OT: Io & Europa orbiting Jupiter ...

… above the Great Red Spot.



Galileo Galilei is credited with being the first person to observe the moons of Jupiter, with the help of his new telescope. It was in those observations that Galileo surmised that the moons were in orbit around the larger planet.

Recently, however, one of the famous documents attributed to Galileo was determined to be a forgery. This document contains, in part, a description and sketches of Jupiter’s moons.


Since 1938, one of the most prized items in the University of Michigan library’s collection has been a rare manuscript page allegedly written by Galileo. But after an internal investigation, the library’s curators have concluded that the manuscript is in fact a fake—and most likely executed by a well-known 20th-century forger. The curators were tipped off about the forgery by Georgia State historian Nick Wilding, who became suspicious of the manuscript’s authenticity while working on a biography of Galileo.

I have a documentary series on DVD on the history of science. I’m pretty sure the documentary, at one point, shows this forgery document as if it was real. The series is The Day the Universe Changed by James Burke. I will need to go back and re-watch that episode.

  • Pete

thnx! ludicrously amazing and wonderful short video

d fb

This page is down

The Captain

Retry worked!


The Captain

Anyone notice the deliberate error?

The moon closest to the planet is going slower than the moon nearest the viewer. Wrong way round.


Is it that or is that the relative motion of the Cassini spacecraft?


The moon closest to the planet is going slower than the moon nearest the viewer. Wrong way round.

As PucksFool surmised:

@jordanliles @CassiniSaturn The motion isn’t wholly accurate as I made it to look prettier than it was correct. But it’s meant to portray the motion visible from a spacecraft that’s moving at a velocity faster than the moons are orbiting. So, from a stationary perspective, Io would move faster than Europa.


1 Like

I believe I have just had my broken clock experience of the day. :upside_down_face: