Because the James Webb Space Telescope is optimized for infrared observations, will this mean that it will not generally be used for, or even capable of, the kind of spectacular pictures the public associates with Hubble?

The HST has returned some truly amazing pictures, including those of stellar nurseries and myriads of galaxies in a deep-field scan. Will the JWST be capable of processing similar pictures -- will the infrared images it collects contain enough information to generate them?

Thanks for your replies.

My guess is it will be spectacular. The success of the Spitzer telescope may serve as an example as it is deeper in IR, too.

The JWST will be capable of seeing objects 2 to 5 magnitudes fainter than the Hubble. I am not sure of the resolution but I would guess it might be slightly better than Hubble due to its mirror diameter 2.5x that of Hubble. Of course, in general, the longer the wavelength, the lower the resolution for a given mirror size.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Thank you for the reply. Yes, it would seem that Spitzer's results would be instructive.

Further, it is my hope that the JWST survives, intact and without diminution, its various current financial challenges.

The infrawebb

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After the recent renegotiations, it's supposed to be in good shape for a 2013 launch. (I work on JWST, in a very small capacity.)

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I'm glad to read good news about the JWST, ToSeek. I do hope to see a successful launch in 2013!

That's a very good and perceptive question. NASA's JWST web site says it will have about 1/2 the angular resolution of Hubble -- IOW, 0.1 arc seconds.

http://www.jwst.nasa.gov/FastFacts.htm

I'm sure JWST will do great things, but from a resolution standpoint, it will apparently be inferior to Hubble, and that assumes JWST isn't downsized during cost cutting.

The good news is ground-based visible spectrum imaging optical interferometry is making progress. Fairly soon ground-based telescopes may exceed Hubble's resolution, at least for some objects.

So even in the awful case of a JWST launch failure, ground-based telescopes will likely handle the visible spectrum fairly well. JWST will be supreme for near infrared, however.

That's an unfair comparison. JWST's best resolution is inferior to Hubble's best resolution because JWST is optimized for longer-wavelength infrared light while Hubble is optimized for visible light, and resolution is correlated with wavelength (the longer the wavelength, the less the resolution). JWST in fact has about three times the resolution of Hubble at infrared wavelengths.

And, as I said above, JWST has been replanned and rescoped for a 2013 launch within the current budget. There's no expectation of any further downsizing, and what downsizing has been done is minimal and doesn't affect the primary science goals.

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All in all, it sounds like JWST will be a most capable instrument, and a worthy successor to Hubble.

By that reasoning the 0.85 meter Spitzer Space Telescope has far more resolution at 160 microns deep infrared than Hubble, since Hubble can't image that at all.

The poster asked whether JWST will be "capable of, the kind of spectacular pictures the public associates with Hubble?"

If he means spectacular to the same resolution in the same visual spectrum, the answer is obviously no.

If he means in the near IR, the answer is yes.

If he means just visually spectacular to the average public who isn't familiar with resolution, probably yes. JWST will likely see things Hubble cannot, due to the IR capability.

However the public will also likely compare JWST images to Hubble for certain objects familiar to them e.g, Mars, Jupiter, Saturn, etc. It will be interesting to see how JWST compares from a public perception standpoint.

Okay, I just bristled because you seemed to be making it sound as if JWST were an inferior instrument to Hubble. You obviously understand that it isn't, just that there's a risk of the public seeing it that way.

I doubt that JWST will be taking many photographs of planets in our solar system (other star systems, definitely) as that wouldn't support its scientific goals. If it does, then it will do so primarily for the sake of public-impressing imagery, which, as you say, might run the risk of seeming inferior to Hubble.

A "marquee" JWST image is more likely to be along the lines of this simulated deep field image.

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Everything I need to know I learned through Googling.

Can you explain why Hubble images look so much nicer than Spitzer
images? The Spitzer images always look blotchy and brown-colored
in comparison. I doubt that it is simply a result of different
resolutions caused by the different wavelength bands, because
most of the images I look at have been reduced in size to fit my
computer screen, which should tend to eliminate differences due
only to resolution.

Speculating wildly, I'd guess that it could be a result of choices
of visible colors used to represent infrared, or perhaps the shape
of the spectral curves of the infrared viewed and/or the visible
light used to represent it. Maybe the Hubble bands are broad and
overlapping, while Spitzer bands are narrow and non-overlapping,
and that somehow makes a difference in the appearance.

-- Jeff, in Minneapolis

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"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

The problem is JWST is almost universally described as "the successor to Hubble". IOW just like Hubble but bigger and better. NASA's JWST page specifically says "JWST...will take the place of the Hubble Space Telescope".

JWST will do great things but it's not exactly a bigger Hubble -- it's optimized for a different spectrum. It's far more capable in the near IR, but actually has less resolution in the visual spectrum. But I don't think that's widely understood by the public at large.

The Hubble Deep Field was amazing but aside from that, probably the biggest public impact was high resolution visual spectrum images of fairly close, bright nebula like the gaseous pillars in M16: http://www.seds.org/hst/M16Full.html, and Eta Carinae: http://www.seds.org/hst/96-23a.html

This in no way diminishes the likelihood of what JWST will accomplish, but if the public is expecting the "successor to Hubble" to further improve on these, I'm not sure that will happen.

Hopefully JWST will show entirely different classes of objects that are equally impressive.

One reason could be much lower resolution. Spitzer's mirror is about 35% of Hubble's diameter, plus you loose resolution from the lower IR wavelength. Spitzer can go down to deep IR, 160-180 microns.

At 160 microns, Spitzer's angular resolution is:

a = 250000 x W / d, where
a = angular resolution in arc seconds
W = wavelength in meters
d = telescope diameter in meters

Or 250000 * 160,000E6 nanometers / 0.85
a = 47 arc seconds

By contrast, at 500 nm visible spectrum, Hubble's is 0.05 arc seconds
On a 50 x 50 arc second object, Spitzer would show 1 pixel, whereas Hubble would show 2500 pixels.

Of course Spitzer can see many things Hubble is blind to.

There could also be a difference in the classes of objects each telescope prioritizes. Hubble has taken many pictures of closer, brighter planetary nebulae which are visually very impressive.

It may take its place, but we all know it will not out perform the Hubble in the visible, or shorter wavelength, spectrum. That is why most want to save the Hubble.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

I do not believe that there will be anything to replace the Hubble the hearts of its many admirers, including this writer. It was -- it is -- the first of its kind.

However, I do not doubt that the JWST will bring its own strengths to astronomy. And there will be other, spectacular images to look forward to.