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This is one of the most hotly requested topics for this channel.
Even if you didn’t actively request it yourself, you couldn’t have missed the buzz around the James
Webb Space Telescope. It is more powerful than any other space telescope, including Hubble. So big,
it had to be folded up like origami to fit onto the rocket that carried it into space.
So precise and sensitive, it has to be kept at temperatures not much warmer than absolute zero,
to prevent its own internal heat radiation from getting in the way of its sensors.
So expensive, it cost $10 billion dollars to make, and so complicated it took decades to complete.
300 potential failure points stood between it and proper functionality.
But now it is here. And it has an incredible mission: to study planetary systems for evidence
of life, to understand the formation of planets, stars and galaxies, and to peer out across the
universe to objects so far away, the light they gave off has been travelling for almost as long as
the universe is believed to have existed. In other words, the JWST was built to spot the first stars
and galaxies at the very edge of our knowable universe, objects from the beginning of time.
And the first images have started coming in. I’m Alex McColgan, and you’re watching Astrum.
Join with me on a journey as we look over the early photographs coming out of the James Webb
Space Telescope, and see for ourselves the power and precision of this engineering miracle. It’s
already promising to be spectacular. For those who are new to this channel, we’ve already spent some
time watching the JWST as it’s gone from a work in progress to a fully realised piece of hardware.
It was first conceived in the 1990’s, and was originally intended to cost only a billion dollars
and to launch in 2007. However, numerous setbacks and delays plagued the project, pushing it back
again and again. It was only in December 2021 that it finally launched, and it has been spending
the intervening months slowly unpacking itself, powering up its systems, and testing its hardware.
It is a 6,500kg monster, with a sun shield whose 14x21m dimensions are around the size of
a tennis court. Its mirror for capturing light is 6 times larger by area than Hubble’s lens,
which allows it to pick up more photons from further away to create crisp images.
It boasts numerous cameras and scientific instruments, which allow it to see across
the infrared spectrum. This is a feature that is vital to its unique mission.
Due to the expansion of the universe, all of the light from the furthest reaches of space have been
stretched to the point that no matter what they were to start with, they are all at least infrared
light now. So, the only way to see these light sources is with an infrared telescope. On top
of that, infrared is better at punching through dust clouds and other obscuring debris, giving
the James Webb Telescope the incredible ability to see objects that are beyond the sight of Hubble.
I compare this telescope with Hubble a lot, as the James Webb Space Telescope was originally intended
to be Hubble’s successor. However, given their slightly different fields of view – Hubble can
mostly see in visible light spectrums while the James Webb Space Telescope can almost exclusively
see infrared, and can’t see some visible light spectrums at all – it’s more accurate to say
that the two telescopes compliment each other rather than compete. They work together to form
a powerful duo, expanding our understanding of the universe. But that’s not what you’re here for. You
are here to see what James Webb can do. Beginning in our own galaxy, let’s gradually expand our
vision outwards towards the edge of the knowable universe. You are in for some spectacular sights.
The first stop-off on our journey is a place known as the cosmic cliffs.
The Cosmic cliffs, otherwise known as NGC 3324, are a part of the Carina Nebula about 7,600 light
years away from us. These peaks you’re looking at are massive structures around 7 light-years high,
and what you see here is only a portion of the nebula as a whole. The actual nebula is much
larger, and contains a hollowed-out centre, where the stellar winds given off by stars have blasted
all nearby dust away from them. What we’re looking at here is the edge of this hollowed-out bubble.
Scientists are very interested in this region of space for one very simple reason – it helps
answer questions about the formation of stars. Thanks to the stellar winds in this zone,
dust and matter conglomerate together, forming a birthing place for stars.
However, for all our stargazing, there are still many mysteries surrounding this process.
How exactly do they form? What do the different stages look like? It’s difficult to tell.
Part of the difficulty with finding the answers is the dust itself, both vital to the process and
also a massive impediment to seeing it happen. It wraps around the forming stars like a protective
cocoon, stopping scientists from seeing very clearly what is going on at the moments we’d
like to see the most. James Webb fixes that. Not only does this image provide more detail
than Hubble’s image, but thanks to JWST’s onboard Miri, or Mid-Infrared Instrument, we can peel back
the layers of dust and see what lies within. See how much clearer the image is! This will provide
scientists with data on the formation of stars for a long time yet. So much for the birth of stars.
At our next stop, the JWST uncovers more about the end of their lifespan. And for this, let’s look a
little closer to home to NGC 3132, otherwise known as the Southern Ring Nebula. The image on the left
was taken by JWST’s Near Infrared Camera (NIRCam), while the one on the right was taken again by
MIRI. This is a planetary nebula, although technically that term is a bit of a misnomer.
While regular nebulas are birthplaces of stars, a planetary nebula is not a place planets form.
