Holy CMB, Batman!

A press release from NRAO announces, “Astronomers Find Enormous Hole in the Universe.” Hmmm. I’ll refrain from commenting on the overzealous word choice (except insofar as I just did) and focus on the image above.

I have to admit that the first thing I thought of when I saw the diagram was a poorly-rendered traffic cone—with a circular base, executed with an acute lack of graphical perspective.

The caption reads: “Illustration of the effect of intervening matter in the cosmos on the cosmic microwave background (CMB). On the right, the CMB is released shortly after the Big Bang, with tiny ripples in temperature due to fluctuations in the early Universe. As this radiation traverses the Universe, filled with a web of galaxies, clusters, superclusters and voids, it experiences slight perturbations. In the direction of the giant newly-discovered void, the WMAP satellite (top left) sees a cold spot, while the VLA (bottom left) sees fewer radio galaxies.”

The viewer (i.e., astronomers with their WMAP satellite and radio telescopes) is off to the left of the image, and it would probably be worth continuing the sides of the traffic cone until they meet—at Earth! Otherwise, it really doesn’t make much sense. Given its opacity and apparent solidity, the traffic cone looks like a structure, and truncating it simply exacerbates the problem.

Plus, the pictures of the two telescopes distract from what’s going on and further confuse things. They hover there by the tip of the cone, as if they belong there. But the radio telescope wasn’t even part of the observation depicted by the diagram: radio observations supplied confirming evidence.

I admit that I don’t have an immedite solution on how to depict the observations better, although the above image could be improved by making the cone appear more transparent, more a part of some continuous medium affecting the observations, and more connected to an observation point to the left of the image. Oh, and more appropriate in its perspective.

Curiously, the image is offered as a 73KB JPEG, a 278KB JPEG, and… a 34.3 MB TIFF! Now, I’m all about lossless compression of images, and I noticed that the giant TIFF had no compression whatsoever. So, just for kicks, I saved it out with LZW compression and it shrunk to 9.1MB. Yeah, disk space is cheap, but c’mon, let’s be sensible.

Cosmic Color Schemes

I was really asleep at the wheel for this one. A Spitzer Space Telescope press release from 18 December describes the detection of light from “the Universe’s First Objects”—a version of the above image appears as today’s Astronomy Picture of the Day (APOD), which is what tipped me off (sorry to say).

Anyway, the image in question shows light “from a period of time when the universe was less than one billion years old, and most likely originated from the universe’s very first groups of objects—either huge stars or voracious black holes.” In the research paper, this light is referred to as “cosmic infrared background (CIB)” radiation, as opposed to the more familiar cosmic microwave background (CMB)” radiation.

Verbiage aside, what I find odd about this image is the choice to color-code intensity as color. A perusal of the aforementioned research article indicates that color information (i.e., the color of the background signal in infrared light) is minimal, but the blobby fluctuations that range from black to purple to pinkish-red to yellowy-white. To my eye, the color range (I hesitate to use the word “spectrum”) seems forced and unnatural—at least as a way of representing intensity—but I dunno. Honestly, however, I admire the choice to show blocked-out regions, which correspond to areas obscured by nearby stars and galaxies—as grey zones. Truth in advertising, as it were.

An associated image related to the press release confuses me even more. For some reason, data from the Cosmic Background Explorer (COBE) is used instead of data from the much more recent Wilkinson Microwave Anisotropy Probe (WMAP). Why? Perhaps becuse WMAP has better resolution…? I can’t say for sure because there are no units presented with the press images, making comparison difficult—i.e., I’d need to go back to the research article and the WMAP and COBE data to compare the two, which is something I haven’t time to do for a blog that is, in fact, not my day job.

So… I have mixed feelings. It’s a complicated concept to introduce to a lay public, but the variety of false color schemes—from COBE to WMAP to the above—muddy the waters. And it’s garish muddying at that.