terminator by a patch to the standard material rather than by a material of its own, so Earth is lit by exactly the same model as every other body and only gains a term.

What is deliberately not here

The "fictional" textures. The set also contains invented surfaces for Ceres, Eris, Haumea and Makemake. They are honestly labelled as fictional at the source, and this project shows what is actually known — so they are not used, and should not be.

Saturn's rings. The set includes 2k_saturn_ring_alpha.png, and it is not used. It is not served from the path the rest of the set comes from, and the rings turned out to be better built than borrowed: they are a radial profile and nothing else, so this project writes them out from the published band edges and optical depths instead. That costs no download and no obligation, and it can put the Encke gap at 133,410 km because that is where it is.

Proteus. Drawn as a flat colour, and there is nothing to fetch. Voyager 2 photographed it in 1989 from far enough away that it is a few dozen pixels across, and no map was ever made of it.

8k versions. They exist, and are around ten times the size — 50 MB or so in the repository for the ten Solar System Scope maps alone, against 18 MB for the whole directory as it stands. Worth revisiting only if the spheres are ever drawn large enough to want it; at 2k a body filling the screen is already at about the limit of the geometry.