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Equinox image 2018



 
 
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  #1  
Old March 9th 18, 05:18 PM posted to sci.astro.amateur
Gerald Kelleher
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Default Equinox image 2018

https://epic.gsfc.nasa.gov/

For whatever reason known only to themselves, NASA has decided not to represent the images of the Earth with a constant 23 1/2 degree inclination so anyone placing their cursor at the South pole latitude will see it is not an accurate representation of the Earth relative to the Sun or the circle of illumination.

I guess they really need their pivoting circle of illumination by manipulating imaging as they did this time last year -

https://apod.nasa.gov/apod/ap170319.html

People must have no sense of pride in themselves so whining in my direction is not going to change things for the better.



  #2  
Old March 10th 18, 07:51 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Equinox image 2018

The only accurate representation of the Earth in the bank of EPIC images is on the Solstice -

https://epic.gsfc.nasa.gov/?date=2017-12-21


Right now so close to the Equinox, the image should show the recognizable 23 1/2 degree inclination where the polar latitudes exist close to the circle of illumination instead of showing a planet with a zero degree inclination. It make a change from the pivoting circle of illumination but truthfully it is not much better.

I do not know what drives people to do this unless they get a satisfaction from avoiding the genuine observation that the North and South poles will turn across the fully illuminated face of the Earth and parallel to the orbital plane just as Copernicus originally described it in his Commentariolus (1513) -

" The third is the motion in declination. For, the axis of the daily rotation is not parallel to the Grand Orb's axis, but is inclined [to it at an angle that intercepts] a portion of a circumference, in our time about 23 1/2°. Therefore, while the earth's center always remains in the plane of the ecliptic, that is, in the circumference of a circle of the Grand Orb, the earth's poles rotate, both of them describing small circles about centers [lying on a line that moves] parallel to the Grand Orb's axis" Copernicus

He sacrificed this view in De Revolutionibus in order to account for the precession of the equinoxes but that is a technical issue that requires reasonable people who have enough self-discipline to discuss the issue without lunging at it.









 




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