It’s the third anniversary of the launching of the James Webb Space Telescope (JWST, or “Juiced” – well, probably not that last one,) and in that scant amount of time, the telescope has been making hay with the amount of useful data that it’s been downloading to us, even after being shot by an micrmeteoroid. Plus it’s produced some images that kick ass for purely aesthetic reasons.
JWST is an infra-red telescope, capturing portions of the spectrum not visible through normal optical telescopes and not visible to our eyes, and this allows it to photograph details that haven’t been found before. In the image above of Jupiter, the different colors from the surface indicate to some extent the different temperatures of the banding and markings in the clouds, as well as showing the auroras on the poles (that Jupiter has been experiencing right alongside Earth,) and even revealing the very faint ring system that the gas giant has. The bright spot to the left is moon Almathea, while the little speck at the tip of the ring is Adrastea. Click on the image for the full-resolution version, because it’s spectacular.
There’s a lot more to it than that, though. Infra-red penetrates much of the dust that scatters visible light, so we can ‘see through’ many of the cloudy regions in nebulae, finding the stars forming within or even well behind. This also allows it to see into the older portions of the universe, the light from early stars that has been cooling for billions of years. JWST’s resolution is much higher than any single telescope* so far produced, so it’s been finding smaller details than ever before, which includes exoplanets and details within other galaxies, and it’s even been interpreting the spectra of exoplanets to reveal which chemicals and compounds can be found in their atmospheres. In part, this is due to the size of the primary mirrors, stretching 6.5 meters in diameter, giving them six times the surface area of the Hubble Space Telescope (which results in roughly a hundred times the resolving power.) Of course it’s newer too, utilizing the advancements in digital imaging that have taken place in the intervening years. Yet it also sits well outside of any atmosphere, unlike Hubble, which is in orbit around Earth and thus has some small residual effect from the thinning air; Hubble also suffers drag from the same and needs periodic corrections. JWST sits way out there in L2, a Lagrange point of gravitational stability, maintaining a position directly opposite the sun from the Earth, and the combined gravitational pulls from the sun, Earth, and moon all balance it on the head of an imaginary pin, so it needs few corrections. However, it orbits this point, in a large enough circle to just avoid both the Earth’s and the moon’s shadows, which keep its temperature from fluctuating while also permitting constant solar power from the sun – yet the image sensors need to be quite cold to pick up the wavelengths that it’s designed for, so it has a huge five-layer sunshield as well.
Webb has something in the astronomy news virtually every week, so check it out. and wish it a happy birthday, though you’ll have to blow out the candles for it yourself, since it’s too far and not allowed to be that close to a heat source anyway.
* The qualifier in there was single telescope, since there’s a technique called interferometry where multiple telescopes some distance apart from each other can coordinate their images to produce very high resolution; since these are so-far ground based, this also allows them to average out the effects of atmospheric distortion, though it still doesn’t counteract the filtering effects of the atmosphere. However, there are plans for a space-based interferometer telescope using multiple craft similar to JWST, and when this is operational, it’s going to bury Webb’s results.