Image Comparison of James Webb Space Telescope (JWST) Vs. Hubble Space Telescope

This video compares the images of the same area captured by JWST and Hubble Space Telescope.

Comment By u/Andromeda321 on r/Space giving more info:

Astronomer here! This is SUCH a strange but wonderful day (at the start of a strange and wonderful week)- I have literally been hearing about JWST for the majority of my life, since I was a teenager first getting interested in astronomy, and to see that we are now truly in the JWST era is mind-boggling! Not gonna lie, I think a cynical part of me thought something would go wrong and we wouldn't get here... and not only seeing the images, but having such immense pride for the humans who made this possible, is just so emotional. :)

To answer a few quick questions I've seen around:

What is the image of?

A galaxy field called SMACS 0723, located 4.6 billion light years away. What's more, because of the orientation of the foreground galaxies we get to see some really zany gravitational lensing of light from galaxies much further away in this field- about 13 billion years, to be precise! So these are all very young galaxies, all formed just a few hundred thousand years after the Big Bang. Incredible! And wow, never seen galaxies like those lensed ones before- very Salvador Dali, if I may say so.

The ones that appear to have white light are the ones creating the lensing 5-ish billion light years away, and the reddish ones are the lensed ones. (At least, I'm pretty sure that's how it works as a general rule of thumb.) Here is Hubble's view of the same field by comparison, courtesy of u/NX1.

Also note, JWST is an infrared telescope (ie, light more red than red) because its first science priority was to detect the earliest galaxies (it's been under development so long exoplanets frankly weren't the huge thing they are now), and by the time the light from the earliest galaxies reaches us, it has been "redshifted" to these wavelengths. So before you couldn't see these lensed galaxies with Hubble, and to see them let alone in such detail is astounding!

Pretty! Is there scientific value to it?

Yes! The thing to realize is even with these very first images, because JWST is able to see in detail no telescope has had before there's a ton of low hanging fruit. In the case of this image, one of the big outstanding questions is a feature called the UV luminosity function, which tells you the star formation rate in those early galaxies. If you literally just count up the number of galaxies you see in those first JWST images, you'll already know more about the star formation rate in the early universe than we do now! Further, when you study the gravitational lensing pattern, you can learn about those foreground galaxies- things like their mass, and how the dark matter is distributed around them. OMG this is gonna be so neat!

I need more JWST images in my life! What's next?

There is a press conference tomorrow at 10:30am! At the press conference there will be several more images revealed, from the Carina Nebula to Stephan's Quintet (links go to the Hubble images to get you psyched). There will also be some data revealed, such as the first exoplanet spectrum taken by JWST- note, exoplanet spectra have been done before scientifically, but the signal to noise of JWST allows this to be done to greater accuracy than before. (No, this is not going to have a signature from life- it's a gas giant exoplanet, and it's safe to say if it had a signature from life Biden would have revealed that today.)

Pretty pictures aside, can I access the actual science data? And when will we see the first JWST pictures?

The JWST archive will be launched with all the commissioning data for these images on Wednesday, July 13 at 11am EDT, with the first Early Release Science programs' data going up on Thursday. Specifically for the latter, there are "early release science" programs which are going to be prioritized over the first three months (list here) where those data are going to be immediately available to the public, so everyone can get a jump start on some of the science. (Also, the next cycle of JWST proposals is in January, so this is going to be really crucial for people applying for that.) My understanding from my colleague is there are many people in the sub-field of early galaxies who literally have a paper draft ready to go and intend to get the preprints out ASAP (like, within hours), just because there will be so much low hanging fruit for that field in those very first images! Like, I'll be shocked if they're not out by the end of the week, and the place to see those first science papers are on the ArXiv (updates at 0:00 UTC).

You can learn more about the JWST archive.