On Different Wavelengths: Cosmic Graphics

The other day, just as we were leafing through this season's Taschen catalog, wonderful new images of Saturn from the Cassini probe popped up on MSN news. In the catalog, between two volumes devoted to butts and breasts respectively, is the Taschen edition of the Harmonia Macrocosmica by Andreas Cellarius, a colorful atlas of the heavens from 1660, with richly colored engraved plates.

I was struck by the congruence: NASA and JPL are putting together a lush atlas of the heavens too, and since the images are largely “false color”—that is infrared images converted to color ones—they are indulging in the same sort of tinting visible in the Harmonia.

In September, the Cassini probe snapped a new set of wonderful images of Saturn with the sun behind it. The images are as colorful as those in the Taschen book. But does space “really” look like that?

Space, after all, is dark, and to make neat images, one has to meld different parts of the spectrum—visible and invisible—alike. JPL's web page explains that, “this marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006. The full mosaic consists of three rows of nine wide-angle camera footprints; only a portion of the full mosaic is shown here. Color in the view was created by digitally compositing ultraviolet, infrared and clear filter images and was then adjusted to resemble natural color.”

“With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare,” NASA explains, “the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.”

NASA has to sell space to stay in business, and we are basically sympathetic to their plight. I've long been a sucker for the colorful Saturn images JPL's probes have been sending us. The Voyager images, in their bright blues and reds, are now iconic.

The Mars orbiter and the recent journey of the Sojourner robot to a nearby crater has produced a new set of images of the red planet as well. See “Mars as Art”, another JPL production.

NASA and JPL are in the graphics business too. They don't try or pretend to offer “real” views, but manipulated graphics. “The Cassini spacecraft's visual and infrared mapping spectrometer sees light in wavelengths far beyond what the human eye can see. It captures an astonishing 352 wavelengths, ranging from the visible to the infrared.”

Coloring the images on each wavelength provides something like the multiple plates of a print maker.

The results are iconic images that are not “real.” Saturn is the special beneficiary of this sort of treatment, thanks to its rings. Who cannot love the colors in the Voyager probe images, from 1980. Yes, school children should be informed that the planet is not really lush blue and red. At the same time, they might learn something about the spectrum and the spectrometer, about infrared and ultraviolet, about radio telescopes and optical telescopes.

The Harmonia's colors look unreal to us in 2006. But the book represents state-of-the-art printing and engraving for its era. It offers its own view of the cosmos—actually, two or three views of the universe. It presents the Ptolemaic or earth-centered view of the universe, but also, less extensively, the Copernican alternative. In this atlas of the stars, astrology and astronomy are still the same thing.

The constellations are rendered as figures of elaborate detail and rich modeling: not just patterns of stars but vital characters, fully fleshed archers and water bearers. The pages are hand colored in tones of pink and pumpkin, cream and spinach. The rings of orbits are depicted like giant roller coasters in the sky.

Both the Harmonia and the NASA visions of the cosmos remind us that our views of the universe are models and the models are constantly evolving. The recent debate over Pluto's status as a planet reminds us this is true even at the level of the elementary school models of the solar system, rendered in ping-pong balls and BBs.

The cosmic geometry of Saturn, the backlit, ringed planet, is hard not to admire. NASA's images of Saturn make you forget the outer planets are dark and unfriendly places compounded of hostile compounds: gigantic frozen balls of ammonia and methane. Their moons get attention because they might be less forbidding; we might one day land there.

We are jaded now to images of Earth from orbit, and the frustrations of the shuttle and space station. But to anyone who takes time to look, those views are constantly revealing and inspiring.

The first NASA images of the moon and planets were often and rightly compared to the first photographic surveys of the American West by expeditions of the William Powell and others. They demonstrated a wonder for nature, but also a pride of ownership. So do today's images of the solar system, in a different way. They may not ring with the music of the spheres but they do say, hey, look around the neighborhood.