Instead, it was just an unhelpful naming convention used by early astronomers who noted
the round shapes of these nebulas and thought they looked a bit like planets. The name stuck, even
though our interpretation of the name has moved on. Planetary Nebulas like this one are formed
when dust and gas are blasted out from dying stars towards the end of their lifetimes. Knowing the
chemical composition of this dust is useful, as understanding what materials exist in the universe
helps us to understand what later waves of stars might be made out of. So once again James Webb’s
ability to peel back the layers of dust to see what lies within is invaluable. Compare this with
Hubble’s image to get a sense of the increased detail that JWST is able to bring to bear.
From this scientists have learned that the second star within this system still has not actually
exploded, so the formation of its own planetary nebula is likely still to come. We can also get a
better sense of how the gravitational interactions of the two stars stir the nebula, mixing the dust
together in fascinating patterns. Now, let’s look a little farther out, beyond our galaxy.
If we want to see star creation, it makes sense to find a location like this. 161,000 light years
away from us lies the Tarantula Nebula, so named because it evokes the idea of a giant tarantula,
lurking within its silken web. Aside from its obvious, otherworldly beauty, this area is of
particular note to scientists because of its similarity to a period in the universe’s history
known as the “Cosmic Noon”. At that point, which – to our best understanding – took
place about a billion years after the universe began, star creation was at its most prolific.
It is thought that conditions there would have looked something like this. James Webb has
been able to spot stars here that are only just coming into being – a fascinating period of time
to study. Let’s look further out again. As our gaze extends, we lose track of individual stars,
and start seeing things on a galactic scale. Even here there are beautiful dances being played out.
Stephan’s quintet is a formation of 5 galaxies (although one is not really next to the others,
but just looks that way from our perspective), famous for its being featured in the film “It’s
a Wonderful Life”. It is thought that 4 of these galaxies will one day collide. Indeed, two are
already doing so. James Webb allows us to see clearly the brilliantly hot dust being kicked off
as these two central galaxies circle each other. The gravitational forces here are mindbogglingly
intense. The energy profound. It is a dance that is truly only appreciable at scales like this one.
This image was not taken at a single time, but actually is a composition of almost 1000 separate
images that James Webb took and then scientists put together, giving it incredible resolution
for picking out details. Let’s look farther out again… until even James Webb is straining to see,
in an image known as Webb’s First Deep Field. This image is taken from an area so small,
a single grain of sand held out at arm’s length would block it from your view in the night sky.
At this scale, individual stars are almost completely absent – most of what you see here
are not stars, which would be too small to detect on their own, but galaxies. Here you can see the
fish-lens effects being created by gravitational warping, as (relatively) nearer objects bend
light around them, distorting what lies beyond. We can start to see the edges of the universe.
In this image is one of the oldest galaxies we have ever sighted. It is so far away,
the light from when it was born at the beginning of the universe has only just reached us.
Where is it? We are going to need to zoom in. Do you see it? It is admittedly quite small.
By evaluating markers within the light given off by this tiny red galaxy, scientists are able to
identify how far it has redshifted, and thus how long the light from it has been travelling
by comparing it to normal visible light from similar sources. This tiny dot was found to be
13.1 billion light years away. As far as we know, given that the universe is thought to
be 13.7 billion years old, this is one of the earliest galaxies we will ever be able to see.
Now, you might be disappointed by how small it is. However, there is some room for hope. Compare this
image with a similar one taken by Hubble of the same region: Obviously, JWST’s image is crisper
and clearer, giving more detail and showing more objects. But there is one other vital distinction
between these two images. Hubble took its image by staring at this patch of sky for 10 days, slowly
gathering every photon it could from this region of space and compiling them into a single image.
JWST, on the other hand, took only half a day taking its own image.
What this implies is that if JWST was able to take such a detailed image in 1/20th of the time,
imagine how detailed an image it could take if given a comparable amount of time.
In other words, this tiny little dot is likely not the best that the JWST can do.
I hope these images have given you both a sense of the scientific breakthroughs possible with the
JWST, but also just how beautiful the sights in the universe are. Images like these blow me away.
Sadly, we are going to have to be a little patient to see what other discoveries the JWST
might have in store for us. The JWST has only just finished running through its calibrations,
letting its instruments cool off and making sure everything is working perfectly.
There are queues of scientists fighting over who gets to use it to do what over
the next 5 to 10 years of its expected lifespan. Each second is hotly contested.
It will be investigating exoplanets for signs of hospitable atmospheres for life,
unveiling nebula to find the origins of stars, and will help us to understand the difference between
an old galaxy like ours and the young galaxies that formed just after the Big Bang. With a tool
as powerful as the James Webb Space Telescope, who knows what else we are about to discover?
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Thanks for watching! Be sure to subscribe for more from James Webb. A big thanks to my patrons
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check the links in the description below. All the best, and see you next time.