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Centre of direct/retrograde motion



 
 
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  #1  
Old July 19th 18, 09:34 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Centre of direct/retrograde motion

https://www.theplanetstoday.com/

The Earth is about to overtake Mars at our relative closest distance so it will appear larger and brighter than at any other time in our mutual orbits around the Sun -

https://apod.nasa.gov/apod/ap160915.html

When the inner planets overtake us at the centre of retrogrades they appear darkest and lovingly understood during transits -

https://www.youtube.com/watch?v=_7U5VbasKr4&t=23s

The perspectives of direct/retrograde motions of the planets split between the faster and slower moving planets so this observation is now relative as we can see the Earth from the surface of Mars as a faster moving planet which will too show a dark phase at planetary transit.

No harm teaching the necessary partitioning at star parties as this is an enjoyable and decent thing to do.
  #2  
Old July 20th 18, 07:09 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Centre of direct/retrograde motion

There is no doubt that a direct/retrograde loop is illusory for a slower moving planet seen from Earth and an actual closed loop for a faster moving planet such as Venus -

https://apod.nasa.gov/apod/ap100613.html

http://www.insideastronomy.com/uploa...0_7_128459.jpg

Considering that direct/retrogrades observations haven't been touched as a topic since Copernicus first proposed the solution for a Sun centred system using the slower moving planets and a faster Earth overtaking them, the faster moving planets introduce a fresh injection of perspectives to the original scheme introduced 500 years ago.


These things are fairly easy once the observer is willing to give credit to those people who take the time to produce the sequential imaging and so what if the faster moving planets need a separate treatment with entirely different principles for resolving actual direct/retrograde motions, in a space age this is supposed to be common sense.












 




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