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APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 4:06 am
by APOD Robot
In the Shadow of Saturn
Explanation: In the shadow of Saturn, unexpected wonders appear. The
robotic Cassini spacecraft now orbiting
Saturn drifted in giant planet's
shadow for about 12 hours in 2006 and looked back toward the
eclipsed Sun. Cassini saw a
view unlike any other. First, the
night side of Saturn is seen to be partly lit by light reflected from its own
majestic ring system. Next, the rings themselves appear dark when
silhouetted against Saturn, but quite bright when viewed away from Saturn,
slightly scattering sunlight, in this
exaggerated color image. Saturn's rings light up so much that
new rings were discovered, although they are hard to see in the image. Seen in spectacular detail, however, is Saturn's
E ring, the ring created by the newly discovered
ice-fountains of the moon
Enceladus and the outermost ring visible above. Far in the
distance, at the left, just above the bright main rings, is the almost ignorable
pale blue dot of Earth.
[/b]
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 5:12 am
by revloren
This might just be APOD of the Year. Wow! And a dot of Earth to boot.
What a universe this is!
![Wink :wink:](./images/smilies/icon_wink.gif)
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 9:36 am
by stephinity
Fantastic APOD! I have a question though: I dont quite understand what's going on with the light of the rings in Saturn's shadow. If the backside of Saturn is being partially lit up by light reflected off the rings, why are the inner rings curved up so much, whereas the others seem aligned (with their rings light up directly by the Sun)? Any thoughts? Thanks!
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 9:49 am
by starstruck
This is a wondrous image.
To Stephinity . . good point, your comment made me look again at the picture. It looks to me like it may be some sort of a band in Saturn's atmosphere; it seems to be following the curvature of the planet rather than the rings. No idea why it shows up like this though.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 10:00 am
by RedFishBlueFish
Perspective.
Perspective: That one thing which I think most lacking, most needed, in my country today.
Remarkable image which leads to remarkable thoughts.
“Religions are many and diverse, but reason and goodness are one.”
Elbert Hubbard (1856-1915), Philosopher
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 11:16 am
by neufer
stephinity wrote:
Fantastic APOD! I have a question though: I dont quite understand what's going on with the light of the rings in Saturn's shadow. If the backside of Saturn is being partially lit up by light reflected off the rings, why are the inner rings curved up so much, whereas the others seem aligned (with their rings light up directly by the Sun)? Any thoughts? Thanks!
The
thin black band on Saturn is the night side equator...which is virtually unlit by the thin rings.
North of the dark equator, Saturn is lit up by the bright ring structure that you see in the APOD.
South of the dark equator, Saturn is lit up by the
much much brighter sunlit side of the rings;
this is what you are erroneously calling the "curved inner rings."
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 11:45 am
by Mary Gerdt
I am completely amazed. Thank you.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 11:57 am
by saturn2
Saturn, Saturn, my predilect planet.
This image is beautiful, indeed.
Some moons of Saturn have ice of water.
It will can to be important in explorations in the future.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 12:56 pm
by orin stepanek
And that pale blue dot! Wow; Ann would love that.
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 3:08 pm
by moonstruck
Wow! Simply amazing. Thanks, Cassini team.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 7:24 pm
by NoelC
This image alone was worth the cost of the mission.
-Noel
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 7:35 pm
by Torillion
Thanks, neufer, for the explanation, but I'm afraid I still don't get it. Perhaps it's because I don't know what a night side equator is and can't find a good explanation. Any chance you could explain it? I agree with revloren, this could be the APOD of the Year.
- t
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Sun Sep 04, 2011 8:47 pm
by neufer
Torillion wrote:
Thanks, neufer, for the explanation, but I'm afraid I still don't get it. Perhaps it's because I don't know what a night side equator is and can't find a good explanation. Any chance you could explain it?
You are confusing :
- 1) the full set of back-lit rings on the left & right with
2) the lit up backside of Saturn
as obscured by just the A & B rings.
While the two seem to have superficially similar structures they are actually quite distinct and they are clearly separated in the APOD near the outer edge of Saturn itself (as if someone had drawn a half circle in black marker around the bottom of Saturn).
On Saturn's surface
all you can really see is two simple ring bands:
- 1) a dark obscuration due to the B ring and
2) a fainter obscuration due to the A ring.
Ignore those two obscuring bands and what you see on Saturn is
- 1) a bright Southern Hemisphere
(due to backlighting from the rings)
2) a fainter Northern Hemisphere
(due to scattering from the rings) and
3) a thin dark equatorial line
(that receives no light at all from the thin rings).
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 1:00 am
by tECH hIPPY
Way Beautiful. Most totally excellent image. Do you suppose Earth is a crescent or full? Is Mars up there, too? Maybe way up in the upper left corner?
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 1:48 am
by Ann
This image testifies to the magic of reflection nebulae.
Of course this image is supremely valuable as well as beautiful, since it represents a prespective that we can never have from the Earth.
