The Science of the James Webb Telescope Explained!

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**Matt O'Dowd** (1:00)
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You've probably heard about the James Webb Space Telescope, maybe seen some cool pictures. But why should astronomers have all the fun? How do we get to use this cool new toy ourselves?
The James Webb Space Telescope has now been in full operational science mode for several weeks, and has seen some pretty amazing stuff, from colliding galaxies to planets and exoplanet atmospheres, to the earliest most distant galaxies ever observed. You can check out its amazing accomplishments in lots of places, like the official NASA and Goddard Flight Center websites, and all over YouTube. But special shout out to Anton Petrov for the best, best of JWST I've seen.
Many of you asked whether we were going to do a JWST episode, and at first I thought it wasn't needed due to the massive coverage. But then I realized there's something missing. Rather than tell you about what the telescope has done or will do, I want to talk about the process of actually using a telescope like this. What does it take to get time on JWST, and how can you use it yourself? The fact is, anyone can use JWST. It was built by NASA with significant contributions from the Canadian and European space agencies but it was built for everyone. You don't have to be employed by NASA or a US citizen or even a professional astronomer. But before we get to using JWST, let's talk about the telescope itself. After all, if you're going to use it, you better know what it's useful for. The James Webb Space Telescope. JWST, or the Webb, has been in the works for decades. Really, from right after the launch of the Hubble Space Telescope in 1990 The planning picked up over the 90s, and pretty quickly the core properties of this telescope started to crystallize for what was then the Next Generation Space Telescope, NGST. It was to be a much bigger scope than Hubble because with telescopes size matters. The size of the aperture determines how sensitive it is to very faint objects. Hubble has a 2.4 meter diameter mirror. The NGST had to be much bigger. 8 meters diameter to make it a worthy upgrade, which would give it 6 times the collecting area of Hubble. To get an 8 meter mirror into space under the incredible stresses of space launch, it was realized early on that a foldable mirror was the way to go.
Another early decision that persisted was the focus on the infrared, and I'll come back to why. The history of the development of this telescope is a rocky one. The mission encountered many setbacks, from technological to the fiscal to the political. Its costs grew to consume 25% of NASA's entire budget before being axed by the US Congress, then reinstated, then streamlined, and finally launched, just a decade or so after the original launch goal. The NGST became the James Webb Space Telescope named after the administrator of NASA during most of the 60s.
A controversial choice all on its own that I encourage you to look into yourself. After decades of planning and billions of dollars spent, everyone was relieved to say the least that the telescope deployment proceeded perfectly. JWST now sits at Earth's second Lagrange point, its mirrors fully unfolded and its infrared instruments humming along nicely. JWST wasn't planned just to be a bigger, better Hubble. In fact, it's not that at all. The telescope is focused on the infrared, that light on the longer wavelength side of visible light. Hubble, on the other hand, did visible light into ultraviolet. The choice of long wavelength light specializes JWST for a number of particular signs.