[Physics] Physics Digest, Vol 7, Issue 5

[cj at mb-soft.com]

Please remember that I spent six months doing the math, based on VSOP87 data.  Ganymede and Callisto are generally much farther away from the other and much larger.  Yes, the math indicated a rare (solar) eclipse of one of the smalller ones by Ganymede, but that seemed to be extremely rare.  Io and Europa are often much closer together, and of roughly the same diameter, so most of the eclipses and occultations that I had calculated involved them, one way or the other.

I apologize to your group for bringing up an ancient incident which seems to have distracted from your gravitational interests.  I had only brought it up due to seeing some logical  weaknesses in some arguments you often discuss, and your recent interest in "one-way speed of light".  I merely thought that one or more of you would find interest in the "geometrcal issue I had dome math on.  The VSOP87 terms all exist, so that simple Calculus can determine the location of any major object in the Solar System, and I happened to have been intrigued at how rarely the Galilean moons seem to have ever seem in mutual eclipses or occultations.  Ditto, calculatingn the exact distance from such an event to where a particular city on Earth at any moment is now doable, where 50 years ago, it was not.

Such mutual eclipses of Io and Europa are not remotely like the four-hour Lunar eclipses here.  As I had mentioned, the entirety of the episode is rarely even sixteen seconds.  An astronomer observing such an event does not see a "fading" but all the historical records semm to describe a "blinking out" or similar comment.  I thought that "time accuracy" might be useful for your group now, regarding trying to obtain a "one-way speed of light".  You refer to "almost" disappeared.  You might look into the archives of the historical astronomy records.  Even when an annular eclipse had clearly occurred, the astronomer still referred to it as "blinking out" as the moon dropped in celestiasl magnitude by a lot (from Earth).  I am not aware of anyone ever mentioning being able to see an Annularly eclipsed event, they all seem to describe it as "yes" or "no".  I agree that I would love to see a video of an annular mutual eclipse of Io and Europa.

In case any of you are interested, also in 1992, I was fascinated by the rather strong mutual gravitation effects of Io and Europa when they do a nearby pass in orbit every few hours.  I did a lot of math on that as well, and was amazed that both of those moons distorted in shape by nearly a mile due to the pass.  They each already are severely egg-shaped due to Jupiter, and the two Vectors of the gravitational forces do terible things to the structure of both of them.  Even now, I have not seen NASA acknowledge this, and its internal frictional heating effects in both of them.  NASA seems to speculate on why Europa is so "geologically active" but I did that math (again due to Newton and his Force Vectors, and I was satisfied about the heat source inside Europa and Io.

Feel free to go back to your initial interests.

Carl Johnson  
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