Speaking about the Earth, exactly where in the image is the pale blue dot located? I followed the link and saw a closeup of the pale blue dot, but where in the larger image can I find its position?
Ann
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 2:03 am
by bystander
PIA08324: Pale Blue Orb
"The Earth-and-moon system is visible as a bright blue point on the right side of the image above center. Here, Cassini is looking down on the Atlantic Ocean and the western coast of north Africa. The phase angle of Earth, seen from Cassini is about 30 degrees."
Credit: NASA/JPL/SSI
PIA08329: In Saturn's Shadow
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 2:31 am
by Ann
bystander wrote:
PIA08324: Pale Blue Orb
"The Earth-and-moon system is visible as a bright blue point on the right side of the image above center. Here, Cassini is looking down on the Atlantic Ocean and the western coast of north Africa. The phase angle of Earth, seen from Cassini is about 30 degrees."
Credit: NASA/JPL/SSI
PIA08329: In Saturn's Shadow
The image you showed in your post is not the right side of the image above center. And the inset can't be from that image, since the inset is clearly in black and white.
By the way, I did notice that today's APOD was produced from ultraviolet, infrared and "clear" filters, which means two invisible filters and one that won't show color. There can be little doubt, however, that the Earth looks blue from space, and if possible it should be shown as such, I think.
Ann
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 3:10 am
by bystander
Do you ever follow links? The link from APOD takes you to
PIA08329, which in turn takes you to
PIA08324, which is from the left side of the APOD.
Not since NASA's Voyager 1 spacecraft saw our home as a pale blue dot from beyond the orbit of Neptune has Earth been imaged in color from the outer solar system. Now, Cassini casts powerful eyes on our home planet, and captures Earth, a pale blue orb -- and a faint suggestion of our moon -- among the glories of the Saturn system.
Earth is captured here in a natural color portrait made possible by the passing of Saturn directly in front of the sun from Cassini's point of view. At the distance of Saturn's orbit, Earth is too narrowly separated from the sun for the spacecraft to safely point its cameras and other instruments toward its birthplace without protection from the sun's glare.
The Earth-and-moon system is visible as a bright blue point on the right side of the image above center. Here, Cassini is looking down on the Atlantic Ocean and the western coast of north Africa. The phase angle of Earth, seen from Cassini is about 30 degrees.
A magnified view of the image (
inset) taken through the clear filter (monochrome) shows the moon as a dim protrusion to the upper left of Earth. Seen from the outer solar system through Cassini's cameras, the entire expanse of direct human experience, so far, is nothing more than a few pixels across.
But then, you probably know better.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 3:23 am
by neufer
Ann wrote:
The image you showed in your post is not the right side of the image above center. And the inset can't be from that image, since the inset is clearly in black and white.
By the way, I did notice that today's APOD was produced from ultraviolet, infrared and "clear" filters, which means two invisible filters and one that won't show color. There can be little doubt, however, that the Earth looks blue from space, and if possible it should be shown as such, I think.
The
inset is from the right side (above center) of the image bystander shows.
In both the insert & the image the Earth is clearly
pale blue (not black & white).
The Earth is a deeper color of blue in the
enhanced color APOD image.
Cassini is looking down on the Atlantic Ocean and the western coast of north Africa;
if it had been looking down on the Pacific Ocean no doubt the Earth would have appeared bluer.
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 5:21 am
by Ann
Thanks.
Ann
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Mon Sep 05, 2011 9:19 pm
by stephinity
neufer wrote:
Torillion wrote:
Thanks, neufer, for the explanation, but I'm afraid I still don't get it. Perhaps it's because I don't know what a night side equator is and can't find a good explanation. Any chance you could explain it?
You are confusing :
- 1) the full set of back-lit rings on the left & right with
2) the lit up backside of Saturn
as obscured by just the A & B rings.
While the two seem to have superficially similar structures they are actually quite distinct and they are clearly separated in the APOD near the outer edge of Saturn itself (as if someone had drawn a half circle in black marker around the bottom of Saturn).
On Saturn's surface
all you can really see is two simple ring bands:
- 1) a dark obscuration due to the B ring and
2) a fainter obscuration due to the A ring.
Ignore those two obscuring bands and what you see on Saturn is
- 1) a bright Southern Hemisphere
(due to backlighting from the rings)
2) a fainter Northern Hemisphere
(due to scattering from the rings) and
3) a thin dark equatorial line
(that receives no light at all from the thin rings).
Thanks neufer for the detailed explanation... it clicked in my mind and now I totally see what you mean!
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Tue Sep 06, 2011 7:18 am
by Aiea
This is a reprint from October 16th 2006.
http://apod.nasa.gov/apod/ap061016.html
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Wed Sep 07, 2011 2:44 am
by hess
Simply Awsome!! It just happened that way? Thank you!
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Wed Sep 07, 2011 10:33 pm
by flyir
how great thou art
Re: APOD: In the Shadow of Saturn (2011 Sep 04)
Posted: Thu Sep 08, 2011 10:57 am
by Indigo_Sunrise