Reference

Sources

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Doors

Stars keeps the choir plate Jupiter · Io. This house doors it; it does not replace it.

The Book keeps the memoir of the degree, the survey, and the unrounded hours. This house excerpts and doors. It does not overwrite.

This house owns the encounter with the system: scale, four weathers, resonance as an instrument, Galileo's week, Rømer's late clock, and the particular myths.

Walk

Four worlds

Io
Fire under law · 1.769137786 d
Europa
Ice over a hidden sea · 3.551 d
Ganymede
A world with its own field · 7.155 d
Callisto
The old cratered quiet · 16.689 d

Atlas

Heliocentric distance: ~5.2 AU; A year of about 11.86 Earth years, the long clock called a Jupiter return.
Mean density: 1.33 g/cm³; Less dense than water-rock worlds. A giant of light elements.
Equatorial gravity: ~24.8 m/s²; About 2.5 times Earth’s surface gravity, if there were a surface.
Bond albedo: ~0.50; Clouds return about half the sunlight. Cream and ochre are weather, not rock.
Axial tilt: 3.13°; Almost no seasons of the Earth kind. The weather is internal.
Rings: Faint, dusty; Discovered by Voyager 1 in 1979. Not Saturn’s architecture. A thin halo of spent material.
Named moons: 115 (NASA, Aug 2026); The four Galilean worlds hold ~99.997% of the mass in orbit. The rest is a swarm of captives. Census numbers move; the four do not.
Great Red Spot: Larger than Earth; An anticyclone tracked since the 19th century, possibly since Hooke/Cassini in the 1660s. It has been shrinking. It is still a world of storm.

