world · Solar system · a plate in Stars
Jupiter · Io
Jupiter V · Io
Io’s orbital period is about 42.46 hours. That is a forty-two the Book does not round.
Expansion under law. Thunder in the old stories. Resonance and radio in the new ones.
From the letters
“A 4:2:1 resonance that drives volcanoes.”
Astronomy · astrophysics
- Magnitude
- Jupiter ~ −2.2 (varies)
- Distance
- Jupiter ~ 5.2 AU from the Sun
- Spectrum
- volcanic moon of a gas giant
- Coordinates
- wanders · ecliptic
Laplace resonance 4:2:1 with Europa and Ganymede. Tides drive the volcanoes.
Io sidereal period ≈ 1.769 days ≈ 42.46 hours.
Orbital resonance Io:Europa:Ganymede = 4:2:1. The forced eccentricity powers Io’s volcanism.
Jupiter’s year is about 11.86 Earth years. Biggest world in the solar system. Distance from the Sun about 5.2 AU.
Historical story · observation
A moon, then a law
- January 1610Galileo recorded four attendants of Jupiter. Io is the innermost of those four.
- Laplace, laterThe 4:2:1 resonance among Io, Europa, and Ganymede became a dynamical law. The volcanoes follow from the tides the resonance will not let rest.
Living
Not only stars. The looking widened to a moon whose clock prints forty-two without help.
On 28 June 2025 Jupiter stood at 4°20′ Cancer, a degree the Book already knew from a rising coordinate.
Sources
- JPL Horizons
- Laplace resonance literature
- Swiss Ephemeris
Choir
Rotanev · SualocinSiriusIzar · PulcherrimaThubanCapellaRigelMeropeTolimanM42Jupiter · IoSpicaFomalhautArcturusAlhenaCanopusWorking choir · not a planetarium