Uranus System Imaging Options

[machi]

I finished my first good image of Uranus.
Planet is colorized from three filtered images (orange, green, blue).
Slightly brownish color of rings is entirely artificial.

Attached thumbnail(s)

 

[Antdoghalo]

Found this really cool 5K high resolution map of Miranda by Robin Charles Gilbert. While there are other maps of Miranda, I have yet to see any others that really showcase the full resolution of the Voyager images quite like this one.
http://www.robingilbert.com/blog/2017-08-2...las-of-miranda/

[TrappistPlanets]

Found this really cool 5K high resolution map of Miranda by Robin Charles Gilbert. While there are other maps of Miranda, I have yet to see any others that really showcase the full resolution of the Voyager images quite like this one.
http://www.robingilbert.com/blog/2017-08-2...las-of-miranda/

very nice, wander is there any hidden uranuan back shine on oberon and miranda no one exposed yet?

[JRehling]

When a Uranian pole is pointed more or less at the sun, then the potential uranusshine on a moon would be on the ~1/4 of the surface that can, at that time, see the planet but not the Sun. It's a considerably worse case than with Jupiter or Saturn.

That said, it was a challenge for Voyager to take images of the moons even in sunlight, since the cameras were spec'ed only for Jupiter and Saturn. The light of a half Uranus would be orders of magnitude less than sunlight, so it seems far out of the realm of possibility for those cameras.

[TrappistPlanets]

When a Uranian pole is pointed more or less at the sun, then the potential uranusshine on a moon would be on the ~1/4 of the surface that can, at that time, see the planet but not the Sun. It's a considerably worse case than with Jupiter or Saturn.

That said, it was a challenge for Voyager to take images of the moons even in sunlight, since the cameras were spec'ed only for Jupiter and Saturn. The light of a half Uranus would be orders of magnitude less than sunlight, so it seems far out of the realm of possibility for those cameras.

so why did we get night shine on titania and ariel, but not miranda and umbriel?
miranda is closer to uranus then ariel and titania, so realistically it should have had stronger uranushine on miranda's night then titania and ariel, therefor making some of its night side features, like craters and cracks a bit clearer then ones on titania and ariel
onless uranus was in the wrong spot at the wrong time so we didn't see any uranusshine on miranda...



wait ted revealed some night shine on miranda, but i think there is more hidden from view like we should have seen more as voyager departed miranda, kinda like with triton when ted pulled out neptune shine on a triton image taken during departer
https://planetary.s3.amazonaws.com/image/mi...thnightside.jpg

you could also possibly pull some uranushine from https://upcimages.wr.usgs.gov/voyager/vg_00...5.thumbnail.jpg

and get some higher res uranushine from https://upcimages.wr.usgs.gov/voyager/vg_00...0.thumbnail.jpg and https://upcimages.wr.usgs.gov/voyager/vg_00...7.thumbnail.jpg


and for umbriel, did ted even tinker with that moon yet? because there is no umbriel night shine in this article
https://www.planetary.org/articles/1362


how did ted pull the neptune shine from triton images, and how did he pull uranusshine from titania, miranda, and ariel?
i want to see if i can try it myself and see if i can pull more uranushine from miranda and possibly oberon (altho i dout it that oberon has any visible uranusshine with what JRehling said)


---edit---
i made a map with miranda's night side with the map antdog found and ted's processed image

[JRehling]

I definitely committed the sin of posting based on seconds of mental arithmetic rather than something firmer, and Ted's images visibly contradict my guesstimates, so I got a little more serious about it.

First, the moons obviously differ in distance from Uranus, so the light they receive from it vary in this proportion.
If Oberon = 1 unit of luminance from Uranus, the others receive:

Miranda 20.5, Ariel 9.3, Umbriel 4.8, Titania 1.8.

