Starship Asterisk*

by **neufer** » Wed Feb 21, 2018 6:11 pm

Click to play embedded YouTube video.

geckzilla wrote:
Your eyes won't be able to see anything, but your camera should be able to. From what I understand, most digital cameras actually have a filter inside them to prevent infrared light coming in, because the sensor will pick it up, and there are some embarrassing things like shirts being slightly more transparent in infrared.

by **Chris Peterson** » Wed Feb 21, 2018 5:03 pm

ta152h0 wrote:If I buy an IR lens for a NIKON d3300, woul I be able to see anything thru the viewfinder ? My eyes surely cannot see infrared.Waste of money ?

What do you mean by an "IR lens"? There are such things as IR lenses for photographic cameras. They are designed such that near infrared which passes through them reaches the same focus as the visible light that passes through them. They used to be used with film that had sensitivity extending into the near IR, and now they're used with digital sensors with that sensitivity. Visually, these lenses look no different from ordinary camera lenses, and the view through the finder will be identical. All that will be different is that you'll get somewhat better near IR performance assuming your sensor has the necessary sensitivity. In fact, the D3300 has an IR blocking filter, but it can be removed, and if you do that you'll have a camera that produces odd colors, but images into the near IR.

If you actually mean an "IR filter", then whether you can see through it or not depends on its bandpass. If it is designed to block all visible light, it will look black. The plastic front of most TV remote controls is made of such material- transparent to near IR, opaque to visible light. A filter like that, used with a camera having near IR sensitivity, will produce interesting images of the world in ways somewhat different from how our eyes see things, even though you won't be able to use the optical viewfinder.

by **RJN** » Wed Feb 21, 2018 4:48 pm

Thanks to bystander for pointing several typos and an html error, all of which have now been fixed in the main NASA APOD. My apologies for the typos!

- RJN

by **geckzilla** » Wed Feb 21, 2018 4:42 pm

Your eyes won't be able to see anything, but your camera should be able to. From what I understand, most digital cameras actually have a filter inside them to prevent infrared light coming in, because the sensor will pick it up, and there are some embarrassing things like shirts being slightly more transparent in infrared.

by **neufer** » Wed Feb 21, 2018 4:33 pm

ta152h0 wrote:
If I buy an IR lens for a NIKON d3300, woul I be able to see anything thru the viewfinder ? My eyes surely cannot see infrared.Waste of money?

Not if you also purchase infrared film.

https://www.nikonimgsupport.com/ni/NI_article?articleNo=000002014&configured=1&lang=en_US wrote:
<<Infrared film is more sensitive to the infrared light spectrum than normal film, it can record both the visible light spectrum and infrared light above 700nm. There are several different films available each with different sensitivities to this light spectrum, Kodak, Ilford and Konica are companies who manufacture film specifically for infrared photography. This film can be used for many specialist applications, regular uses are aerial, astronomical, forensic, medical or general special effects photography. A filter is usually required for use with infra-red film, check recommended filters with film manufacturers.>>

by **ta152h0** » Wed Feb 21, 2018 4:24 pm

If I buy an IR lens for a NIKON d3300, woul I be able to see anything thru the viewfinder ? My eyes surely cannot see infrared.Waste of money ?

by **neufer** » Wed Feb 21, 2018 4:05 pm

geckzilla wrote:
Ann wrote:
But which bands or stripes are higher and which are lower in this image?
Piecing together bits of information from here and there, it would seem that the redder areas in this instance correspond to higher altitude areas while bluer areas correspond to areas of lower clouds.

The reddish Great Red Spot swirls at the end of a westward moving reddish South Equatorial Belt (SEB).

However the Great Red Spot is high in altitude while the South Equatorial Belt (SEB) is low.

https://en.wikipedia.org/wiki/Atmosphere_of_Jupiter#Great_Red_Spot wrote:
[b][color=#0000FF]Time-lapse visible sequence from the approach of Voyager 1 to Jupiter[/color][/b]
<<The upper ammonia clouds visible at Jupiter's surface are organized in a dozen zonal bands parallel to the equator and are bounded by powerful zonal atmospheric flows (winds) known as jets. The bands alternate in color: the dark bands are called belts, while light ones are called zones. Zones, which are colder than belts, correspond to upwellings, while belts mark descending gas. The zones' lighter color is believed to result from ammonia ice; what gives the belts their darker colors is uncertain.

