Greetings to alll “Retrograde Lovers” around the world !
Here’s a fun ‘summer quiz’ (or ‘winter quiz’ for our esteemed “down-under” members) that I’m submitting for your entertainment and thoughtful appraisal. I hope you’ll appreciate my ‘quiz format’ for discussing cosmic matters and that you’ll happily participate in solving the riddle…
So here are the facts: in 2012, both Mars and Eros (coincidentally) passed quite close to the Earth - and both were observed to briefly reverse direction (i.e. moving “retrograde”). Eros was exceptionally close to Earth (only about 0.2AU) while Mars was more than 3 times as distant (about 0.7AU). Now, before we get on - and in order to understand how this is ‘officially explained’ - you must do the effort to check out this NASA/JPL webpage which features a simulator of the supposed orbit of Eros, our most ‘famous’ asteroid. Here’s a screenshot I made of that NASA/JPL webpage:
In the top right corner of the NASA simulator you’ll find a ‘clock box’. Click on it - and insert the date 2012-03-01. This will get you to the situation shown in my above screenshot. You may then play around back and forth with the simulator to see just how both Eros and Mars were officially meant to pass close to Earth between January and April 2012.
You may now ask: “what was ACTUALLY OBSERVED of these retrograde motions? Have they been documented photographically?” The answer to this rightful question is : yes indeed.
At top left of my below image (a screenshot from the TYCHOSIUM simulator that you can all verify for yourselves) there’s a digital rendition of a timelapse photo-composite captured by the famed Turkish astrophotographer Tunc Tezel, documenting the observed 2012 Mars passage:
So now you may ask: “What about the EROS passage and retrograde motion? Has it also been documented?”
Well, the below image is from the Wikipedia entry for “asteroid Eros” which also features this curious sentence (my bolds):
"Under this condition, the asteroid actually appears to stop, but unlike the normal condition for a body in heliocentric conjunction with Earth, its retrograde motion is very small".
“Very small”? How so?
So here’s the core question of this intellectual “summer quiz” of mine:
How would you explain to a child the reason why Eros is observed to retrograde FAR LESS than Mars?
I know, it’s a pretty tough question - but you are allowed to ask assistance from your grandmothers who are usually very good at solving crosswords / sudokus and such like.