Uranus is huge in each of their skies (22.7° at Miranda!) but seen in a half phase, which I estimate to be 1/4 of the light of a full Uranus, based on hard data from Venus, which is likewise a bland cloudy (and lambertian) ball. Of course, the sunlight at Uranus is 1/360 of that at Earth, but that is relative if we are comparing the sunlit portions of the moons with the uranus-lit.

In a nutshell, the uranus-shine is much brighter than, say, earthshine on the Moon in a given orbital configuration, as a fraction of sunlight at the respective distances from the Sun. In this respect, the half uranus shine on each moon is this ratio of full earthshine on a slender crescent Moon: Miranda 38, Ariel 17.5, Umbriel 9, Titania 3, Oberon 2. In absolute terms, the uranus shine is much dimmer than earthshine on the crescent Moon (divide all of those by 360).

What I fundamentally did not take into account is that the need to slew the spacecraft, a fact I'd known anecdotally, was only necessary for closer images. Full-disc images taken from a distance did not have such a requirement and the exposures were quite long – about 15 seconds. As you can see by snapping an image of the earthshine Moon with your pocket phone camera, getting earthshine in an image with the crescent is not so hard even with a short exposure and 15 seconds at Uranus (for, say, Oberon) is about the same at 0.1 seconds exposure of the Moon.

Note that with the Moon, it is difficult to capture earthshine on a photo of the half Moon or fuller phases because the glare of the sunlit portion destroys the earthshine portion. At Uranus, with those ratios of 2 to 38, that difficulty is overcome.

Now as for why any given image that seems like it might have shown uranusshine but did not, I would want to check on the albedo of that moon, the uniformity of albedo across its surface, and the exposure duration.

I hope this makes amends for my hasty and incorrect estimates before.

[TrappistPlanets]

I definitely committed the sin of posting based on seconds of mental arithmetic rather than something firmer, and Ted's images visibly contradict my guesstimates, so I got a little more serious about it.

First, the moons obviously differ in distance from Uranus, so the light they receive from it vary in this proportion.
If Oberon = 1 unit of luminance from Uranus, the others receive:

Miranda 20.5, Ariel 9.3, Umbriel 4.8, Titania 1.8.

Uranus is huge in each of their skies (22.7° at Miranda!) but seen in a half phase, which I estimate to be 1/4 of the light of a full Uranus, based on hard data from Venus, which is likewise a bland cloudy (and lambertian) ball. Of course, the sunlight at Uranus is 1/360 of that at Earth, but that is relative if we are comparing the sunlit portions of the moons with the uranus-lit.

In a nutshell, the uranus-shine is much brighter than, say, earthshine on the Moon in a given orbital configuration, as a fraction of sunlight at the respective distances from the Sun. In this respect, the half uranus shine on each moon is this ratio of full earthshine on a slender crescent Moon: Miranda 38, Ariel 17.5, Umbriel 9, Titania 3, Oberon 2. In absolute terms, the uranus shine is much dimmer than earthshine on the crescent Moon (divide all of those by 360).

What I fundamentally did not take into account is that the need to slew the spacecraft, a fact I'd known anecdotally, was only necessary for closer images. Full-disc images taken from a distance did not have such a requirement and the exposures were quite long – about 15 seconds. As you can see by snapping an image of the earthshine Moon with your pocket phone camera, getting earthshine in an image with the crescent is not so hard even with a short exposure and 15 seconds at Uranus (for, say, Oberon) is about the same at 0.1 seconds exposure of the Moon.

Note that with the Moon, it is difficult to capture earthshine on a photo of the half Moon or fuller phases because the glare of the sunlit portion destroys the earthshine portion. At Uranus, with those ratios of 2 to 38, that difficulty is overcome.

Now as for why any given image that seems like it might have shown uranusshine but did not, I would want to check on the albedo of that moon, the uniformity of albedo across its surface, and the exposure duration.

I hope this makes amends for my hasty and incorrect estimates before.

so why does miranda has less known uranusshine then ariel
and why is there no known uranusshine on umbriel if its partner titania had some