APOD: Crescent Saturn (2019 Jul 07)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Crescent Saturn (2019 Jul 07)

Post by APOD Robot » Sun Jul 07, 2019 4:11 am

Image Crescent Saturn

Explanation: Saturn never shows a crescent phase -- from Earth. But when viewed from beyond, the majestic giant planet can show an unfamiliar diminutive sliver. This image of crescent Saturn in natural color was taken by the robotic Cassini spacecraft in 2007. The featured image captures Saturn's majestic rings from the side of the ring plane opposite the Sun -- the unilluminated side -- another vista not visible from Earth. Pictured are many of Saturn's photogenic wonders, including the subtle colors of cloud bands, the complex shadows of the rings on the planet, and the shadow of the planet on the rings. A careful eye will find the moons Mimas (2 o'clock) and Janus (4 o'clock), but the real challenge is to find Pandora (8 o'clock). Saturn is now nearly opposite from the Sun in the Earth's sky and so can be seen in the evening starting just after sunset for the rest of the night.

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ecdowney
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by ecdowney » Sun Jul 07, 2019 5:38 am

Ok, I give up. Where is Pandora?

DL MARTIN

Re: APOD: Crescent Saturn (2019 Jul 07)

Post by DL MARTIN » Sun Jul 07, 2019 6:41 am

As well.

mfavret
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by mfavret » Sun Jul 07, 2019 7:22 am

Hi !
I'm french and I hope you will excuse my poor English.
It's better in full size :
Image
Last edited by mfavret on Sun Jul 07, 2019 10:58 am, edited 3 times in total.

atrin

Re: APOD: Crescent Saturn (2019 Jul 07)

Post by atrin » Sun Jul 07, 2019 10:26 am

There is also something at 9 o'clock (inside outer ring) and at 7 o'clock (just outside outer ring like Pandora)

mfavret
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by mfavret » Sun Jul 07, 2019 11:00 am

Position in the picture :
Image

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orin stepanek
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by orin stepanek » Sun Jul 07, 2019 11:37 am

What a wonderful probe Cassini was! It did a marvelous job exploring Saturn and it's moons and rings! :D 8-) :clap:
Orin

Smile today; tomorrow's another day!

PharAstro
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by PharAstro » Sun Jul 07, 2019 1:59 pm

Pardon me if these are stupid questions. 1) The shadow on the rings seems too skinny and inconsistent with the very long, conical shadow (almost cylindrical, I guess) that would have it's base at the day/night terminator. Can someone explain? 2) From the shadow of the rings on the planet, it would appear that the sun is "below" the rings (opposite hemisphere from the camera). But there is a region of dim glow that appears to be above the rings and on the night side. Is it "ring shine", analogous to earth shine during the new moon? Thanks.

sunson

Re: APOD: Crescent Saturn (2019 Jul 07)

Post by sunson » Sun Jul 07, 2019 3:08 pm

Questions:
1- How come there are two outermost rings on the left side but they become one towards the right?
2- How come the upper shadow line on the rings bulges upward?
3- Why the outer most ring(s) vary in whiteness (reflection)?

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neufer
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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by neufer » Sun Jul 07, 2019 4:19 pm

sunson wrote:
Sun Jul 07, 2019 3:08 pm

1- How come there are two outermost rings on the left side but they become one towards the right?
https://en.wikipedia.org/wiki/Rings_of_Saturn#F_Ring wrote:
<<The F Ring is the outermost discrete ring of Saturn and perhaps the most active ring in the Solar System, with features changing on a timescale of hours. It is located 3,000 km beyond the outer edge of the A ring. The ring was discovered in 1979 by the Pioneer 11 imaging team. It is very thin, just a few hundred km in radial extent. While the traditional view has been that it is held together by two shepherd moons, Prometheus and Pandora, which orbit inside and outside it, recent studies indicate that only Prometheus contributes to the confinement. Numerical simulations suggest the ring was formed when Prometheus and Pandora collided with each other and were partially disrupted.

More recent closeup images from the Cassini probe show that the F Ring consists of one core ring and a spiral strand around it. They also show that when Prometheus encounters the ring at its apoapsis, its gravitational attraction creates kinks and knots in the F Ring as the moon 'steals' material from it, leaving a dark channel in the inner part of the ring. Since Prometheus orbits Saturn more rapidly than the material in the F ring, each new channel is carved about 3.2 degrees in front of the previous one.>>
Art Neuendorffer

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Re: APOD: Crescent Saturn (2019 Jul 07)

Post by Boomer12k » Sun Jul 07, 2019 9:32 pm

Always good to see Saturn...

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