Why the shadow of Saturn's F ring across the cratered ice-moon seems, in my opinion, not to be in accordance with what seems to be the sunlight procedence in the picture?
Thank you
2006 April,5: Strange Shadow?
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quantumtahki
- Asternaut
- Posts: 1
- Joined: Wed Apr 05, 2006 4:39 pm
- Location: Pennslyvania
F ring loves me
I also must express confusion on April 5th's picture.
But take this into consideration. ...
The far side of the rings may be shadowed by that big plumpy Saturn itself. Also, this view, not an edge on. Cassini is angled bellow the plane of the rings, we are practically looking threw F Ring, pointing at Rhea
So that mysterious "picturesque vista" of F ring "on" Rhea isnt as mysterious after all.
~alice~
But take this into consideration. ...
The far side of the rings may be shadowed by that big plumpy Saturn itself. Also, this view, not an edge on. Cassini is angled bellow the plane of the rings, we are practically looking threw F Ring, pointing at Rhea
So that mysterious "picturesque vista" of F ring "on" Rhea isnt as mysterious after all.
~alice~
In The Light
Moontrail,
It's a trick of the light, thru orientation.
As our eyes are not genetically programed to see objects in space and the topsy-turvy lighting they so often have; because there is no "up and down".
Our genetic programing is orientated to having a gravitational field present for reference of up and down. In space that is not the case.
I used to have a lot of problems with the early moon photos, as the craters looked like upsidedown saucers; the dips looked like bumps and vice versa. The shadow problem of correct orientation. Even turning the photo over didn't solve the 'correct resolution problem' most of the time, once in a while it did.
Here, the terminator on the moon is the key. It shows the sunlight is coming from the oblique right side of the photo. This means that the part of Saturn's ring that is casting the shadow on the moon is NOT the part of the ring that is in the photo; but our eye wants to see it as thus. The far away part of the ring; on the other side of Saturn, is casting the shadow on the moon.
The part of the ring in the photo is illuminated from below, it looks like the ring is above the moon; which it is on THIS side of Saturn. The ring is reversed on the OTHER side of Saturn, to be lower, and so that lowers it just enough to slice across the top of the moon, which is on the other side of Saturn; as well as the part of the ring which is casting the shadow across the very top of the moon.
Hope this helps unscramble your eye's programing in the brain which we all have.
I was once trying to read words on the tv screen while lying down, and I could not resolve the letters into words fast enough to read it, it was unintelligible; because I was not perpendicular to the writing I could not resolve it into words. A trick of orientation problem, just like light and shadow in a space environment.
It's a trick of the light, thru orientation.
As our eyes are not genetically programed to see objects in space and the topsy-turvy lighting they so often have; because there is no "up and down".
Our genetic programing is orientated to having a gravitational field present for reference of up and down. In space that is not the case.
I used to have a lot of problems with the early moon photos, as the craters looked like upsidedown saucers; the dips looked like bumps and vice versa. The shadow problem of correct orientation. Even turning the photo over didn't solve the 'correct resolution problem' most of the time, once in a while it did.
Here, the terminator on the moon is the key. It shows the sunlight is coming from the oblique right side of the photo. This means that the part of Saturn's ring that is casting the shadow on the moon is NOT the part of the ring that is in the photo; but our eye wants to see it as thus. The far away part of the ring; on the other side of Saturn, is casting the shadow on the moon.
The part of the ring in the photo is illuminated from below, it looks like the ring is above the moon; which it is on THIS side of Saturn. The ring is reversed on the OTHER side of Saturn, to be lower, and so that lowers it just enough to slice across the top of the moon, which is on the other side of Saturn; as well as the part of the ring which is casting the shadow across the very top of the moon.
Hope this helps unscramble your eye's programing in the brain which we all have.
I was once trying to read words on the tv screen while lying down, and I could not resolve the letters into words fast enough to read it, it was unintelligible; because I was not perpendicular to the writing I could not resolve it into words. A trick of orientation problem, just like light and shadow in a space environment.
*link*
I also found this confusing. I considered the silhouette explanation, but I am still worried by the apparent size of Rhea - since it is in the background of this image (and hence the rings can be silhouetted against it), it must be at quite a distance from Cassini - so far in fact that I would expect the angular size to be far smaller...
does anyone know how close Rhea sits to the outer rings, and also its size relative to Earths moon?
I have trouble picturing this unless either
-Rhea is exceedingly large
-The image is taken very close to the edge of the rings, or
-The width of the image frame is very small, and hence the zoom is very large.
The relative sizes just don't seem right =S
I also found this confusing. I considered the silhouette explanation, but I am still worried by the apparent size of Rhea - since it is in the background of this image (and hence the rings can be silhouetted against it), it must be at quite a distance from Cassini - so far in fact that I would expect the angular size to be far smaller...
does anyone know how close Rhea sits to the outer rings, and also its size relative to Earths moon?
I have trouble picturing this unless either
-Rhea is exceedingly large
-The image is taken very close to the edge of the rings, or
-The width of the image frame is very small, and hence the zoom is very large.
The relative sizes just don't seem right =S
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orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
here is more info on Rhea.
http://www.solarviews.com/eng/rhea.htm
It should answer the question on it's size.
Orin
http://www.solarviews.com/eng/rhea.htm
It should answer the question on it's size.
Orin
www.johndobson.org
Mucho extensive info on Rhea ! , thanks Orin. 
I now am wondering where is Saturn's shadow? and why do the rings disappear so fast into darkness. and where to the right exactly is Saturn?
After about a year? of being unavailable, John Dobson's website is now back up.
http://www.johndobson.org/
the Articles by John selection
They are still a bit too condensed and in my opinion need more expanding to carry a better argument for the points he is making. Unless one is familiar with his logic, it goes too fast for someone new to his line of thinking. Which is disappointing, as most will not give it the necessary thought before dismissing his ideas as too radical, or not well thought out.
I now am wondering where is Saturn's shadow? and why do the rings disappear so fast into darkness. and where to the right exactly is Saturn?
After about a year? of being unavailable, John Dobson's website is now back up.
http://www.johndobson.org/
the Articles by John selection
They are still a bit too condensed and in my opinion need more expanding to carry a better argument for the points he is making. Unless one is familiar with his logic, it goes too fast for someone new to his line of thinking. Which is disappointing, as most will not give it the necessary thought before dismissing his ideas as too radical, or not well thought out.
Rhea in comparison
This link shows a size comparison between Saturn and its moons as well as an orbit distance chart.
http://pds-rings.seti.org/saturn/images/ring_sat.gif
Rhea is just under 1/4 the size (diameter) of our moon.
http://www.imagehosting.us/index.php?ac ... nt=1288344
Note: Moon & Rhea image inserted for scale comparison between the two and not between them and saturn.
[/img]
This link shows a size comparison between Saturn and its moons as well as an orbit distance chart.
http://pds-rings.seti.org/saturn/images/ring_sat.gif
Rhea is just under 1/4 the size (diameter) of our moon.
http://www.imagehosting.us/index.php?ac ... nt=1288344
Note: Moon & Rhea image inserted for scale comparison between the two and not between them and saturn.
[/img]