Mass_Io=8.93e22
Mass_Europa=4.80e22
Mass_Ganymede=1.48e23
Mass_Callisto=1.08e23
http://www.nineplanets.org/data1.html
Mass_Europa+Mass_Ganymede=1.9600e+023
Mass_Io+Mass_Callisto = 1.9730e+023
(Mass_Io+Mass_Callisto)/(Mass_Europa+Mass_Ganymede) = 1.0066
"Io, Europa and Ganymede are locked together in a 1:2:4 orbital
resonance (Laplace resonance) and their orbits evolve together.
Callisto is almost part of this as well. In a few hundred million
years, Callisto will be locked in too, orbiting at exactly twice the
period of Ganymede (eight times the period of Io). "
http://www.nineplanets.org/jupiter.html
( Io + Callisto ) and ( Europa + Ganymede ) are locked together in
a 1:1 Mass resonance named after Aleksandr Timofeev
=========================================================
( Mass_Io + Mass_Callisto ) / ( Mass_Europa + Mass_Ganymede ) = 1.0066
=========================================================
Mass_Io - mass of Io
Mass_Callisto - mass of Callisto
Mass_Europa - mass of Europa
Mass_Ganymede - mass of Ganymede
> "In 1610 when Galileo first pointed a telescope at the sky he
> discovered
> Jupiter's four large moons
> Io, Europa, Ganymede and Callisto (now known as the Galilean moons)"
> "Io, Europa and Ganymede are locked together in a 1:2:4 orbital
> resonance (Laplace resonance) and their orbits evolve together.
> Callisto is almost part of this as well. In a few hundred million
> years, Callisto will be locked in too, orbiting at exactly twice the
> period of Ganymede (eight times the period of Io). "
> http://www.nineplanets.org/jupiter.html
>
> ( Io + Callisto ) and ( Europa + Ganymede ) are locked together in
> a 1:1 Mass resonance named after Aleksandr Timofeev
>
> =========================================================
> ( Mass_Io + Mass_Callisto ) / ( Mass_Europa + Mass_Ganymede ) = 1.0066
> =========================================================
>
> Mass_Io - mass of Io
> Mass_Callisto - mass of Callisto
> Mass_Europa - mass of Europa
> Mass_Ganymede - mass of Ganymede
Updated estimate
Mass_Io = 5959.916
Mass_Callisto = 7179.289
Mass_Europa = 3202.739
Mass_Ganymede = 9887.834
http://ssd.jpl.nasa.gov/sat_props.html
(The Ratio is published for the first time, the link to authorship
Aleksandr Timofeev is mandatory)
=========================================================
(Mass_Io + Mass_Callisto) / (Mass_Europa + Mass_Ganymede) = 1.0037
< 1.0066
=========================================================
This ratio 1:1 for mass couples of Galilei satellites of Jove is so
wonderful as well as Laplace ratios 1:2:4 for cycles times of the same
satellites.