On this date 22 years ago, the Hubble Space Telescope was borne into space on Shuttle Discovery, the one that recently did its last flyby over DC (well, okay, it had help) before delivery to the Udvar-Hazy center. The Hubble will be retired soon, and while this is viewed with some disappointment by everyone who has even a faint interest in astronomy, it’s not like anyone can complain. The images alone have been stunning, revealing a universe that is fascinating in its complexity and variety – but this is a little of a mixed blessing, too. I’m not alone in wondering how breathtaking it would be to travel to some of these cosmic locations like the Cats Eye Nebula (NGC 6543) above, diving through its diaphanous bubbles like a stormchaser circling the eye of a hurricane, but let’s face it – we’re virtually guaranteed never to be able to do something of this sort. The distances are just too vast [you are required by law to use the word “vast” when talking about space], the energy and time required far beyond the reach of our human efforts. And we are restricted to one vantage point as well, save for three-dimensional renditions by clever programmers. Yet, we also have to temper this with the knowledge that getting too close to some of these distant neighbors would be, as they say, “bad.” We’re not getting these light shows at this distance because of a laser in a smoky disco.
Yet, being the source of pretty pictures is the superficial way to look at Hubble, like judging someone by their shoes. We have obtained a tremendous amount of information from these optical observations as well, such as refining the measurements that led to the concept of “dark energy.” In a nutshell: after the initial acceleration of all the mass in the universe from a very small point, gravity should have been slowing things down, dragging its metaphorical feet against the coasting bike of space-time (no, I’ll never be asked to write popular science articles.) Instead, the expansion of the universe is accelerating, and something must be feeding energy into this. I could have continued the space-time bike simile by comparing it to going downhill, but that acceleration is caused be gravity and I’m now confusing the hell out of even myself. Let’s let someone else do this (autoplay video at that link – I wish people would stop doing crap like that.)
Hubble has also contributed a lot to our knowledge of planetary formation, as well. The photos that I highlight in this post disproved a prediction by astronomers that planetary discs would typically remain hidden from our view by surrounding dust clouds. Hubble has even imaged a planet itself around another star, something that is remarkably hard to accomplish:
There’s a little bit of trivia that is worth knowing, if you’ll permit me to return to the idea of Hubble as a camera (just try and stop me!) The bare truth is, every camera, every method that we have of producing images from light, fudges things a bit. Film emulsions contain metals that change their nature when exposed to light, forming crystals, and digital sensors generate a difference in electrical charge. But neither of these can determine the difference between wavelengths except in a very broad range, mostly what we call visible light – in other words, they cannot differentiate color. To accomplish this, they must filter light through substances that permit only specific wavelengths; in film, that’s the emulsion base, a colored gel in which the metals are suspended, and in digital, it’s a membrane over top of the digital sensor. It’s no different for the Hubble Space Telescope, which has colored filters that can be interchanged over its own digital sensors. Every color image from Hubble is a composite of several strictly monochrome images sent back to earth, edited to reintroduce the color, and in most cases enhanced to increase the contrasts between them. A typical computer display does not even remotely approach the range of light and color that our eyes can see, so to provide a better idea of the subtle differences within any photographic target of the HST, the images must be altered. It’s no different than any image I produce myself and put here on the site. This article from Sky & Telescope magazine, used with permission by Hubblesite.org, explains it in more detail.
And finally, I refer you back to this post from two years ago, which contains the video made from the Ultra Deep Field photos, simply because it’s one of the coolest animations ever made. Yeah, you might have seen it already – so? Watch it again. It’s a great dose of perspective, in both directions. While it is easy to feel insignificant in comparison to the unfathomable distances involved, there’s the other side of the coin: we figured out how to actually see this. Damn clever little apes, aren’t we?
But then, I guess we would think that…