Astronomy / Space Does anyone know if the photos of Saturn's rings are taken with very long exposure?

[BEKTOP 3APEMOB]

This is an image from nasa page:

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Another one - mosaic from Cassini footage:

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I'm sorry for huge images, but bear with me.
Here is what I'm talking about -look at this star sky shot:

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And now this one - taken with long exposure:

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See what I'm getting at - If for some technical reason they had to take photos of rings with long exposure, then the actual view (naked eye) of these rings from about the same distance as Cassini is now will be very different.

Does anyone here know the shutter speeds of Cassini's camera out of the back your head? Or should I try diving a bit deeper into this?

 

[CMDR Moortz]

Saturns rings are not an effect of a camera exposure. You can see them through a telescope.

 

[Surfinjo]

Also, photos from Space are taken in layers, where each layer is very low resolution, but added to numerous layers of the same area, build up the picture.

This is one of the many reasons why the TV stories where some government agency can get live action satellite images of some bad guy on the ground, is just science fiction.

Looking at the images of Saturn and its rings though, the overall resolution seems very high. While the rings do appear almost solid on Earth and will appear pretty dense close by, they are made up if numerous rocks and dust, so it is reasonable to expect the detail to show a little, but this will be lost by the number of layers needed to build a clear image.

This is further emphasised by short clips which have been released of various prominent features that occasionally appear on the rings. The clip will show the feature jumping from one point to the next, rather than the smooth movement of reality. The rings are enormous is size, the Earth is dwarfed in comparison. So each of these jumps will represent and enormous degree of arc. The time between each frame will be considerable.

 

[BEKTOP 3APEMOB]

Saturns rings are not an effect of a camera exposure. You can see them through a telescope.

I know they aren't an effect, what I don't know is how they would actually look from closer distance (think nearest and farthest moon of Saturn distances)?

Also, photos from Space are taken in layers, where each layer is very low resolution, but added to numerous layers of the same area, build up the picture.

This is one of the many reasons why the TV stories where some government agency can get live action satellite images of some bad guy on the ground, is just science fiction.

Looking at the images of Saturn and its rings though, the overall resolution seems very high. While the rings do appear almost solid on Earth and will appear pretty dense close by, they are made up if numerous rocks and dust, so it is reasonable to expect the detail to show a little, but this will be lost by the number of layers needed to build a clear image.

This is further emphasised by short clips which have been released of various prominent features that occasionally appear on the rings. The clip will show the feature jumping from one point to the next, rather than the smooth movement of reality. The rings are enormous is size, the Earth is dwarfed in comparison. So each of these jumps will represent and enormous degree of arc. The time between each frame will be considerable.

Creating a hi-res picture by layers equals to long exposure for our purposes. So it's still unclear for me how I would see those rings if I were standing(orbiting) where Cassini is now or somewhere around.

 

[Surfinjo]

I know they aren't an effect, what I don't know is how they would actually look from closer distance (think nearest and farthest moon of Saturn distances)?


Creating a hi-res picture by layers equals to long exposure for our purposes. So it's still unclear for me how I would see those rings if I were standing(orbiting) where Cassini is now or somewhere around.

Perhaps, but it isn't the same is it?

If you were nearer to the rings you would see them as a huge plane of rocks, which is what they are.

 

[Ryohei56]

I think the reality (viewing from, say, a distance of 2x the diameter of the rings) would be rather dull in terms of colour. Saturn is so much further from the Sun so the light levels falling on the rings and the cloud tops (which is pretty well all we can see) will be correspondingly lower. Think of the same scene viewed on a day of full sunshine and then on an totally overcast day, that's not a perfect analogy but it'll do. I've viewed Saturn through my 8-inch scope and have also imaged it. The unprocessed images and also the "naked eye" views are relatively dowdy in appearance. Jupiter turns out much the same.

However - if NASA would like to send me out there to check for myself, I can do next Monday?

 

[Surfinjo]

I think the reality (viewing from, say, a distance of 2x the diameter of the rings) would be rather dull in terms of colour. Saturn is so much further from the Sun so the light levels falling on the rings and the cloud tops (which is pretty well all we can see) will be correspondingly lower. Think of the same scene viewed on a day of full sunshine and then on an totally overcast day, that's not a perfect analogy but it'll do. I've viewed Saturn through my 8-inch scope and have also imaged it. The unprocessed images and also the "naked eye" views are relatively dowdy in appearance. Jupiter turns out much the same.

However - if NASA would like to send me out there to check for myself, I can do next Monday?

Wish you luck on that one. But wouldn't it be a bummer if they send you a letter by snail mail saying they were considering you but took someone else, because the take off was Tuesday!

Colour images of deep space are generally what are called false colour. The colours added based upon data collected using other instruments.

As Earth bound humans we are used to observing things, primarily with vision. Objects in space tend to be viewed principally with other, more sensitive and accurate instruments. Humans have quite limited vision and most of the objects that are featured might be missed.

Anyone remember the time that rings on Uranus and Neptune were discovered? The images from the Voyager, I think it was 2, were quite a surprise.

 

[Kheran]

Regarding the colors of Saturn, they are quite obvious through amateur equipment, like I own. Here is a shot taken with a small high speed CCD and a 355 mm ( 14" ) diameter telescope :

 

[Surfinjo]

Regarding the colors of Saturn, they are quite obvious through amateur equipment, like I own. Here is a shot taken with a small high speed CCD and a 355 mm ( 14" ) diameter telescope :

A rather different image than those taken by onboard imaging equipment on spacecraft. The colours are different. But more importantly, the image was taken with a relatively large, heavy camera on a long exposure. Those on space craft are taken using electronic imaging, with very low resolutions, repeatedly then assembled together and adapted electronically on Earth.

Every gram of payload adds enormous amounts to cost. There is little point in installing a lot of imaging equipment since little information can be gathered. Such imaging that exists is low resolution for compound images.

The same reason why there is little scientific justification in sending humans to Mars or space at all for that matter. All the actual work can be better performed by automated machines. But telling taxpayers stories of how these astronauts are pioneers, setting forth on some sort of patriotic, cosmic adventure, to spread democracy throughout the galaxy are intended to ensure funding.

Remember also that the Hasselblad cameras on Voyagers could read a headline on a newspaper at a kilometre at pin sharp resolution.

Sorry, but that's not true. Sounds a lot like the claim, in the early 70s, that American spy satellites could read the second hand of a Sekonda Watch of a Russian walking across Red Square.

 

[ZoltanSnarf]

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Hope that helps.

(My assumption is that's just what they look like.)

 

[Surfinjo]

http://www.astro.cornell.edu/~randerson/Inreach Web Page/inreach/saturn.html

The mistakes being made here are of perspective.

The width of the rings of Saturn, are about 282000 km while the width of the Earth is about 12750 km. A factor of 23.5 or there about.

The planet itself is about 19 times the width of the Earth, plus rings on either side, looking at the photo above, posted by Kheran, we are looking at a span, 66 times the width of the Earth.

As a comparative, if we look at an image of the Earth, showing the whole Earth, details are almost impossible to make out. It is simply a number of outlines surrounded by blue.