JWST/HST images of Uranus and Neptune |
JWST/HST images of Uranus and Neptune |
Feb 14 2019, 09:16 PM
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Member Group: Members Posts: 708 Joined: 1-April 08 From: Minnesota ! Member No.: 4081 |
Amazing new images from Hubble Space Telescope (HST) of Uranus and Neptune! https://earthsky.org/space/hubble-space-tel...-uranus-neptune
Here are the Hubble site images: http://hubblesite.org/images/news/release/2019-06 |
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Feb 18 2019, 08:45 PM
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#2
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Member Group: Members Posts: 708 Joined: 1-April 08 From: Minnesota ! Member No.: 4081 |
From the OPAL site the images of Uranus are taken with the WF3-UVIS filter camera on Hubble and are not IR images. There are 63 UVIS(ultra violet-visual) filters http://www.stsci.edu/hst/wfc3/ins_performa...ponents/filters. My guess is that the images published were from the F845 filter which shows the N polar cap AND the compact methane ice cloud at the polar cap edge https://solarsystem.nasa.gov/news/839/hubbl...uranus-neptune/
As the compact cloud is considered an upper atmospheric phenomenon (sometimes visible in amateur telescopes) and the large polar cap is not a high troposphere or stratospheric phenomenon, that a visible light view of Uranus might still appear relatively bland! With the north polar cap of Uranus facing the sun however one wonders whether it might become visible as the planet’s summer progresses. |
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Feb 18 2019, 09:41 PM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
The F845 filter is certainly what I'd call infrared, whatever bin they happened to organize it into. There may be no exact sharp cutoff of the longest wavelength a human eye can see, but I don't think anyone considers >800nm to be red as opposed to IR.
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Feb 18 2019, 10:41 PM
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#4
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Member Group: Members Posts: 708 Joined: 1-April 08 From: Minnesota ! Member No.: 4081 |
The F845 filter is certainly what I'd call infrared, whatever bin they happened to organize it into. There may be no exact sharp cutoff of the longest wavelength a human eye can see, but I don't think anyone considers >800nm to be red as opposed to IR. Excellent point! Looking a bit further that filter spans the 8K to 9K bandwidth; might be better in the IR bin! Will have to look further as to exactly how that image was created. Does your colorized image in your figure above approximate what the human eye would see? |
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Feb 18 2019, 11:40 PM
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#5
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
No, I see absolutely no features in Uranus with the naked eye, and I'm not sure that anybody ever has with any telescope. There are certainly bright white storms that appear at times, but they push the limits of resolution. While the gradient in red can in principle be seen with the human eye, it is drowned out by overwhelmingly higher levels of brightness in blue and green. When I add the red plane to the blue and green in Photoshop, I can hardly even notice its presence (which is why I doubled it to make that image above).
I think at the limits of terrestrial telescope, Uranus is a blank disc, and I've seen it many times. It's a very appealing color, but that's all one sees. From a vantage point inside the Uranus system, the enormous increase of resolution might make the slight contrast in color emerge. Here is a conventional RGB color image that I took in 2016. This is basically what it looks like to my eye.
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