James Webb Space Telescope, information, updates and discussion |
James Webb Space Telescope, information, updates and discussion |
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![]() Member ![]() ![]() ![]() Group: Members Posts: 134 Joined: 13-March 05 Member No.: 191 ![]() |
The manufacture of the JWST mirror blanks has now been completed.
Despite this milestone, the fate of JWST is still somewhat precarious, because although the scientific bang from the telescope is expected to be huge, the bucks required have increased to a staggering $4.5 billion. A Space.com article on the squeeze in NASA's space-based astronomy plans gives some background. The JWST home page can be found here. The Space Telescope Science Institute, which runs Hubble, also has a site here. As does ESA. |
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#2
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 ![]() |
A Webb Uranus image from April 2023.
And what do we make of that bright, bright cloud at 8:30 on the limb? -------------------- |
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#3
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Member ![]() ![]() ![]() Group: Members Posts: 237 Joined: 14-January 22 Member No.: 9140 ![]() |
It's important to remember how sensitive these details are to the choice of wavelength, and comparing JWST images to those from other, seemingly-comparable telescopes, and be misleading, and I think this is actually a great example of it.
Uranus is very dark in certain IR wavelengths that are absorbed by methane. Among the many wavelengths available to JWST, the rings are comparatively much brighter in some of those, and high, "white" clouds may also be much brighter. The ratios can be much more dramatic than in images from Voyager, Hubble, or Keck. And I think that's the real story here. Probably nothing here is actually different from what was going on with Uranus at the time that images were being captured by Hubble and Keck, but the IR is showing us something very different. And then the people who are making the aesthetic choices in how to present the imagery are maybe doing something subtly deceptive by producing outputs that almost resemble the way we've been used to seeing Uranus and Neptune with these rare, isolated differences. |
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