Today is a big day for astronomy and humanity. It is the day of the James Webb Space Telescope (JWST)’s first images going public.
Well actually, there was a little preview of one of these images yesterday made by the US president, but that was a poorly executed political stunt so let’s ignore it. Disapointing to see that the most anticipated photos of astronomy were presented by and to people who probably don’t even know the planets of the solar system.
Anyways, I’ve been waiting for this day ever since JWST’s launch date back in Christmas day, 2021; I feel like an excited kid all over again seeing the first images and waiting for the countdown.
You’re probably familiar with the Hubble telescope. It’s a nearly 30 year old telescope that has taken some of the most incredible photos in human history. We’ve uncovered a lot about the universe and its mechanisms thanks to Hubble. Even if you hardly know anything about astronomy, Hubble is a recognized word by the mainstream. When you think of a space telescope, it is often the telescope that comes to mind.
While not a very accurate statement, JWST is essentially the successor to Hubble. It is far more technologically advanced, powerful, and ambitious than Hubble. JWST is aiming to detect the light from the very first stars and galaxies, ancient and nearly undetectable worlds around 13.5 billion years old. No telescope has successfully seen this far back in time, perhaps until now.
Beyond the technical capabilities of JWST, what I find so exciting about the telescope is that everything big is happening now. By the time I learned to read and encountered astronomy, Hubble was already taking images for over a decade. I was born in a world where the famous deep field was already public for years.
JWST’s first images came out literally today, we are witnessing the absolute bleeding edge of astronomy right now. The time we are living in now will go down in history as the first moments of JWST’s performance, and we are part of the lucky group that get to witness it live.
JWST is expected to operate for a minimum of 10 years before exhausting its fuel supply, and apparently the perfect launch operation has prolonged its mission to nearly 20 years. There is also hope that advancements in unmanned space operations can allow JWST to be serviced, perhaps lengthening its mission even longer.
The images
We’re in the earliest stages of JWST’s observations but the images are already fantastic. There’s no telling what else the telescope will discover throughout its mission, but the hopes and expectations are high. All images can be found on NASA’s page for better resolution.
Now, for some context, JWST does not observe visible light. It sees in the near and mid infrared band, so the colours in these images are falsified. JWST is designed to see infrared light because of two reasons:
- Infrared light travels better through dust and intergalactic space than visible
- The light of the primordial stars and galaxies have redshifted into infrared; they cannot be seen through visible light
These reasons are why JWST isn’t a true successor to Hubble; they compliment each other rather than compete. JWST sees purely in near and mid infrared, Hubble sees in UV, visible, and some near infrared. JWST is more of a true successor to the Spitzer Space Telescope.
The Webb Deep Field
The first, and best, image is the so-called ‘Webb Deep Field’. This image is essentially a light tech demo of JWST’s capabilities but already displays results more impressive than the best Hubble can muster. You can see the difference from when this cluster was photographed by Hubble, the difference in resolution is amazing.
The light sources in this image are from the distance galaxy cluster SMACS 0723, around 4 billion light years away. The hexagonal glare rays are artifacts caused by the telescope itself and are not from the light sources.
The center of the image has a slight bulge illusion; some of the red galaxies look smeared around a circular area. This is caused by gravitational lensing; the SMACS cluster is massive enough that its gravity bends light in significant amounts. The light from more distant galaxies behind the cluster has been bent, giving the stretched look.
One of the most famous images taken by Hubble is the Hubble Ultra Deep Field. This image represents the maximum performance of Hubble; seeing galaxies around 13 billion years old. Light sources older than this are too faint and have been redshifted beyond the near-infrared, so Hubble cannot detect them. The exposure time for this image was nearly 12 days. Webb’s image took just 12 hours; imagine what it could do with 12 days of exposure time.
Water vapour in an exoplanet’s atmosphere
While this isn’t an image of distant stars or galaxies, it is a good representation of JWST’s precision. This is the spectroscopy data for the planet WASP-96 b’s atmosphere, an extra-solar planet nearly a thousand light years away.
Put simply, this is a test to find water vapour in this planet’s atmosphere. If the vapour is present, it will cause certain wavelengths of light to peak or minimize. That’s exactly what we see here. Don’t automatically start thinking that this planet is habitable; it is a hot Jupiter: A Jupiter-type gas giant planet that orbits its star much closer than Mercury does to the sun.
The real point of this graph is demonstrating JWST’s ability to see the light of the most distant galaxies, but also its capabilities when focusing on objects in our galactic neighbourhood, relatively speaking. The fact that we can perform spectroscopy on tiny objects thousands of light years away is completely insane.
The Pale Blue Dot is a photo of Earth taken from a ‘mere’ 6 billion kilometers away, and we are already a barely recognizable dot in it. And the PBD isn’t even the whole image, it’s a tiny piece of a much larger photo. WASP-96 b is nearly 1.5 million times more distant, being able to directly measure the data of water vapour is a scientific miracle.
Planetary nebula NGC 3132
Nebulae have lots of dust and gas that obscure visible light. Hubble took photos of the same nebula, and it looks much more obscured. Infrared light acts like x-rays, it allows us to see through opaque or foggy layers. The main advantage of infrared is that x-rays are only emitted by extremely hot and energetic bodies, while infrared is emitted by just about everything.
Even as someone whose only ties with astronomy is enthusiasm, being able to see images of objects in a completely new light just amazes me. The upcoming decades are going to be a gold mine for the astronomy and astrophysics field.
Looking to the future
I haven’t covered all of JWST’s first round of publications, you can find the rest of them here. This is only the beginning and with over 10 years of observation to come, I’m really excited to see the fascinating data recorded by JWST.
Once again, the fact that this is all happening in real time is one of the best parts. Whatever stunning discoveries JWST makes, we are here to listen and witness it in person. We’re not reading history books that say people decades before us were shocked, we are the ones that will be shocked.
What’s even more exciting is the anticipation of future telescopes. Right now, NASA is planning the successor to the JWST. It will take decades for a new flagship telescope to begin its operation, but there is a good chance that many of us will be alive to witness that as well.
It’s impossible to guess what we will have discovered by then, but the idea of a future telescope that completely dwarfs even JWST is incredible. There are proposals of telescopes with mirrors at least 3-4 times larger than JWST and with even more incredible technological leaps. We are living in a great time for the advent of 21st century astronomy and it’s incredible all of this information is publicly accessible.