Can you elaborate? What else needs to be taken into account? Or is it just that a rotating frame cannot be analyzed this way?
Sadly, I can’t. I think that the problem is that you need to consider Coriolis effects, too, which can’t be neatly encapsulated in an effective potential… but it’s been over a decade since I looked at the problem at all, and even then I didn’t look at it in all that great detail.
The website says temperature readings are reported daily, which might explain their stability over the last 24 hours. 
I find it interesting how they are using it a lot for relatively close objects. Exploration beyond our solar system is what fascinates me.
Well, both are pretty fscinating. We are going to learn a lot about our near neighborhood and a whole lot of new planetary information we never had before.
But year, exoplanets are exciting, and we’ll learn a lot about their composition and atmospheres.
One thing I don’t think people know about JWST: despite having a much larger mirror than Hubble it will have about the same angular resolution because it’s dealing with longer wavelengths of light. Somdo 't expect detailed pictures of exoplanets - they will still be a point source to JWST. This scope is all about observing in the near and medium infrared.
The JWST has deployed its heat shield successfully, meeting a major milestone. Next is that the shield layers need to be tensioned. This may start in the next couple of days.
How do they know if the deployments have been successful ?
(I reckon they must have a camera up there they’re not telling us about !)
Or are they just thinking “so what - there’s nothing we can do if they don’t work”
They know if deployment is successful based on telemetry
They do not have a camera on the telescope because that would add weight and complexity.
And yes, if it doesn’t work there’s nothing they can do.
I’m sure a small camera would be lighter & less complex than a bunch of telemeters.
It could show you exactly what’s going on - especially if it’s something unexpected
like … a space owl perching on one of the protuberances or something.
During the design phase, some remarkable advances were made in space owl spectrometry that obviated the need for a camera with its bulky lens
I feel like every time I’ve heard or read about the JWST over the past few years, the primary purpose was to “see” galaxies and stars from the earliest period of the universe; times and places that weren’t observable with the current telescopes. But perhaps NASA and ESA want to begin with “low hanging fruit” to get some easy wins early in the game?
I assume that marketing and communication is a huge part of NASA’s strategy, as future projects are somewhat dependent on the government’s and public’s perception of the value and success of any project. Part of that may be understanding what’s more interesting, appealing and understandable to the masses.
Far off galaxies and the Big Bang and such are all fine, but even if it’s not the primary purpose of the JWST, I’m most interested in what it will see in this solar system and others regarding habitability and even life on other planets. Life on other planets is still The Big One, IMO, in terms of potential scientific discoveries out there in the universe. I’m glad it will have some capabilities in that regard.
I haven’t heard of this as a goal for the telescope, but I’m easily amused and think it amazing to see resolved disk images of stars other than the Sun. But the images to date are of poor quality. Many of us grew up thinking that distant stars would never be imaged as anything other than points, so even this has been quite the accomplishment.
Since the stars that have (or should have) the biggest apparent disks tend to be red giants such as Betelgeuse or Antares, with plenty of radiation in JWST’s sweet spot, I wonder if those would be suitable eye candy that are also quick wins? Am I right to think JWST would have higher resolution than any other telescope that has delivered resolved star disk images? Or, perhaps, are the biggest apparent disk sizes always on stars that are too powerful and close, and therefore too bright, to be suitable targets for JWST?
If you’re interested,
Yep. It’s a way to check things out, make adjustments, and test systems. Also, no reason not to use it for closer objects, too. There’s a lot to investigate and learn about both close and far.
Um… yes and no? Apparently resolution isn’t just a matter of how big the telescope mirrors are but also the wavelength of light being used. And that’s about the extent of what I know, I am in no way equipped to do the math on that sort of thing.
Yes, definitely this, for a scope that is diffraction limited. However, we could stipulate red light, which dominates red giant light and is available to JWST, so in the case of imaging red giants it could make no difference. There could be other issues, like whether active correction in Earth based scopes can get them to the diffraction limit, and whether there are any other limiting factors. What I really lack is an overarching sense of how well Earth based scopes can work, I guess.
“Ground-based Optical/Near-Infrared large Telescopes are crucial tools for the understanding of our Universe, but their image quality is severely limited by the (quasi-static) errors in the telescope itself and the (very dynamic) atmospheric turbulence inside and over the telescope. Active Optics is used to overcome the first limitation and Adaptive Optics the latter, giving ultimately images near the diffraction limit of the primary mirror. There are a number of physical limitations to adaptive optics performance, leading to successive generations of more and more sophisticated techniques detailed below.”
I mentioned in the post above that JWST has about the same resolution as Hubble, only in the infrared.
Ground based telescopes surpassed Hubble for resolution years ago because of adaptive optics. The new Thirty Meter class telescopes will have far better resolution than Hubble or JWST. But because the atmosphere absorbs IR, we need space telescopes to obaerce 8n the infrared.
Space scopes are also better for spectroscopy, because they don’t have to worry about atmospheric effects distorting the spectrum of observed targets.
JWST also has a coronagraph which can block the light of a star in a system, allowing us to observe faint details in that system such as directly observing exoplanets or perhaps characterizing dust and such.
But in terms of seeing detail, the largest Earth telescopes are better than JWST.
Calibration, I suspect. The distant observations will come later.
that was going to be my guess. Something close that might also be interesting.
While technically more or less true, it does depend on the wavelengths being observed, and there is some overlap with Hubble: Hubble can observe in the near-infrared, while Webb does have the capability to observe in the longer wavelengths of visible light, mainly red and orange.
But there are additional factors that are even more important. The difference in size between the JWST and the Hubble mirrors is just huge, which means, irrespective of resolution, the JWST has much greater light-collecting power and NASA has said it should be able to see objects 10 to 100 times fainter than what Hubble can see.
Another important attribute for giving us more information about exoplanets and the signatures of possible life is that the JWST will be capable of something called imaging spectroscopy, where every pixel of the image contains spectrographic information. It’s this capability, I suspect, that will give Webb unprecedented power to do spectrographic analysis of the atmospheres of suitably situated exoplanets.
