APOD: Jupiter in Ultraviolet from Hubble (2018 Oct 16)

[APOD Robot]

Jupiter in Ultraviolet from Hubble

Explanation: Jupiter looks a bit different in ultraviolet light. To better interpret Jupiter's cloud motions and to help NASA's robotic Juno spacecraft understand the planetary context of the small fields that it sees, the Hubble Space Telescope is being directed to regularly image the entire Jovian giant. The colors of Jupiter being monitored go beyond the normal human visual range to include both ultraviolet and infrared light. Featured from 2017, Jupiter appears different in near ultraviolet light, partly because the amount of sunlight reflected back is distinct, giving differing cloud heights and latitudes discrepant brightnesses. In the near UV, Jupiter's poles appear relatively dark, as does its Great Red Spot and a smaller (optically) white oval to the right. The String of Pearl storms farther to the right, however, are brightest in near ultraviolet, and so here appear (false-color) pink. Jupiter's largest moon Ganymede appears on the upper left. Juno continues on its looping 53-day orbits around Jupiter, while Earth-orbiting Hubble is now recovering from the loss of a stabilizing gyroscope.

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[Ann]

I find the mapped colors quite confusing. For example, why are the string or pearls colored pink, when they are the most ultravolet-bright objects on the surface of Jupiter? Aren't ultraviolet-bright objects traditionally mapped as blue, or perhaps violet? In any case, wouldn't it be best to make the string of pearls look really bright, by making them look brilliantly white?

And how can we tell the difference between ultraviolet-bright objects and infrared-bright objects in this map? What do the colors mean?

Ann

[geckzilla]

And how can we tell the difference between ultraviolet-bright objects and infrared-bright objects in this map? What do the colors mean?

The pinkish areas are reflecting blue light more, and near-uv light a bit less. The bluest areas are reflecting the near-uv wavelengths at ~225nm the most. Cyan areas reflect a broader range of near-uv light from ~275-225nm. Whiteish areas reflect the wavelengths more evenly. The poles don't seem to reflect much near-uv light at all, while the equatorial regions show a lot of scattering of the shorter wavelengths. So the colors are just showing what wavelengths are being absorbed, reflected, and possibly emitted, though I don't suspect much, if any, emission is seen here.

Can I write a more generic description of color? Sheesh. Sorry I don't know more. Probably would need to study atmospheric physics and chemistry to be of any use.

[Ann]

And how can we tell the difference between ultraviolet-bright objects and infrared-bright objects in this map? What do the colors mean?

The pinkish areas are reflecting blue light more, and near-uv light a bit less. The bluest areas are reflecting the near-uv wavelengths at ~225nm the most. Cyan areas reflect a broader range of near-uv light from ~275-225nm. Whiteish areas reflect the wavelengths more evenly. The poles don't seem to reflect much near-uv light at all, while the equatorial regions show a lot of scattering of the shorter wavelengths. So the colors are just showing what wavelengths are being absorbed, reflected, and possibly emitted, though I don't suspect much, if any, emission is seen here.

Can I write a more generic description of color? Sheesh. Sorry I don't know more. Probably would need to study atmospheric physics and chemistry to be of any use.

Geck, I really hope I don't say anything offensive here, but in my opinion blue objects look blue either because they specifically reflect blue (or green to ultraviolet) light more than they reflect yellow to red light, or else they look blue because they emit blue light. That's why I find pink a weird color to represent ultraviolet light. But mapped color is mapped color, so really pink is just a good as any other color here.

Then again, you just explained to me that blue objects that don't emit much ultraviolet light can be considered "red from an ultraviolet point of view". I can understand that, of course. That still doesn't explain the pink color of the most ultraviolet objects on Jupiter. Perhaps the color was chosen arbitrarily.

My main complaint is that today's caption doesn't explain what the different colors mean. Thanks for telling me about it, I really appreciate it, but I would prefer that the caption told me.

Ann

[Boomer12k]

Reminds me of an Opal...

My best Jupiter shot with Meade color planetary camera...a bit darkened for contrast and detail...

It is interesting that the poles look very similar in today's APOD...as they don't seem to reflect much light...and i suppose rightly so for the angles they are at... if that be the case...

:---[===] *

[BDanielMayfield]

Reminds me of an Opal...

My best Jupiter shot with Meade color planetary camera...a bit darkened for contrast and detail...

It is interesting that the poles look very similar in today's APOD...as they don't seem to reflect much light...and i suppose rightly so for the angles they are at... if that be the case...

:---[===] *

That's an excellent photograph Boomer!

So if a teacher were to tell young students, 'this is how Jupiter would look if we had ultraviolet vision', would it be an accurate statement?

Bruce

[heehaw]

Surprised not to see aurorae at the two poles!

[geckzilla]

And how can we tell the difference between ultraviolet-bright objects and infrared-bright objects in this map? What do the colors mean?