Infrared data have long indicated that the Great Red Spot is colder (and thus, higher in altitude) than most of the other clouds on the planet; the cloudtops of the GRS are about 8 km above the surrounding clouds. It is not known exactly what causes the Great Red Spot's reddish color. Theories supported by laboratory experiments suppose that the color may be caused by complex organic molecules, red phosphorus, or yet another sulfur compound. In 2010, astronomers imaged the GRS in the far infrared (from 8.5 to 24 μm) with a spatial resolution higher than ever before and found that its central, reddest region is warmer than its surroundings by between 3–4 K. The warm airmass is located in the upper troposphere in the pressure range of 200–500 mbar. This warm central spot slowly counter-rotates and may be caused by a weak subsidence of air in the center of GRS.>>

by **geckzilla** » Wed Feb 21, 2018 2:57 pm

Ann wrote:Agreed. But which bands or stripes are higher and which are lower in this image?

Piecing together bits of information from here and there, it would seem that the redder areas in this instance correspond to higher altitude areas while bluer areas correspond to areas of lower clouds. Don't ask me about the poles, though. I still don't understand that. In visible light images, high altitude haze near the equator causes Rayleigh scattering, which results in some blue areas near Jupiter's limb, much like Earth has a bit of a blueish hue when the Sun is directly behind the viewer. It could just be the way Rayleigh scattering works in near-infrared bands.

by **Chris Peterson** » Wed Feb 21, 2018 2:55 pm

geckzilla wrote:Bruce, when infrared imagery shows warmer and cooler areas, I think that has more to do with infrared emission.

Yeah. The classification of "infrared" for a rather large part of the spectrum shorter than red is arbitrary, and in many ways confusing since it includes wavelengths which behave optically very much like the visible spectrum (today's image uses the same sensor and very similar filters to record red light and two slightly longer wavelengths) as well as wavelengths that are much longer and are typically produced by warm sources.

Your own image title of "Jupiter in Near-Infrared" is better than the APOD title, which removed the important qualification of "near" (although the distinction is maintained in the caption). Near infrared isn't emitted thermally until a body is quite hot (more than 3000° C for a peak emission at 800 nm).

by **Chris Peterson** » Wed Feb 21, 2018 2:42 pm

geckzilla wrote:They are real colors, though. They are translated from infrared into visible light. The longer wavelengths are represented by red, and the middle wavelengths are represented by green, and the shortest by blue.

We don't just do this with light, either. I've heard bat calls digitally translated from ultrasonic to sonic so we can get a sense of what they would sound like if we could hear higher frequencies. I've heard subsonic oscillations in the Sun digitally translated upwards so we can hear it ringing like a bell in a range our ears can respond to.

Most scientific instrumentation takes information that we can't directly sense and shifts it into a range we can.

by **De58te** » Wed Feb 21, 2018 10:08 am

Ann, I can imagine we having the same problems with the 8-year-old's questions about here on Earth. "Why is the sky blue at high noon, but the sky is red during sunset?" What would you answer?
"Well, science calls this phenomena Rayleigh Scattering."
8-year-old, "What's Rayleigh Scattering?"
"Well, according to Wikipedia, quote, Rayleigh scattering (pronounced /ˈreɪli/ RAY-lee), named after the British physicist Lord Rayleigh (John William Strutt),[1] is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. Rayleigh scattering does not change the state of material and is, hence, a parametric process. The particles may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle therefore becomes a small radiating dipole whose radiation we see as scattered light.
Rayleigh scattering of sunlight in the atmosphere causes diffuse sky radiation, which is the reason for the blue color of the sky and the yellow tone of the sun itself."

by **Boomer12k** » Wed Feb 21, 2018 9:26 am

Looks like an Opal....

:---[===] *

by **Ann** » Wed Feb 21, 2018 8:11 am

geckzilla wrote:They are real colors, though. They are translated from infrared into visible light. The longer wavelengths are represented by red, and the middle wavelengths are represented by green, and the shortest by blue. I would have told her that Jupiter looks different in this image because she is looking at it as a telescope capable of seeing light that she normally does not see would see it. So yes, it looks different, just as a color blind person sees the world differently. We are essentially all color blind.

Agreed. But which bands or stripes are higher and which are lower in this image?

