I know this is old news by internet standards at this point but I'm still absolutely ~jazzed~ about the James Webb Space Telescope and the pictures it captured, which were released by NASA over the summer. Being a molecular biologist, while I can appreciate how absolutely COOL looking all the pictures were- I immediately had so many questions about the what and the why surrounding all things JWST. So I thought I would do a little searching and summarize some of my findings here- for anyone else who is just really curious about space but with no technical astrophysics or aerospace engineering training :)
So let's dive right in!
Why are all the mirrors hexagons on the JWST?
I don't know why but this was the very first thing I wondered when I first saw a picture of this gigantic machine:
Turns out, the mirrors are hexagonal so that they can fit into a cylindrical rocket to get launched into space, AND so that when they line up together they form a perfectly flat plane to look out into the universe. Plus- this group of hexagons fits together to make a nearly circular shape, which allows the telescope to pick up on light in a way that makes the images in the detectors as true to their actual dimensions as they can be. A NASA statement about the mirrors reads: "a roughly circular overall mirror shape is desired because that focuses the light into the most compact region on the detectors. [An] oval mirror, for example, would give images that are elongated in one direction. A square mirror would send a lot of the light out of the central region."
What's all this about a telescope being able to see into the past?
Light takes time to travel to our eyes- and similarly, infrared and mid-infrared light take time to travel to telescopes! So while the telescope is not actually time-traveling, it is picking up light that has taken so long to reach it that the space it's imaging for us is actually what that part of space looked like in the past- so the farther away an object is, the longer it takes the light to reach us, and the further into the past that image comes from.
It's really trippy if you think about it for too long- but the way I like to look at it is like the lightning and thunder in a thunderstorm. We're all taught in school that you see the lightning first, and then the thunder because light travels faster than sound. But, it's not that the thunder happens after the lightning- that's just the way we perceive it because of the time and space between our eardrums and the storm. Same thing happens with telescopes and super distant space objects.
The coolest part about this is- the farther away something is, the farther in the past we see it. So as we look out further and further from where we are now, the closer we get to seeing the way the universe looked back when it first came to be!
Plus- since the Universe is expanding- up until now, it's been hard to see things that were that far away from us. So we've never had the ability to look at something so far away, and so far in the past, that JWST presents us with!
What is redshift and why is it important?
Maybe you weren't wondering this but I was and the answer was so cool I had to share it! So I was reading about JWST and I kept seeing things about what "redshift" it can see into- so I did a bunch of digging and learned that redshift is exactly what it sounds like: it refers to light being shifted to appear more red than it is. This sounds pretty boring at first glance, but if you think about it (and look at some diagrams I'll drop below), light that is shifted towards the red end of the spectrum has been stretched out (red light has a longer wavelength than the other colors!). So if something is redshifted- or appears more red than it is- that means that object is moving away from us!
This observation- termed "cosmological redshift" is what indicated to scientists that the universe is expanding, because everything is redshifted! And the farther you go, the higher the redshift.
And actually- this redshift is part of the reason telescopes pick up on infrared light! Objects that are very far away are so redshifted that they go into the infrared realm of light. Without the ability to detect all different types of infrared light, telescopes wouldn't be able to recognize objects super far away from the Earth.
What has JWST been up to since the initial release of images?
Lots!! There have been lots of new pictures released since the original set over the summer, so I'm including a few of my favorites here for your viewing pleasure.
For starters, it took some pictures of Mars!
Scientists were especially excited to see these images of Mars, and perplexed by "Hellas Basin", noted in the image above. Even during the peak of Martian daytime, this part of the planet appeared darker according to infrared imaging, which implies a difference in air pressure. This mysterious spot on Mars is something scientists are continuing to investigate.
JWST also captured some images of Jupiter, with it's iconic "Red Spot" appearing white!
In this bottom picture, you can see "auroral hazes" associated with Jupiters North and South poles.
This cute little picture was taken of the "cartwheel galaxy", which is around 500 million lightyears away! And might I add- look at those red hues- now we all know where those come from, look at us go!
It also captured this image of a galaxy nearly 24 million lightyears away! Those colors look like something straight out of a Marvel movie to me, it's hard to believe this is really what our universe looks like (or, looked like!).