I love how people compare the 2 images and say "what's the big deal? Nothing new to be seen"
Here's a summary of what's to learn from someone off reddit..https://www.reddit.com/r/space/comments/vwv1et/first_fullcolour_image_of_deep_space_from_the/ifs7b2w/
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
here.
How did they decide what to observe anyway?
As is the case for all NASA telescopes, anyone in the world can apply for JWST time! You just need to write a proposal justifying why
your idea is better than anyone else's, and well enough that a panel of astronomers agrees. In practice, it's really competitive, and about 4.5x more hours were requested than there are literal hours for JWST to observe (actually way better than Hubble which has been closer to 10x- Hubble can only observe on the night half of the Earth's orbit, but JWST has a sun shade so you get almost nonstop observing). The resulting proposals that won out are all a part of "Cycle 1" which begins this week, and you can read all about them
here. (Cycle 1 includes the Early Release Science projects I discussed above.)
As an aside, while I am not personally involved in it (I'm more on the radio astronomy side of things) I'm super excited because my group has JWST time! We are going to observe what is likely to be the first
neutron star merger observed by JWST- I very much hope to be able to look over the shoulder of the guy in charge of the project type thing.
Because we have no idea on when that is going to happen, we basically have the right to request JWST observations if we see a signal called a short gamma-ray burst that tells us one of these events has occurred, and they'll change the schedule to squeeze us in as soon as they can (probably a week or two, with faster turn around in future years). Whenever it happens, I'm sure I'll tell you guys all about it!
Anyway, a toast to JWST- and if anyone who works on it is reading this, we are all so proud of you! I can't wait to see where this new adventure takes us!
Edit: y'all are too kind! But to answer two common questions:
- I refer to these galaxies as "young" despite being 13 billion light years away from us because we see these galaxies as they appeared 13 billion years ago, when the universe was very young. So when we look at the furthest away things in the universe we are actually seeing the youngest galaxies we've ever seen! Space is wild!
- The lensing appears to be centralized because that is the center of mass of the galaxy cluster. Remember, most of the mass is not in those white galaxies, but instead in the dark matter we cannot directly see (but whose effects we can see thanks to this lensing). Space is really wild!
