I am curious to know whether the James Webb Space Telescope will be able to take pictures of our own planets like Jupiter / Saturn like Hubble did.
If yes, then how different are these images expected to look from those of Hubble, as Webb is optimized for infrared?
JWST must forever be oriented to remain in the shadow of its own sun shield, so that it remains cool and sensitive to the low temperatures of deep space, limiting what can be observed. Notably, it cannot look inwards in our solar system towards the sun or inner planets, nor can it orient to look directly away from the sun, but outer solar system objects will be observable some of the time. Details about what JWST can look at are disclosed in the Technical FAQ Specifically On Solar System Observations
Some things in our outer solar system that JWST may observe are listed in detail at SOLAR SYSTEM PROGRAM INFORMATION. Included there are:
As for how JWST is different from Hubble, consider reading Webb vs Hubble. You've already identified it sees further into the infrared range of the spectrum, and less of the visible spectrum. So its images of objects in our solar system will necessarily be presented to us with false-colour.
(source)
JWST has superior ability to sense temperature and chemical structure, and as such it will do a good job of telling us what things are made of and will provide insight into their chemical processes.
For example, regarding observations of Uranus and Neptune:
“The key thing that Webb can do that is very, very difficult to accomplish from any other facility is map their atmospheric temperature and chemical structure,” ... Crucially, Webb can distinguish one chemical from another. [source]
Therefore, I expect the majority of false-colour images of planets in our solar system to be colourized in a way that calls attention to different chemicals (e.g. assigning individual colours to oxygen, hydrogen, ammonia etc.). This example below shows how three near-infrared wavelengths of 756 nm, 727 nm, and 889 nm (methane) are combined into a false-colour image as compared to visible spectrum. This shows methane as blue.
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Hubble's vision extends to 2500 nm, whereas JWST sees wavelengths as long as 28500 nm.
It's hard to imagine how different the images will look until we see them (we're all as excited as you!), and each image will be different depending on the science being done, because there's no default way to map IR wavelengths to visible wavelengths for the purposes of general presentation. Images posted in galleries may be processed just to give them visual appeal. There's a certain amount of artistry involved here. But to give you an idea how how intense the contrast can be at certain wavelengths, here's an infrared terrestrial view (from Hawaii) of Jupiter at just 4680 nm. Predominantly this image is giving us a sense of temperature, something JWST will excel at.
(source)
Here's NASA's site with an overview of already approved Solar System science missions for JWST: https://www.stsci.edu/jwst/science-execution/approved-programs/cycle-1-go
If you click on the red number to the left of each table entry, you can read an executive summary of what is intended to be done.
I'm myself surprised by how much Solar System science it will do! Okay, I don't see anything about Jupiter or Saturn in the first batch. Those are too easy for JWST. It will put its eye on Uranus, Neptune and Pluto!
And the link above is only the first "cycle". There's more and more, and yet more will come.
https://jwst.nasa.gov/content/forScientists/faqScientists.html
10. Can Webb observe objects in our Solar System?
Yes. Webb is designed to be able to observe solar system objects having an apparent angular rate of motion of 0.030 arc seconds per second or less. This rate capability includes Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, their satellites, and comets, asteroids and minor planets at or beyond the orbit of Mars. Webb has the near-IR and mid-IR sensitivity to be able to observe and study virtually all known Kuiper Belt Objects. The very large infrared brightnesses of Mars, Jupiter, and Saturn may limit Webb observations of these planets to a subset of the instrument modes.
This blog post from NASA on July 14th summarizes some of the details included in the other answers, and also has early images of Jupiter made during the commissioning period:
The blog post mentions:
Scientists will use Webb to explore the tantalizing question of whether we can see plumes of material spewing out of moons like Europa and Saturn’s moon Enceladus. Webb may be able to see the signatures of plumes depositing material on the surface on Europa.
The accompanying Facebook post notes:
These images are designed for engineering purposes, so they aren’t processed in the same way as our first images this week. Like some earlier calibration images you may have seen, these are processed to emphasize certain features.
So the confirmed answer is yes, it will be able to image objects in the solar system. They will be able to focus on various features because of the improved resolution and different spectra of its imagers compared to Hubble.
Addendum: see also this post of images of Jupiter's auroras.
“Can James Webb take pictures of our solar system? ”
By definition, it must. Or some head will roll.
In order to cover JWST budget overruns, funding was diverted from the Outer Solar System line. JW is now considered to be an “outer planets mission,” by virtue of remote sensing observations. This implies a probe- close-range observations or literal in situ data- have been pushed back to some later date, with later monies. JW is now obligated to do gas-giant cloud morphology and tracking, satellites and rings, etc. or the Outer Planets Group will cry foul.
Closer in, the asteroid/comet cutoff is set by the observatory’s ability to pan itself, for moving objects. The outer planets, Kuiper Belt Objects, comets at long range, etc. are quite stately in their motion. As you get closer to the Sun, things get snappy, per Kepler’s Law. This includes JW itself, so both target and platform could result in a high relative speed and high angular velocity. As baselined, objects much closer than Mars would be moving too fast, and smeared.
As launched, the tracking and attitude systems appear to be performing at or better than nominal. The program is testing the tracking and panning capability, to possibly bring the observing limit inward somewhat.
And of course, scientists might get creative. Hubble and other space observatories took out-of-focus/smeared images when called upon, usually for calibration but sometimes not. Comet investigators, for one, are accustomed to not getting crisp images. And dust will never be resolved- not physically possible. JW observes in infrared, and I’d bet the dust researchers are eager to get time on it.