Ledger

mission
NASA Science · Jupiter
Agency overview of the planet, moons (115 named as of August 2026), and missions.
catalogue
NASA Science · Jupiter's moons
Galilean satellites; census dated August 2026.
catalogue
JPL Horizons
Io sidereal period used in the Book: 1.769137786 d = 42.4593 h.
mission
Juno mission · NASA / SwRI / JPL / MSSS
Polar orbiter, 2016–present. JunoCam plates are processed science images. January 2021 extension: 42 additional orbits, expanding from the planet into the Jovian system (Ganymede, Europa, Io, rings).
mission
NASA · Juno mission expands into the future (13 January 2021)
Primary source for the 42 additional orbits of the extended mission, including planned flybys of Ganymede, Europa and Io. A schedule. Not a slogan.
catalogue
NASA Science · Io
Io’s orbit is about 42.5 hours. Rapid orbit and forced eccentricity drive the tidal heating of the most volcanic world known. The Book does not round the Horizons sidereal period: 1.769137786 d = 42.4593 h. Rømer’s own phrase was about 42.5 hours.
mission
Hubble Site · Jupiter
Hubble limb, family portrait, and ultraviolet aurora plates used in this house. NASA / ESA. Processed or spectral as labelled.
mission
ESA JUICE
Jupiter Icy Moons Explorer. Bound for Ganymede, with Europa and Callisto in the tour.
mission
NASA Europa Clipper
Multiple flybys of Europa. An ocean inferred is not an ocean sampled.
mission
Galileo orbiter archive
1995–2003. Moon mosaics in this house are Galileo / Voyager plates.
historical
Galileo Galilei, Sidereus Nuncius (Venice, 1610)
First published account of the four attendants. Observations from Padua begin 7 January 1610; recognition by 15 January. Sketches of points in a line, not a photograph.
historical
Simon Marius, Mundus Iovialis (Nuremberg, 1614)
Names Io, Europa, Ganymede, Callisto, credited to a suggestion of Kepler. Discovery and naming are different events.
historical
Ole Rømer, communication to the Académie Royale des Sciences, 1676
Io eclipses as a clock; light delayed by extra distance. His own phrasing: about 42.5 hours for a revolution of the first satellite. English door: Philosophical Transactions, 1677. The 22-minute crossing is a travel time, not a modern kilometres-per-second figure.
historical
Pierre-Simon Laplace on the three-body lock of Io, Europa and Ganymede
Paris, late eighteenth century. Mean-motion lock 4:2:1. Laplace explained the lock; he did not know Io was volcanic.
paper
Peale, Cassen & Reynolds, Melting of Io by Tidal Dissipation (Science, 1979)
Predicted tidal melting from the forced eccentricity. Voyager 1 photographed Io’s plumes days later.
historical
Giovanni Domenico Cassini · Jupiter’s belts and a southern spot (1660s–1670s)
Bologna, then Paris Observatory. Belts resolved; rotation timed from a southern spot. Continuity with today’s Great Red Spot is contested.
historical
Enūma Anu Enlil · celestial omen series
About seventy tablets of celestial and terrestrial omens, compiled and copied in the second and first millennia BCE. Used by Neo-Assyrian court scholars. Not personality astrology: if a light behaves thus, then king and land. Jupiter material edited in Reiner and Pingree, Babylonian Planetary Omens, Part Four (2005).
historical
Astronomical Diaries from Babylon · Sachs and Hunger
Akkadian clay records, about 652 to 61 BCE. Most surviving tablets: British Museum. MUL.BABBAR (white star) is the Diaries’ name for the wanderer. Observation, weather, prices, and city events on one tablet. Edition: Astronomical Diaries and Related Texts from Babylonia (Vienna).
historical
Reiner and Pingree, Babylonian Planetary Omens, Part Four (2005)
Critical edition of first-millennium Jupiter omens (MUL.SAG.ME.GAR, Šulpae, related designations). Distinguishes omen protasis from later astronomical inference.
historical
Sima Qian, Shiji · Treatise on the Celestial Offices
Han court history. Celestial offices as state knowledge. Suìxīng (Year Star) and the five moving stars, including 木星 the Wood Star. A year-count from a twelve-year circuit, not a king-planet doctrine.
historical
Rigveda · Bṛhaspati; later Jyotisha / Navagraha
Vedic office: priest and counselor. Planetary identification with the wanderer is later. Thursday (Guru-vāra, Bṛhaspati-vāra) keeps the name. Do not read the hymn as a field guide.
archive
Stars · Jupiter · Io
Canonical choir plate in Stars. This house doors it.
archive
The Book of 42 · Stars · Jupiter
Memoir of 4°20′, 28 June 2025, 1693 station, Io 42.46 h, Laplace 4:2:1. Canonical wording excerpted here, not rewritten.
image
PIA22946 · JunoCam
Processed Juno image of Jupiter's atmosphere. NASA / JPL-Caltech / SwRI / MSSS.
image
PIA21972 · Great Red Spot, Juno PJ7
Close pass 11 July 2017. Processed. NASA / JPL-Caltech / SwRI / MSSS.
image
Hubble · Jupiter and the Great Red Spot
NASA / ESA. Processed color. Used as limb plate.
image
Hubble · Jovian aurorae
Ultraviolet aurora. False-colour / processed science image, not what the unaided eye would see.
image
PIA24791 · Ganymede, Juno
7 June 2021 close pass. Processed. NASA / JPL-Caltech / SwRI / MSSS.
image
PIA00271 · Europa, Galileo true-color
True-color globe. NASA / JPL.
image
Hubble · Jupiter and the Galilean moons
Family portrait used as notation: four worlds held in one frame. NASA / ESA.
image
Names of the wanderer
Generated interpretation for this house. Five public names set as type on a plate. Not facsimiles of inscriptions, not portraits of gods.
image
Iuppiter Optimus Maximus · generated stone
Generated interpretation of a Capitoline dedication. Not a facsimile of a known inscription.
image
ΖΕΥΣ · generated star field
Generated interpretation. A wanderer, not a portrait of a god.
image
MUL.BABBAR · generated tablet
Generated interpretation of an Astronomical Diary. Cuneiform as texture, not a readable witness.
image
木星 · generated ink
Generated interpretation of the Wood Star as type. Not a historical treatise page.
image
Bṛhaspati · generated palm-leaf
Generated interpretation of a palm-leaf fragment. Not a surviving manuscript.