The Peoples Telescope

The Hubble Space Telescope has contributed to the identification of exoplanets, the dark energy that permeates the universe, and massive black holes that lurk in nearby galaxies. Probably no other science facility has left its mark in so many homes or done more to advance the general public’s understanding of the structure, age, and size of the universe. Breathtaking photographs of regions of star formation, stunning spiral galaxies, exploding planetary neb­ula, and the most distant galaxies in the visible universe spill out of coffee table books, adorn the walls of children’s bedrooms, and serve as computer screensavers. Why is that? The answer is not simply that the Hubble images pervade popular culture, though of course they do. There are multiple factors that might account for the telescope’s tremendous popularity and an increasing public awareness of, and affection for, the telescope.

While there are telescopes with twenty-five times the light­gathering power on Earth, Hubble remains the premier tool of astronomers due to its exquisite sensitivity, and the ubiquity of the Hubble photographs has been unprecedented. From newspa­pers and magazine covers, to planetarium and museum programs and displays, popular science books, posters, calendars, and post­age stamps, Hubble images pervade popular culture. Moreover, the emergence of the Internet has afforded global access to the telescope’s photos and scientific results. In July 1994, when Comet Shoemaker-Levy 9 slammed into Jupiter with an estimated ex­plosive force of six hundred times humanity’s entire nuclear ar­senal, Hubble offered up-close views of the devastating planetary impacts. Astronomer David Levy, co-discoverer of the comet, re­ported that millions of people around the world watched on televi­sion or via the Internet as the comet’s line of fragments bombarded the massive planet.20

Art historian Elizabeth Kessler offers several less obvious rea­sons why the Hubble Space Telescope is so cherished worldwide. She contends that Hubble’s spectacular images have become “in­terwoven into our larger visual culture” in part because of their very deliberate construction along the lines of sublime art, which often seeks to evoke grandeur, great height and breadth of field, and an overwhelming awe of the power of nature (plate 19). She points out that many of the Hubble images released by the Space Telescope Science Institute (STScI) and the associated Hubble Her­itage Project reflect the aesthetics of nineteenth-century paintings of the American West. “Light streams from above” in the Hubble images as in landscape paintings, explains Kessler,21 despite the fact that there is no up or down in space. Through such fram­ing strategies Hubble’s photos are often configured like landscape paintings or photographs.

Kessler argues that what also endears Hubble to so many is that its photos provide a means for public audiences “to imagine the possibility of seeing such spacescapes with our own eyes.”22 But Kessler is careful to clarify that all published Hubble photos are interpretations, usually composites of multiple images captured at various wavelengths of light. Even if we could travel at many times the speed of light across the galaxy to observe astrophysical ob­jects, because of the rods and cones in the human eye, we would likely be unable to see color in faint light sources. The reason is that the cones in the human eye allow us to see color, but cones need lots of light to do so. The rods require less light, but do not pick up color. That’s why photographs of the Milky Way arced across the night sky often include color that we cannot see with the naked eye.23

Kessler points out that the Hubble Heritage images are exten­sively processed and represent not what the human eye would see, “but a careful series of steps that translate numeric data into pic – ture.”24 Hubble collects data in visible light but also supports a suite of instruments that “see” at wavelengths not visible to the human eye, such as infrared and ultraviolet light that can reveal additional details. In actuality, HST’s electronic detectors see only intensity, which can be represented in grayscale, a range of shades of black and white, or gray. A set of filters made of colored glass, such as red, green and blue, are rotated in front of the detector as images are captured.25 With spectroscopy, different wavelengths of light are dispersed with a grating and linearly arrayed on the detector. Once the data have been collected, color is added in pro­cessing by combining the images using different filters with the appropriate weights to reproduce “true color”26 that can be used to distinguish gases within a nebula or their temperatures, or to distinguish young, hot, newly formed stars from older, cooler stars.