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This is a picture (mosaic?) of Jupiter's south pole taken by Juno (also shown below). It has gotten a lot of press, but I haven't seen anything, even in the scientific paper that accompanied its release, that answers the first question that came to mind when I saw it : is this a view into the inside of Jupiter? I seem to recall seeing IR images of Jupiter where the poles appear quite hot, which would be consistent with a "clear sky" providing a view of deeper, hotter layers. But how deep can see in this picture?

enter image description here

Edit: I am aware that this is a visible light image, and that visible light does not penetrate the cloud layer of Jupiter.

My question is whether part of the south pole of Jupiter is cloud-free, at least to a depth where atmospheric extinction limits our ability to see the clouds. This interpretation of the picture would assume that blue light penetrates deeper than red light into the atmosphere (clouds not included) of Jupiter, and that this is the reason that some of the clouds, presumed to be deeper, look blue, while some areas between them are essentially black.

Here is an example of a picture of Jupiter in IR, which shows the poles as being relatively hot. The troposphere of Jupiter (or any planet) is generally hotter the deeper you go, so the poles appearing hotter is consistent with less cloud cover at the poles. [description]

I'm aware that perhaps no-one, including the Juno team, knows the answer to my question. Some useful partial answers would include an estimate of the depth to which visible light could penetrate Jupiter's atmosphere in the absence of clouds, and whether blue light would penetrate deeper than red.

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  • $\begingroup$ I don't want to answer, as I only know a little, but that looks like a visible light image, so, not very deep at all. Basically just the surface up to the point where the visible light transparency ends, or not very far. Infra-red imaging sees deeper into the planet. I think, still not very deep but deeper. That doesn't appear to be an IR image. If anyone knows more specifics, feel free to expand on this in an answer. $\endgroup$ – userLTK Sep 16 '17 at 21:42
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userLTK's comment is correct, you cannot see very deep at all.

Information about the image

First off, there are three imagers on the Juno spacecraft: JunoCam, UVS, and JIRCAM. You can see a full list of instruments here. JunoCam is described as a:

visible-light camera/telescope of the Juno Jupiter orbiter, a NASA space probe launched to the planet Jupiter on 5 August 2011. It was built by Malin Space Science Systems. The telescope/camera has a field of view of 58 degrees with four filters (3 for visible light).

The image you're seeing was taken by JunoCam and is a visible image. In fact, this image is combined by images taken over multiple days and from multiple orbits to get different vantage points and show all areas lit up. It isn't however a mosaic $-$ the 58 degree field of view allows JunoCam to image the entirety of Jupiter in one image. Instead, this image is simply the carefully crafted combination of many different images of the south pole.

FWIW, UVS is an imager in the ultraviolet and JIRAM is an imager in the infrared.

How deep are you seeing into Jupiter?

Not very deep at all. Because the image is in the visible spectrum, the depth into Jupiter before it becomes too opaque is going to be very, very short. You may not even be seeing down to Jupiter's "surface" where the atmospheric pressure equals 1 bar.

Incidentally, JIRCAM can see down to about 5-7 bars if its lucky, enough to penetrate the very upper layers of the atmosphere.

Infrared images of the poles

Obviously I can't be certain what you saw before concerning infrared images of Jupiter's poles, but my guess is they may have been something like the image below. This image was taken by JIRAM

enter image description here

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  • $\begingroup$ If I understand correctly, you are saying that visible light does not penetrate very far through Jupiter's bulk atmosphere. Is this why the clouds at the south pole look blue, i.e. they are at a (somewhat) lower altitude than the cloud tops at lower latitudes, so we are looking at them through a thicker layer of atmosphere, and this makes them look blue? If this is the case, then the black areas would be spots where we our vision is limited by atmospheric attenuation rather than by clouds. Is that accurate? $\endgroup$ – brendan Sep 17 '17 at 13:07
  • $\begingroup$ @brendan Yes, visible light cannot easily penetrate Jupiter's thick clouds and thus the light you're seeing in the image is from very near the surface, basically the tops of the clouds. As for the color, I can't definitively say what is causing it (and likely nor can others). The color of the clouds is entirely caused by the content in the clouds. The white/red colors in the bands of Jupiter are believed to be caused by ammonia but we're not even sure about that and we've been studying that much longer. $\endgroup$ – zephyr Sep 17 '17 at 20:43
  • $\begingroup$ @brendan Keep in mind also, that while that image is a true-color image of Jupiter's pole (that is, it actually is blue), its also been enhanced to appear much more vivid that it probably would to the naked eye. $\endgroup$ – zephyr Sep 17 '17 at 20:44
  • $\begingroup$ Apparently I did not make my question clear enough. I know that it is a visible light image, and I know that visible light does not penetrate clouds (on Jupiter or elsewhere). My question is about whether there is or is not complete cloud cover in the image. $\endgroup$ – brendan Sep 20 '17 at 12:08
  • $\begingroup$ @brendan There has to be. There's nothing on Jupiter but clouds. What exactly would you expect to see if there wasn't complete cloud cover? You'd only see more clouds. $\endgroup$ – zephyr Sep 20 '17 at 13:34

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