Ann

by **geckzilla** » Wed Feb 21, 2018 7:48 am

Bruce, when infrared imagery shows warmer and cooler areas, I think that has more to do with infrared emission. In this case, we are still dealing with reflection, absorption, and scattering of the light, and the exposures are very short. If we could put Hubble on the shadowed side of the planet, I wonder how long the exposures would have to be to see anything?

It is interesting to me that the poles are bright at these wavelengths, while in near-uv, the poles are dark and the equatorial regions are bright. See:

by **BDanielMayfield** » Wed Feb 21, 2018 7:30 am

Here is how I would attempt to explain this odd but still lovely looking image.

'Jupiter looks strange because near infrared colors that our eyes cannot see have been sort of shifted into colors that we can see. While we can't see infrared, we can sometimes feel it as heat.

In this picture the red and blue colors are showing us where the warmer and cooler cloud tops of Jupiter are.'

If correct, something like that should work for most anyone.

Bruce

by **Guest** » Wed Feb 21, 2018 7:21 am

The "string of pearls" is amazingly consistant in size and spacing and latitude, it seems, i wonder why that it.

by **geckzilla** » Wed Feb 21, 2018 7:12 am

They are real colors, though. They are translated from infrared into visible light. The longer wavelengths are represented by red, and the middle wavelengths are represented by green, and the shortest by blue. I would have told her that Jupiter looks different in this image because she is looking at it as a telescope capable of seeing light that she normally does not see would see it. So yes, it looks different, just as a color blind person sees the world differently. We are essentially all color blind.

by **Ann** » Wed Feb 21, 2018 6:19 am

It is a quite beautiful image.

However...

Featured here in 2016, three bands of near-infrared light have been digitally reassigned into a mapped color image. Jupiter appears different in infrared partly because the amount of sunlight reflected back is distinct, giving differing cloud heights and latitudes discrepant brightnesess (that should be spelled brightnesses).

So Jupiter appears different partly because the amount of sunlight reflected back is distinct. Does that mean that if the amount of sunlight reflected back wasn't so distinct, Jupiter would look more familiar?

And Jupiter looks many-colored, as usual. But in this image the different colors are due to the fact that differing cloud heights and latitudes cause discrepant brightnesses. I feel enlightened.

But I suspect I would have some problems if a curious 8-year-old asked me about the picture:

8-year-old: Ann, why does Jupiter look so funny?

Ann (reading APOD caption): It's because the amount of sunlight reflected back is distinct.

8-year-old: What's distinct?

Ann (checking thesaurus): It means specific. Definite. Clear. Evident. Explicit. Express. Lucid. Manifest. Perspicuous. Sharp. Transparent. Trenchant. Unambiguous. Well-defined.

8-year-old: What's well-defined?

Ann: It means distinct. Shut up.

8-year-old: Why are there pink stripes on Jupiter?

Ann: They are a discrepant brightness.

8-year-old: What's discrepant?

Ann: It means different. Shut up.

8-year-old: Why are they pink?

Ann: They are mapped.

8-year-old: Like in geography class?

Ann: Shut up.

And that ends my highly impatient conversation with the 8-year-old. I could, of course, have told him (or her), that Jupiter is not really pink because the colors in the picture are mapped and therefore not real, and that the different colors mean different heights of the cloud tops. But if the kid had asked me how high the pink clouds are, or how high they are compared with the clouds that don't look pink, what could I have told him (or her)?

Ann

by **APOD Robot** » Wed Feb 21, 2018 5:06 am

Jupiter in Infrared from Hubble

Explanation: Jupiter looks a bit different in infrared light. To better understand 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 here in 2016, three bands of near-infrared light have been digitally reassigned into a mapped color image. Jupiter appears different in infrared partly because the amount of sunlight reflected back is distinct, giving differing cloud heights and latitudes discrepant brightnesses. Nevertheless, many familiar features on Jupiter remain, including the light zones and dark belts that circle the planet near the equator, the Great Red Spot on the lower left, and the string-of-pearls storm systems south of the Great Red Spot. The poles glow because high altitude haze there is energized by charged particles from Jupiter's magnetosphere. Juno has now completed 10 of 12 planned science orbits of Jupiter and continues to record data that are helping humanity to understand not only Jupiter's weather but what lies beneath Jupiter's thick clouds.

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