Just Because I Can
I’m doing what I shouldn’t here: troll baiting. In the version of this post up on Balloon Juice, a relentless troll whinged about the use of false color in rendering astronomical images both interpretable and beautiful. What follows is (a) stuff I wanted to get off my chest and (b) an excuse to post some cool astronomical images. Enjoy:
I love astronomy. I’ve made a couple of films about telescopes, observatories, and the exploration of deep space made possible by the extraordinary instrumentation created over the last couple of decades. Observational astronomy has undergone a true revolution in my lifetime, and we know more about our universe by direct examination now than we did before, say 1950 by an almost incomprehensibly wide margin because of the two great changes rung in by that revolution.
One of those is astronomy’s gain from the tide that lifts all boats — the incredible rise in precision engineering and the science behind it that underpins so much of modern life, from the digitization of experience to the transformation of medical diagnostics to the tying up of the globe into an unprecedentedly swift, safe and reliable transportation network and so on.
The other truly transformative move in 20th century astronomy was (at least largely) specific to the domain of sensing, remote and direct alike: the realization that it is possible — and important — to look up with detectors that can capture signals from anywhere on the electromagnetic spectrum from gamma rays to radio waves — and not just in the realm of the visible that has defined astronomy from Og the caveman to Hubble (and a little beyond).
Nothing new in any of this potted history, but there’s a bit of method to my madness. The exploration of wavelengths longer than what humans can see (infrared-radio) and shorter (ultraviolet-gamma) has led to utterly new views of the universe, and insight into a whole range of physical phenomena that observations within the range of human sight could never yield. For a quick gestalt on that point, take a look at this:
I’m not sure how easy it is to pick up the identifiers to the left of each image — but the image shows us what our galaxy looks like when examined at different points along the electromagnetic spectrum. When we go out on a clear night (preferably at altitude, away from a city), we see something that looks like the third strip from the bottom. Looking at that, we have essentially no idea of what’s going in the sky — all the signal to be seen everywhere else up and down the picture.
Crucially, there’s a ton of science in (or enabled by) these various views. Emissions of light from some object are signals of some physical process happening to produce that electromagnetic emission. If a star or a galactic center or whatever is pumping out a ton of gamma-rays, that tells us a lot about what’s happening to produce so much light at such high energies — and the same applies up and down the spectrum.
But there’s a problem, or rather a feature of the observations that lead us to the insights available only when we have a multi-spectral grasp of our surroundings. We don’t see X-rays. Nor radio waves, nor any light that doesn’t fall within what’s called, for obvious reasons, the optical or visual band of spectrum. To render those images interpretable, to make them available for communication to each other, we need to perform an act of translation. That’s what’s going on above, when you see images labelled “gamma ray” or “radio continuum” with your own eyes, dressed up in lively shades of red and yellow, purple and blue.
To some (and now I’m getting to it) such coloring is a lie, propaganda with which NASA and space scientists in general trick us into paying for the observatories in space and on earth that generate the data behind the fibs. To sane people, it’s what you do to help you think about and understand what it is you’re looking at/for. And if as a field there is a value placed on aesthetically rich translations of the invisible into the seen? Well, it might be because so many astronomers were first moved to make the night sky their home by images like this:
Which is what Saturn looks like in the optical range, as observed by the Voyager II spacecraft. (Personal note: I was hooked on stuff in the night sky from the time I saw Saturn through a large telescope at Oakland, California’s Chabot Observatory. I was about 10. The sight of the rings swinging into view as I sat at the eyepiece has never left me. Public cultural goods are good.) There’s not much science in that picture, except for the deep pleasure it offers, sufficient to move many more than one into a life’s work.
All of which is prelude to one last image. A
commenter troll in this thread spent inordinate amounts of time and blather complaining about the terrible trickery and deceit involved in Hubble Space Telescope imagery, because, after all, the only thing that comes back off that instrument are strings of 1s and 0s that reflect measurements in various bits of the optical and near infrared chunks of the spectra. The colors are “false” — which is to say not what a naked eye would see, if it had the light gathering capacity of a 2.4 meter-mirror and the ability to stare, unblinking for the requisite amounts of time. The naive American public must, it seems, be protected from twin illusions of knowledge and beauty, lest it thus be gulled into funding more such instruments. Or something.
To which, at long last, I say simply, get a life. Or perhaps more in keeping with the tone of this establishment: copulate yourself with vigor — and an oxidized agricultural implement.
To put that into visual terms, let me offer up for your viewing pleasure an utterly falsely rendered picture that is both sublime and filled with the raw material of insight:
This is a picture of the giant star Eta Carinae, and it’s a photoshop: the blue image is from the Hubble Space Telescope, and shows the relatively cool remnants of an eruption in 1840 that blew off about 10 solar masses, leaving between 100 and 150 times the mass of our sun behind. The orange imagery is a false coloration (a lie!) of x-ray data gathered by another NASA orbiting observatory, the Chandra X-Ray telecsope. That shows what happens when fast gouts of material from the explosion smash into surrounding gas and dust, collisions that heat that shroud to upwards of a million degrees, which is what produces the energetic x-ray emissions. The shape of those observations marks the limit of the region in which this desperately unstable star is interacting with its environment.
Eta Carinae attracts a lot of attention because it is a prime candidate to go supernova — and if/when it does, we’ll have almost scarily front row seats for the show. The composite image above isn’t “necessary” for the investigations of its properties. But it does provide a synoptic view of what’s going on right now, and it sure is pretty.
Which is what we know on earth, and, if not all we need to know, than at least a fine goad to get after the rest.
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