Methodology
Astrodle’s draw is a pure function of your anonymous id and the UTC date, so a refresh or a retry always returns the same result. The draw resets at 00:00 UTC. Nothing about the draw is random at request time and no external astronomy service is called — everything runs against a catalog frozen at release.
Two-stage draw
First a family is chosen by a published probability. Then an object is drawn from your personal non-repeating deck for that family — you will not see the same object twice until you have seen every object in that family.
| Family | Odds | Catalog size |
|---|---|---|
| Compact object (black_hole) | 2% | 13 |
| Compact object (neutron_star) | 6% | 3,125 |
| Stellar signal (star) | 30% | 112,980 |
| Planetary signal (exoplanet) | 18% | 6,335 |
| Deep-sky signal (nebula) | 9% | 399 |
| Deep-sky signal (cluster) | 8% | 877 |
| Deep-sky signal (galaxy) | 16% | 63,349 |
| Local object (solar_system) | 11% | 26,882 |
A uniform draw over the whole catalog would return a faint star or a faint galaxy almost every day. The family odds are hand-designed so the game stays varied, and they are versioned: your result is stamped with the catalog and rules version that produced it.
Two-layer rarity
- Family tier — the coloured headline, tracking the family odds.
- Badges — each badge’s score is
round(100 / frequency), where the frequency is measured by simulating 50,000,000 draws over the current catalog. Regenerated whenever the draw model changes. Badges cover both measured traits of the object and well-established facts about its class.
Discovery Points are the sum of a result’s badge scores. They are not the rarity headline — the family tier is — but for players with an account they are the ranking metric on the daily, weekly and all-time leaderboards. The object’s identity itself awards no points, so a small specialist catalog can’t inflate every result. The “Top X% for a nebula” line compares your points only against other objects in the same family, where the draw is uniform, so that comparison is honest; a global percentile would mostly track which family you drew, so it is not offered.
Catalog v0 · rules v0 · 213,960 eligible objects · 223 released badges.