Where the facts come from
Every factual claim on this site links to its source. This is the full list.
How we checked
Each fact was written alongside its source. Our build script stores the source text and, for every fact, checks that the key words and figures really appear in it. 103 of 103 checks passed when this site was last built (27 Oct 2026). Where we couldn’t find a NASA, JPL or ESA page that said it, we left the claim out.
Our own sums
The storm explorer, You on Jupiter and Moon Transit Catcher use figures from NASA pages, but the results (kilometres from miles, “Earths across”, Jupiter ages and weights, the game’s speeds) are worked out by us, in your browser. They are labelled as our sums.
Things that change
Moon counts go up, missions launch and end, and the Great Red Spot keeps changing shape. Facts like these are marked “checked 27 Oct 2026” so you know how fresh they are. Fixed facts, such as Pioneer 10’s flyby in 1973, don’t change. Where NASA pages disagree, we show both and say so.
All sources (23)
- ESA: Juice factsheet (2 facts)
- NASA JPL: Juno (1 fact)
- NASA Science: Callisto facts (3 facts)
- NASA Science: Comet Shoemaker-Levy 9 (2 facts)
- NASA Science: Europa (3 facts)
- NASA Science: Europa Clipper (2 facts)
- NASA Science: Galileo (3 facts)
- NASA Science: Ganymede facts (7 facts)
- NASA Science: Hubble watches the Great Red Spot behave like a stress ball (2024) (2 facts)
- NASA Science: Io facts (8 facts)
- NASA Science: Juno (1 fact)
- NASA Science: Juno redefines the size and shape of Jupiter (2026) (1 fact)
- NASA Science: Juno stories (1 fact)
- NASA Science: Jupiter (5 facts)
- NASA Science: Jupiter exploration (3 facts)
- NASA Science: Jupiter facts (32 facts)
- NASA Science: Jupiter moons (3 facts)
- NASA Science: Jupiter’s Great Red Spot is shrinking (2014) (6 facts)
- NASA Science: Pioneer 10 (1 fact)
- NASA Science: Voyager 1 (1 fact)
- NASA Space Place: All about Jupiter (2 facts)
- NASA Space Science Data Coordinated Archive (NSSDCA): Jovian satellite fact sheet; used for the moon orbit periods in Moon Transit Catcher (3 facts)
- NASA Space Science Data Coordinated Archive (NSSDCA): Jupiter fact sheet; used for the weight and age calculator (11 facts)