The pinkish areas are reflecting blue light more, and near-uv light a bit less. The bluest areas are reflecting the near-uv wavelengths at ~225nm the most. Cyan areas reflect a broader range of near-uv light from ~275-225nm. Whiteish areas reflect the wavelengths more evenly. The poles don't seem to reflect much near-uv light at all, while the equatorial regions show a lot of scattering of the shorter wavelengths. So the colors are just showing what wavelengths are being absorbed, reflected, and possibly emitted, though I don't suspect much, if any, emission is seen here.

Can I write a more generic description of color? Sheesh. Sorry I don't know more. Probably would need to study atmospheric physics and chemistry to be of any use.

Geck, I really hope I don't say anything offensive here, but in my opinion blue objects look blue either because they specifically reflect blue (or green to ultraviolet) light more than they reflect yellow to red light, or else they look blue because they emit blue light. That's why I find pink a weird color to represent ultraviolet light. But mapped color is mapped color, so really pink is just a good as any other color here.

Then again, you just explained to me that blue objects that don't emit much ultraviolet light can be considered "red from an ultraviolet point of view". I can understand that, of course. That still doesn't explain the pink color of the most ultraviolet objects on Jupiter. Perhaps the color was chosen arbitrarily.

My main complaint is that today's caption doesn't explain what the different colors mean. Thanks for telling me about it, I really appreciate it, but I would prefer that the caption told me.

Well, it wasn't any more arbitrary than a regular visible light image. The shorter wavelengths are represented by the bluer color, while the longer are represented by a redder color. It is just an honest to goodness picture of Jupiter in a certain slice of the electromagnetic spectrum. There are no tricks and no decision to change anything because it looked better or worse to me. I balanced the color, that's it. I'm only sorry you can't get over your prejudice to enjoy things sometimes.

[Ann]

Well, it wasn't any more arbitrary than a regular visible light image. The shorter wavelengths are represented by the bluer color, while the longer are represented by a redder color. It is just an honest to goodness picture of Jupiter in a certain slice of the electromagnetic spectrum. There are no tricks and no decision to change anything because it looked better or worse to me. I balanced the color, that's it. I'm only sorry you can't get over your prejudice to enjoy things sometimes.

I'm sorry, Geck. I didn't know, or notice, that it was you that processed it. As you know, I know nothing about either astrophotography or processing.

I'll shut up now.

Ann

[Cousin Ricky]

So if a teacher were to tell young students, 'this is how Jupiter would look if we had ultraviolet vision', would it be an accurate statement?

How it would look would depend on how one’s photoreceptors would respond to which wavelengths of ultraviolet, and how one’s brain would process those signals. Perhaps in some neural configuration it would look like this photo, but you cannot categorically assert that this is how it would look.

There is also the qualia problem. We just can’t say.

[spacehappy]

Doesn't anyone notice the bright spot on Ganymede? Almost looks like Io.

[neufer]

---

Doesn't anyone notice the bright spot on Ganymede?

NASA / JPL / Justin Cowart

Voyager 2 Ganymede mosaic: Osiris crater

19 frame mosaic of Ganymede taken during Voyager 2's flyby of the moon on July 9, 1979.

This image is centered on the bright Osiris Crater and surrounding ejecta deposits.

[MarkBour]

I wonder if there are any similar images of Earth?
OR
a three-part shot, like one of the images linked -- 3 simultaneous shots of Earth from space in UV, visible, and IR ?

IF the Great Red spot on Jupiter appears that dark in UV, then it absorbs UV pretty well, rather than reflecting it, right?

[edgardine]

I'll shut up now.

Ann

Please no, don't shut up. I came on this page hoping for your comment, and the fact that you led geckzilla to explain a bit more was interesting.

[samuelzi]

Why does Ganymede look like a marble?

[neufer]

Click to play embedded YouTube video.

Why does Ganymede look like a marble?

[BDanielMayfield]

So if a teacher were to tell young students, 'this is how Jupiter would look if we had ultraviolet vision', would it be an accurate statement?

How it would look would depend on how one’s photoreceptors would respond to which wavelengths of ultraviolet, and how one’s brain would process those signals. Perhaps in some neural configuration it would look like this photo, but you cannot categorically assert that this is how it would look.

There is also the qualia problem. We just can’t say.

Good reply. "We don't really know" is so often the most accurate answer.

[Chris Peterson]

So if a teacher were to tell young students, 'this is how Jupiter would look if we had ultraviolet vision', would it be an accurate statement?

How it would look would depend on how one’s photoreceptors would respond to which wavelengths of ultraviolet, and how one’s brain would process those signals. Perhaps in some neural configuration it would look like this photo, but you cannot categorically assert that this is how it would look.

There is also the qualia problem. We just can’t say.

Good reply. "We don't really know" is so often the most accurate answer.

For young students, however, I think in this case the correct answer is "yes".

[RJN]

The parenthetical words "(not pictured)" have now been added to the text of the main NASA APOD to clarify that the image featured does not include infrared light. We apologize for any confusion. - RJN